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31C-015 Smith Athletic Field notice of intent-Synthetic TurfIi ~, '• ~~ ~~~ n I ~- L. _l ~J ~l ~~ rl Ll IJ ~I ~J J L ~ l i~JI r.._~ U ( 1 ( r NOTICE OF INTENT AND ACCOMPANYING STORMWATER MANAGEMENT REPORT SMITH COLLEGE SYNTHETIC TURF ATHLETIC FIELD AND SITE IMPROVEMENTS PROJECT NORTHAMPTON, MASSACHUSETTS 01063 Prepared For: Smith College 126-West Street Northampton, Massachusetts 01063 Submitted By: Gale Associates, Inc. 163.Libbey Parkway Weymouth, Massachusetts 02189-0004 JN 713060 December 2008 G:\ i .1306p\N 0:[\Covea•.dor, ~l ~~~~ ~ ~ ~~ ,~ NOTICE OF INTENT AND ACCOMPANYING STORMWATER MANAGEMENT REPORT SMITH COLLEGE SYNTHETIC TURF ATHLETIC FIELD AND SITE IMPROVEMENTS PROJECT NORTHAMPTON, MASSACHUSETTS 01063 TABLE OF CONTENTS SECTION 1 WPA Form 3 -Notice of Intent • Figure 1- USGS Locus Map • Figure 2 - FEMA Flood Map l Figure 3 -Estimated Habitats of Rare Wildlife and Certified Vernal Pools Map • City of Northampton -Wetlands Application ~~ SECTION II • Project Summary • Wetland Delineation Summary • Wetland Fee Transmittal Form U SECTION III • Abutter Notification Letter • List of Abutters ~l Under Separate Cover } Stormwater Management Report -Smith College Synthetic Turf Athletic Field and L~ Site Improvements Project, dated December 2008. Plans entitled "Notice of Intent, Smith College Synthetic Turf Athletic Field and Site ~-i Improvements Project, Northampton, MA 01063" dated December 5, 2008. II ~J ( ...~ ~1 C,~:\ r 13060\N0:[\Co~~er.doc ~~ -~, ~, ~ ~ Massachusetts Department of Environmental Protec«on Bureau of Resource Protection -Wetlands ~r~ WPA Form 3 -Notice of Intent Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 r ~ ~~ Important: `- When filling out forms on the ~ computer, use only the tab key i__ to move your cursor - do not use the return key ray ~1 `-~ ~~rn `- J Note: Before completing this form consult I_ your local Conservation Commission ~ regarding any 1 municipal bylaw or ordinance. A. General Information ~' ~;~_;:~ 1 k~; rat;, ,[~~:i-~ hrl t -.i_~I-N ~Iir ~Jllrnk ~r Document T~ ~~nsaction Number i Northampton ~ ~ ~~ ~~ ~~ ~~ City/Town 1. Project Location (Note: electronic filers will click on button to locate project site): College Lane, Smith College a. Street Address Latitude and Longitude: 31C f. Assessors Map/Plat Number 2. Applicant: n~na~ l:. LItJ l+OUC d. Latitude e. Longitude 015 Northampton b. CitylTown -72.64 42.32 g. Parcel /Lot Number contact: John Robinson a. First Name b. Last Name Smith College -Campus Facilities Management c. Organization 126 West Street d. Street Address Northampton MA 01063 e. Cityrl'own f. State g. Zip Code. (413) 585-2406 (413) 585-5696 jrobins2@smith.edu h. Phone Number i. Fax Number j. Email Address 3. Property owner (required if different from applicant): ^ Check if more than one owner a. First Name b. Last Name I c. Organization J ~ll ~_J d. Street Address e. City/Town h. Phone Number 4. Representative (if any): f. State i. Fax Number j. Email address g. Zip Code Paul Tyrell, PE a. First Name b. Last Name Gale Associates, Inc. c. Company 163 Libbey Parkway, P.O. Box 890189 d. Street Address Weymouth MA 02189-0004 e. City/Town f. State g. Zip Code 781-335-6465 781-335-6467 gm@gainc.com h. Phone Number i. Fax Number j. Email address 5. Total WPA Fee Paid (from NOI Wetland Fee Transmittal Form): `--~ $1,575 $775 a. Total Fee Paid b. State Fee Paid r_I i1 ~,) wpaform3.doc • rev. 02/21/08 ,~ $800 c. City/Town Fee Paid Page 1 of 8 I~ .~' Massachusetts D~.~artment of Environmental Protec__.,~n ~~ ~'''~~~'~~ ~''''~ °~'«' Bureau of Resource Protection -Wetlands - - - ~•:1a~sDEP File Number l ~~ ~ : WPA Form 3 -Notice of Intent Do~.irncnt Tr~~n. moon Number; Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 Northampton ~_ City/Town l A. General Information (continued) 6. General Project Description: The proposed project is a renovation of an existing natural turf athletic field to include resurfacing of the field with a synthetic turf field, updated athletic field lighting, relocation of an existing tennis court, paving of an existing gravel parking lot and landscaping improvements. 7a. Project Type Checklist: lJ 1. ^ Single Family Home 2. ^ Residential Subdivision - 3. ^ Limited Project Driveway Crossing 4. ^ Commercial/Industrial `- 5. ^ Dock/Pier 6. ^ Utilities (~ 7. ^ Coastal Engineering Structure 8. ^ Agriculture (e.g., cranberries, forestry) 9. ^ Transportation 10: ®Other 7b. Is any portion of the proposed activity eligible to be treated as a limited project subject to 310 CMR 10.24 (coastal) or 310 CMR 10.53 (inland)? 1. ^ Yes ®No If yes, describe which limited project applies to this project: 2. Limited Project Jl 8. Property recorded at the Registry of Deeds for: U Hampshire a. County b. Certificate # (if registered land) I c. Book d. Page Number ~J ~~ J For all projects ~ affecting other ( l Resource Areas, l please attach a narrative explaining how ~ the resource ~ area was ~~ delineated. i.. , i ~~ B. Buffer Zone & Resource Area .Impacts (temporary & permanent) 1. ^ Buffer Zone Only -Check if the project is located only in the Buffer Zone of a Bordering Vegetated Wetland, Inland Bank, or Coastal Resource Area. 2. ® Inland Resource Areas (see 310 CMR 10.54-10.58; if not applicable, go to Section 6.3, Coastal Resource Areas). Check all that apply below. Attach narrative and any supporting documentation describing how the project will meet all performance standards for each of the resource areas altered, including standards requiring consideration of alternative project design or location. Resource Area Size of Proposed Alteration Proposed Replacement (if any a. ^ Bank b. ^ Bordering Vegetated Wetland c. ^ Land Under Waterbodies and Waterways wpaform3.doc • rev. 02/21/08 1. linear feet 1. square feet 1. linear feet 3. cubic yards dredged 2. linear feet 2. square feet 2. linear feet Page 2 of 8 ~ ~~~ ~ Massachusetts D~ _, artment of Environmenfial Protec _.:n i ~~''~'~~ ~ ~'''~s=D~'~ I ii Bureau of Resource Protection -Wetlands r:,,~~s~~pFiler~~~~~,i~~~ WPA Form 3 -Notice of Intent ~ ~ ~: ' ~ Document Tien>a~,Uc~~ N~irnf,.-r ' Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 Northampton City/Town B. Buffer Zone & Resource Area Impacts (temporary & permanent) (cont'd) ,r-I Resource Area Size of Proposed Alteration Proposed Replacement (if any _. d. ^ Bordering Land Subject to Flooding 1. square feet 2. square feet 3. cubic feet of flood storage lost 4. cubic feet replaced I~ ~__ e. ^ Isolated Land Subject to Flooding 1. square feet 2. cubic feet of flood storage lost 3. cubic feet replaced f. ® Riverfront Area Mill River 1. Name of Waterway (if available) 2. Width of Riverfront Area (check one): ^ 25 ft. -Designated Densely, Developed Areas only ^ 100 ft. -New agricultural projects only ® 200 ft. -All other projects I~ ~J J l_~ Online Users: Include your document transaction U number (provided on your receipt page) with all I ~ supplementary ~ information you submit to the ~ -i Department. u () .I 3. Total area of Riverfront Area on the site of the proposed project: 475,8513 square feet a. Proposed alteration of the Riverfront Area: 59,926 s.f. 20,623 s.f. 39,303 s.f. a. total square feet b. square feet within 100 ft. c. square feet between 100 ft. and 200 ft. 5. Has an alternatives analysis been done and is it attached to this NOI? ®Yes ^ No s. Was the lot where the activity is proposed created prior to August 1, 1996? ®Yes ^ No 3. ^ Coastal Resource Areas: (See 310 CMR 10.25-10.35) Check all that apply below. Attach narrative and supporting documentation describing how the project will meet all performance standards for each of the resource areas altered, including standards requiring consideration of alternative project design or location. Resource Area Size of Proposed Alteration Proposed Replacement (if anv) a. ^ Designated Port Areas Indicate size under Land Under the Ocean, below b. ^ Land Under the Ocean c. ^ Barrier Beach d. ^ Coastal Beaches e. ^ Coastal Dunes wpaform3.doc • rev. 02/21/08 1. square feet 2. cubic yards dredged Indicate size under Coastal Beaches and/or Coastal Dunes below 1. square feet 1. square feet 2. cubic yards beach nourishment 2. cubic yards dune nourishment Page 3 of 8 i 1 Massachusetts a:.,..artment of Environmental Prote~-_ :n Bureau of Resource Protection -Wetlands ~,;, , ~,EP F;ie ~~„ ,t;~, - - - '~ : ~` ~ WPA Form 3 -Notice of Intent -- ` Dc;,um~ nt ~ransactron Numt,~r Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 ~ Northampton City/Town (1 B. Buffer Zone & Resource Area Impacts (temporary & permanent) (cont'd) Size of Proposed Alteration Proposed Replacement (if any) i, f. ^ Coastal Banks 1. linearfeet g. ^ Rocky Intertidal Shores 1. square feet h. ^ Salt Marshes 1. square feet 2. sq ft restoration, rehab., creation i. ^ Land Under Salt I J J Ponds 1. square feet l 2. cubic yards dredged _-.1 j. ^ Land Containing Shellfish 1. square feet n Ic. ^ Fish Runs Indicate size under Coastal Banks, inland Bank, Land Under the L) Ocean, and/or inland Land Under Waterbodies and Waterways, above ~~ 1. cubic yards dredged I. ^ Land Subject to Coastal Storm Flowage 1. square feet ~ 4. ^ Restoration/Enhancement If the project is for the purpose of restoring or enhancing a wetland resource area in addition to the square footage that has been entered in. Section B.2.b or B.3.h above, please enter the additional j 1 U amount here. a. square feet of BVW b. square feet of Salt Marsh ~ J C. Other Applicable Standards and Requirements Streamlined Massachusetts Endangered Species Act/VVetlands Protection Act Review 1 U 1. Is any portion of the proposed project located in Estimated Habitat of Rare Wildlife as indicated on the most recent Estimated Habitat Map of State-Listed Rare Wetland Wildlife published by the Natural Heritage and Endangered Species Program (NHESP)? To view habitat maps, see the Massachusetts r L ~ Natural Heritage Atlas or go to http://www.mass.gov/dfwele/dfw/nhesp/nhregmap.htm. a. ® Yes ^ No If yes, include proof of mailing or hand delivery of NOI to: U Natural Heritage and Endangered Species Program Division of Fisheries and Wildlife October 2008 Route 135, North Drive l b. Date of map . Westborough, MA 01581 ~, j If yes, the project is also subject to Massachusetts Endangered Species Act (MESA) review (321 CMR 10.18). To qualify for a streamlined, 30-day, MESA/Wetlands Protection Act review, please complete Section C.1.C, and include requested materials with this Notice of Intent (NOI); OR complete Section C.1.d, if applicable. If MESA supplemental information is not included with the NOI, ~ by completing Section 1 of this form, the NHESP will require a separate MESA filing which may take up to 90 days to review (unless noted exceptions in Section 2 apply, see below). I~ U wpaform3.doc • rev. 02/21/08 Page 4 of 8 ~ ;!~ ~ Massachusetts D~,~artment of Environmental Protec, n ~ ~~,~J~~i~ ~ ~ : r.~.a-~~~~ Bureau of Resource Protection -Wetlands - - - -- --- :~~i~. -DAP F~ ~ :~ur~,rvr ~ ~ WPA Form 3 -Notice of Intent - Document Transaction Numoer:; Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 Northampton City/Town C. Other Applicable Standards and. Requirements (cont'd) 1. c. Submit Supplemental Information for Endangered Species Review 1. ®Percentage/acreage of property to be altered: 6% / 1.38 Acres (redevelopment) (a) within wetland Resource Area percentage/acreage ~" 9%/2.20 Acres (redevelopment) (b) outside Resource Area percentage/acreage 2. ^ Assessor's Map or right-of-way plan of site s. ®Project plans for entire project site, including wetland resource areas grid areas outside of wetlands jurisdiction, showing existing and proposed conditions, existing and proposed -~ tree/vegetation clearing line, and clearly demarcated limits of work ** n (a) ® Project description (including description of impacts outside of wetland resource area & )I buffer zone) (b) ® Photographs representative of the site L (c) ® MESA filing fee (fee information available at: http://www. mass.gov/dfwele/dfw/nhesp/nhenvmesa.htm) Make check payable to "Natural Heritage & Endangered Species Fund" and mail to NHESP at above address Projects altering 70 ormore acres ofland, also submit: j~ (d) ^ Vegetation cover type map of site U l (e) ^ Project plans showing Priority & Estimated Habitat boundaries U d. OR Check One of the Following 1. ^ Project is exempt from MESA review. ~- Attach applicant letter indicating which MESA exemption applies. (See 321 CMR 10.14, ~ ~ http://www.mass.gov/dfwele/dfw/nhesp/nhenvexemptions.htm; the NOI must still be sent to NHESP if the project is within estimated habitat pursuant to 310 CMR 10.37 and 10.59.) 2. ^ Separate MESA review ongoing. LJ a. NHESP Tracking Number b. Date submitted to NHESP s. ^ Separate MESA review completed. U Include copy of NHESP "no Take" determination or valid Conservation & Management Permit with approved plan. -l _1 Some projects not in Estimated Habitat may be located in Priority Habitat, and require NHESP review (see www.nhesp.org regulatory review tab). Priority Habitat includes habitat for state- i l listed plants and strictly upland species not protected by the Wetlands Protection Act. ~J~ ** MESA projects may not be segmented (321 CMR 10.16). The applicant must disclose full development plans even if such plans are not required as part of the Notice of Intent process. r II U wpaform3.doc • rev. 02/21/08 Page 5 of 8 7 Massachusetts ~ artment of Environmental Prote~, ~n Pry ~~a~ ~ ,,~~ wia ~~oi-~- Bureau of Resource Protection -Wetlands n~~,_,,,~Ee,F~ie Nurn~er r.; ~ ~ ' WPA Form 3 -Notice of Intent _ _ ~ ~ ~: Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 °o0ument iransa°`':,° rd;mher - - Northampton r-, City/Town j ` C. Other Applicable Standards and Requirements (cont'd) _ 2. For coastal projects only, is any portion of the proposed project located below the mean high water ~I line or in a fish run? `_ ' a. ® Not applicable -project is in inland resource area only b. ^ Yes ^ No If yes, include proof of mailing or hand delivery of NOI to either: l South Shore - Cohasset to Rhode North Shore -Hull to New Hampshire: Island, and the Cape & Islands: n Division of Marine Fisheries - l J Division of Marine Fisheries - North Shore Office Southeast Marine Fisheries Station Attn: Environmental Reviewer Attn: Environmental Reviewer 30 Emerson Avenue r 838 South Rodney French Blvd. Gloucester, MA 01930 ~_] New Bedford, MA 02744 ~ ~l online Users: Include your document Also if yes, the project may require a Chapter 91 license. For coastal towns in the Northeast Region, please contact MassDEP's Boston Office. For coastal towns in the Southeast Region, please contact MassDEP's Southeast Regional Office. 3. Is any portion of the proposed project within an Area of Critical Environmental Concern (ACEC)? a. ^ Yes ® No If yes, provide name of ACEC (see instructions to WPA Form 3 or MassDEP Website for ACEC locations). Note: electronic filers click on Website. transaction number b. ACEC (provided on 4. Is any portion of the proposed project within an area designated as an Outstanding Resource Water D your receipt (ORW) as designated in the Massachusetts Surface Water Quality Standards, 314 CMR 4.00? page) with all supplementary a. ^ Yes ® NO information you j ~ submit to the 5. Is any portion of the site subject to a Wetlands Restriction Order under the Inland Wetlands U Department. Restriction Act (M.G.L. c. 131, § 40A) or the Coastal Wetlands Restriction Act (M.G.L. c. 130, § 105)? a. ^ Yes ® No M DEP St t M I i b i i f th t S d d U e ass ormwa er anagemen 6. s project su ject to prov s ons o tan ar s? s th a. ® Yes. Attach a copy of the Stormwater Report as required by the Stormwater Management I I Standards per 310 CMR 10.05(6)(k)-(q) and check if: U 1. ^ Applying for Low Impact Development (LID) site design credits (as described in Stormwater Management Handbook Vol. 2, Chapter 3) 1 ` 2. ® A portion of the site constitutes redevelopment 3. ^ Proprietary BMPs are included in the Stormwater Management System. b. ^ No. Check why the project is exempt: 1. ^ Single-family house 2. ^ Emergency road repair ( 3. ^ Small Residential Subdivision (less than or equal to 4single-family houses or less than or I ~ equal to 4 units in multi-family housing project) with no discharge to Critical Areas. u wpaform3.doc • rev. 02/21/08 Page 6 of 8 ~.~ 1 ~! ~) ~~ ' ~~~id~d h~a f1~ssDCP ~ Massachusetts D~,~artment of Environmental Protec__1n ~~~ `! Bureau of Resource Protection -Wetlands ~_; ,~ ~,~_P Fi,e ra;~~,,~ ---- (} ! WPA Form 3 -Notice of Intent ~ocu n ~ ~t Trnns3eti~n Number; ` Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 Northampton City/Town D. Additional Information Applicants must include the following with this Notice of Intent (NOI). See instructions for details. Online Users: Attach the document transaction number (provided on your receipt page) for any of the following information you submit to the Department. 1. ® USGS or other map of the area (along with a narrative description, if necessary) containing sufficient information for the Conservation Commission and the Department to locate the site. (Electronic filers may omit this item.) 2. ® Plans identifying the location of proposed activities (including activities proposed to serve as a Bordering Vegetated Wetland [BVW] replication area or other mitigating measure) relative to the boundaries of each affected resource area. ~_, s. ® Identify the method for BVW and other resource area boundary delineations (MassDEP BVW Field Data Form(s), Determination of Applicability, Order of Resource Area Delineation, etc.), (~ L J and attach documentation of the methodology. a. ® List the titles and dates. for all plans and other materials submitted with this NOI. Smith College Synthetic TurtAthletic Field And Site Improvements Project a. Plan Title Nathan A. Collins & George Mihov Paul J. Tyrell, PE ~l b. Prepared By c. Signed and Stamped by L December 5, 2008 1"=40'-0" d. Final Revision Date e. Scale f. Additional Plan or Document Title g. Date s. ^ If there is more than one property owner, please attach a list of these property owners not listed on this form. a s. ® Attach proof of mailing for Natural Heritage and Endangered Species Program, if needed. ~. ^ Attach .proof of mailing for Massachusetts Division of Marine Fisheries, if needed. (~ u 8. ® Attach NOI Wetland Fee Transmittal Form s. ® Attach Stormwater Report, if needed. E. Fees 1. ^ Fee Exempt: No filing fee shall be assessed for projects of any city, town, county, or district of the Commonwealth, federally recognized Indian tribe housing authority, municipal housing authority, or the Massachusetts Bay Transportation Authority. l~ Applicants must submit the following information (in addition to pages 1 and 2 of the NOI Wetland Fee Transmittal Form) to confirm fee payment: (7 8 2~9 ~v December 5, 2008 2. Municipal Check Number 3. Check date C7Qi 2 3~j~- December 5, 2008 4. State Check Number 5. Check date Gale Associates, Inc. ~U(~u-r 6. Payor name on check: First Name 7. Payor name on check: Last Name wpaform3.doc • rev. 02/21/08 Page 7 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands "WPA Form 3 -- Notice of Intent Massachusetts Wetlands Protection Act M.G.L.. c. 131, §40 F. Signatures. and Submittal Requirements . . Cify/Town [hereby certify underthe penalties of perjury that the foregoing Notice of intent and accompanying plans, documents, and supporting data are true and complete to the best of my knowledge. I understand that the Conservation Commission will place notification of this Notice in a local newspaper at the expense of the applicant in accordance with the wetlands regulations, 310 CMR 10.05(5)(a). I further certify under penalties of perjury that ail abutters were notified of this application, pursuant to the requirements of M.G.L. c. 131, § 40. Notice must be made by Certificate of Mailing or in writing by hand delivery or certified mail (return receipt requested) to all abutters within 100 feet of the property line of the project location. (2~ 3/08 1. Sig a re of Applicant 2. Date 4. bate d 6. Date For Conservation Comm€ssion: Two copies of the completed Notice of Intent (Form 3), including supporting plans and documents, two copies of the NOI Wetland Fee Transmittal Form, and the cityltown fee payment, to the Conservation Commission by certified mail or hand delivery. For MassDEP: One copy of the. completed Notice of Intent (Form 3), including supporting plans and documents, one copy of the NOI Wetland Fee Transmittal Form, and a copy of the state fee payment to the MassQEP Regional Office (see €nstructions) by certified mail or hand delivery. Other: If the applicant has checked the "yes" box in any part of Section C, Item 3, above, refer to that section and the Instructions for additional submittal requirements. The original and copies must be sent simultaneously. Failure by the applicant to send copies in a timely manner may result in dismissal ofi the Notice of Intent. wpaform3.doc • rev. 02!21!08 Page 8 of 8 i~ ~~ ~i 0 ~~ ~, ~J ~l I}I ~~~ ~_ ~I (~ ~ ~^~, Smith College Athletic Fie~~„_ -1 Notice of Intent PROJECT SUMMARY PS 1 Proposed Activities The Smith College Synthetic Turf Athletic Field and Site Improvements Project is a turf replacement and parking lot improvement project to be undertaken to provide the College with a safe and all season playing surface for their lacrosse and field hockey programs and a dedicated and managed parking facility for users of the athletic campus. The project includes the relocation of one (1) existing tennis court, replacement of an existing natural turf athletic field with new multi-purpose rectangular synthetic turf field, ,updating of the existing athletic field lighting and the paving of an existing gravel parking lot. The new tennis court, synthetic turf field, athletic field lighting and the newly paved parking lot will be used by the same user groups as currently occupying the facility. The existing athletic complex to receive the new synthetic turf field, athletic field lighting, parking lot and improvements is bordered by the Mill River to the east, the Paradise Pond formed by the same Mill River to the north, a small residential development of affordable housing, an equestrian area (property of the Smith College) to .the south and the Northampton State Hospital to the west. The site is accessible via West Street (Route 66) via College Lane, which is a private access drive that dead ends at the existing unpaved parking lot. The athletic complex consists of twelve (12) tennis courts, one (1) synthetic running track with a natural turf field within the track, one (1) natural turf softball field, two (2) multipurpose natural turf fields, several out buildings for storage and bathrooms and gravel parking areas. The project goal is to replace one of the natural turf fields with a synthetic turf field and paving the currently unpaved parking lot to coordinate parking, while maintaining the same number of tennis courts that exist on the site. With the renovation to the existing facilities, Smith College will have astate-of-the- ~ art athletic facility to meet their growing needs of the athletic department and ~,~ keeping them on the same playing field as their competitors. PS 2 Wetland Resources Areas On August 19, 2008, a wetland scientist for Gale Associates, Inc. conducted a field inspection at the Smith College athletic facility to locate potential resource areas on the site that would be subject to jurisdiction under the Massachusetts Wetlands Protection Act (WMPA, M.G.L. c. 131, s. 40) and it's regulations (310 CMR 10.00), as ( well as the Town's Wetland Protection Regulations. The areas delineated were 1 located in field by instrument survey. i~l According to the Massachusetts Natural Heritage Atlas (13th Edition), the site lies within and priority habitat of rare species. Based on a previous Environmental Notification Form submitted by the College for the Paradise Pond Dredging project ~-~ in March 2007, we understand that a habitat of 2 endangered species, 2 threatened Gale Associates, Inc. Page 1 ~ /~~ ~ ~, , l ~ Smith College Athletic Fie. - Notice of Intent species, and 6 species of special concern lies downstream of the project site. They are listed as follows: Scientific Name Common Name Status ~ Dragonflies Gomphus abbreviatus Spine-crowned clubtail Endangered L~ Stylurus scudderi Zebra clubtail Threatened I Stylurus spiniceps Arrow clubtail Threatened Gomphus ventricosus Skillet clubtail Special Concern ~~ Neurocordulia yamaskanensis Stygian Shadowdragon Special Concern ~- Ophiogomphus asperses Brook Snaketail Special Concern Mussels l 1 Alasmidonta heterondon Dwarf Wedgemussel Endangered Alasmidonta undulate Triangle Floater Special Concern ~__ Strophitus udulatus Creeper Turtle Glyptemys insculpta Wood Turtle Special Concern 1 Finally, there are no areas within one mile of the site mapped as Areas of Critical (~ Environmental Concern (ACEC), according to the ACEC Program Guide (June 1993, L Executive Office of Environmental Affairs). (~ PS 3 Impacts to Resource Areas from the Proposed Project ~J As part of the proposed renovations, work will occur within the 100-foot buffer zone J of the abutting BVW (Bordering Vegetated Wetlands), and within the inner and outer riparian zones of the Mill River, both jurisdictional under the MWPA. ~~ The 100' buffer zone of the BVW in the east portion of the site will be impacted due ~ to the re-construction of the existing natural turf field.with a multipurpose synthetic turf field and updated athletic field lighting. The re-construction will include (~ stripping the existing top-soil and sub-soil to an approximate depth of 12", installing ~ filter fabric over the compacted subgrade, installing approximately nine (9") inches of dense graded crushed stone, an elastomeric poure-in-place layer, the synthetic turf fabric and approximately one (1") inche of sand and rubber infill. The work will ~J not result in any additional impervious area within the 100' wetland buffer zone of the BVW and/or the riparian zones of the Mill River. In addition, the limits of the -~ field will be no closer to the existing resource areas than currently laid out today. It should be noted the construction of the synthetic turf field and parking lot will result in no direct alteration of the resource areas surrounding the Mill River. '~ PS 4 Alternatives Analysis The College has investigated multiple alternatives for the site during the Master J Planning efforts performed prior to the design of the proposed work shown in this ~~ `- application. It should be noted that the field proposed is not the maximum size i~ Gale Associates, Inc. Page 2 -~ ~ j Smith College Athletic Fie~~ ~ Notice of Intent I ~ allowed for each individual sport and the College has minimized field dimensions to limit the amount of disturbance to the buffer zones of the adjacent resource areas. One alternative that was investigated was the installation of a similar facility in the front parcel of the Smith College athletic field campus. This alternative provided the same footprint of athletic field space, however it eliminated the existing equestrian area, that is a integral part of the Smith College athletic program. Smith investigated optional sites for the equestrian arena, however there was no feasible site within close proximity to the existing stables and the cost to re-construct the stables or transport the horses for practice and events was substantial. Another alternative to the proposed project would be a no-build alternative, '~ however, due to the College's growing athletic programs and desire to stay ~ J competitive with College's within the region, the field has required too much down time for growing and maintaining a safe, natural turf field. With the construction of the new synthetic turf field, the College will be able to maximize the use of there available field space, take use off of some of the existing natural turf fields by eliminating concurrent uses, while saving on maintenance costs, fertilizer applications, water consumption and loss due to down time. ~J ,~-~ -, ,~ ~~ ~~Z Gale Associates, Inc. Page 3 'I ~_, ~) ( ~ Wetland Delineation & River Bank Demarcation Smith College, College Lane Northampton, Massachusetts -~ u J Introduction The following narrative summarizes the findings of a wetland and bank assessment for the Mill River prepared by GALE ASSOCIATE, INC., of the above-referenced site. The Mill River and its associated bank and bordering vegetated wetland are subject to jurisdiction under the Massachusetts Wetlands Protection Act (M.G.L. c. 131, s. 40) and its promulgating regulations (310 CMR 10.OOand the City of Northampton Wetland Ordinance (Chapter 337). Methodology Field inspection was performed associated with the Mill River by downstream of an impoundment existing natural turf athletic fields downstream approximately 500-ft. below normal stage. Bank Description Mill River on September 19, 2008 to indentify the resource .areas Stuart Clark, P.E. Mr. Clark assessed the area directly dam which forms Paradise Pond. This area is adjacent to at Smith College. The flagging continued from the dam At the time of inspection, the river was flowing at or slightly The Mill River is a perennial water stream as shown on the attached USGS Topographic map (Figure 1.0). The Mean Annual High Water (MAHW) is defined in the Act as: 2. Mean Annual High-Water Line of a river is the line that is apparent from visible markings or changes in the character of soils or vegetation due to the prolonged presence of water and that distinguishes between predominantly aquatic and predominantly terrestrial land. Field indicators of bankfull conditions shall be used to determine the mean annual high-water line. Bankfull field indicators include but are not limited to: changes in slope, changes in vegetation, stain lines, top of pointbars, changes in bankmaterials, or bank undercuts. a. In most rivers, the first observable break in slope is coincident with bankfull conditions and the mean annual high-water line. b. In some river reaches, the mean annual high-water line is represented by bankfull field indicators that occur above the first observable brealc in slope, or if no observable break in slope exists, by other bankfull field indicators. These river reaches are characterized by at least two of the following features: low gradient, meanders, oxbows, histosols, a low flow channel, or poorly-defined or nonexistent banks. c. In tidal rivers, the mean annual high-water line is coincident with the mean high water Zine. The MAHW line was delineated on the west side of the Mill River by a series of yellow flags numbering MAHW 1 thru MAHW 10. MAHW Flag #1 is approximately 120ft downstream of the dam. Flag MAHW 10 is located just down stream of a river guage and sampling station. The following photographs illustrate typical flag locations: r, ~_ _. Il a V J ~ r i r r L_~~~e,~p,i 3, '''~' ~ ~ ~'. "' ' \' ~ fi. nq i ~~ P. Y ~ 1 fi. F 1 (' nfd -~~eCi J ~ ~r Jy 4 . ~' ~ A ~ ~ x ss' ~~~ ~'lvr ~ rso2* - i ~ ( ~' ='~ . a.~ <;~.: - ~.~,~~ ~ _ k ~ ~ ~ ~ ~ ~~}~~j. ~ -L.. ~ t : Y •' ~ L 4 F ~*~ ~ ~~~ ~~\~ `fit. ~~~„ » - k. ~c- s ~.~+ (" ~ MAHW #4 -Downstream of the Lamont Footbridge. Indicated by undercut bank and first break in the primary bank slope. Flag hung on double trunk 4" Beech tree MAHW #7 -Downstream of the Lamont Footbridge. Indicated by undercut bank and first break in the primary bank slope. Flag hung on 5" Beech tree eta ~ ~ ~ ` -I~ ,~ '~ ~',. r. ,4 1 ji ~' Y~ ~` ~ S~' _.. F ( J ~k r; \ i ~ I 1 ~ /~ ~ ~ \ ~ , _4 ~ ~ :~C `ice- 5 ~~` ~l F , {a. I ~ I is Ni~~.a ~ ~' ,~ w.yj " ` ~ ' ~ti~~ ~~` . s ~ ~ ~ ' .,. R, SI ,~.. { ~~ _ ` t f ~ ,~r ~ ~ ~ ` ~. D ~1 Y ' ~ ~.~~ ' ,~~ ,y~r,4.~ t~~. l ~ ~ ~-`:. ~C .~5 l . MAHW #9 -Near storm water discharge. Indicated by undercut bank and first break in the primary bank slope. Flag hung on double trunk 10" Red Maple tree ~, ~ ~~ ~_ r Bordering Vegetated Wetland Description ~~ A Bordering Vegetated Wetland (BVW) was identified on the western side of Mill River just down ~~ stream of the Paradise Pond Dam and continued to the Lamont Footbridge. Downstream of the footbridge there were no wetland indicators or hydric soils to support wetland vegetation due to the steep bank. The wetlands were flagged based on direct observation of vegetation and soil conditions. The 1-- BVW line consists of pink flags with the word "WETLAND DELINEATION" embossed in black. Each flag was numbered #1 through #5. (_l Topography downsteream of the dam consists of a gentle primary slope followed by a moderate secondary slope as you work your way from the river to the top of the bank. The secondary slope directly below the dam is vegetated with sumac (Rhus typhina). This area has stone erosion control armor which terminates at the remnants of a stone and masonry wall. Flags #1 through 3 ~- tend to follow this wall at the interface between the primary and secondary slopes (ie. at the wall). Flags #4 and #5 coincide with the MAWH flags 1 & 2 f ~ Wetland vegetation in this area consist of river-bank grape (Vitis riperia), red maple saplings (Acer rubum) and white snakeroot common fox tail (Alopecurus aequalis) Upland vegetation consists of black locust saplings (Robins pseudoacacia) White snakeroot (Ageratina altissma) stinging nettle (Urtica dioca) Soils below the wall consisted on a thin layer of dark fibrous loam which was saturated. The subsoil consisted of sand and gravels deposited from the outwash from the dam. Soils on the uphill side presented more upland characteristics but were difficult to collect due to rock armament. (~ G:\713060\NOI\Wetland Descriptions.doc I ~ 1~ i~ _~ ~~ ~ ( l Massachusetts ~partment of Environmental Protection Bureau of Resource Protection -Wetlands j ~ NOI Wetland Fee Transmittal Form l l Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 J^ ~ A. Applicant Information Important: `- When filling out forms on the 1. AppllCant: computer, use only the tab key contact: John Robinson to move your a. First Name b. Last Name cursor - do not use the return Smith College -Campus Operations and Facilities n key. c. Organization L } 126 West Street raa d. Mailing Address .o Northampton MA 01063 e. City/Town f. State g. Zip Code 'E1u'" (413) 585-2406 (413) 585-5696 jrobins2@smlth.edu h. Phone Number i. Fax Number j. Email Address l 2. Property Owner (if different): (~ U a. First Name b. Last Name c. Organization U d. Mailing Address e. CitylTown f. State g. Zip Code Email Address x Number j i F h Ph N b . . a . one um er 3. Project Location: College Lane, Smith College Northampton a. Street Address b. City/Town ^-_ To calculate B• Fees , I filing fees, refer U to the category fee list and The fee should be calculated usin the followin six-ste rocess and worksheet. Please see 9 g p p examples in the Instructions before filling out worksheet. instructions for filling out WPA Step 11Type of Activity: Describe each type of activity that will occur in wetland resource area and Form 3 (Notice of Intent). buffer zone. J Step 2/Number of Activities: Identify the number of each type of activity. Step 3/Individual Activity Fee: Identify each activity fee from the six project categories listed in the ~~ instructions. Step 4/Subtotal Activity Fee: Multiply the number of activities (identified in Step 2) times the fee per category (identified in Step 3) to reach a subtotal fee amount. Note: If any of these activities are in a n Riverfront Area in addition to another Resource Area or the Buffer Zone, the fee per activity should be IJ multiplied by 1.5 and then added to the subtotal amount. ~J Step 5/Total Project Fee: Determine the total project fee by adding the subtotal amounts from Step 4. Step 6/Fee Payments: To calculate the state share of the fee, divide the total fee in half and subtract $12.50. To calculate the city/town share of the fee, divide the total fee in half and -add $12.50. ~~ Wpaform3.doc • Wetland Fee Transmittal Form • rev. 2121/08 Page 1 of 2 ~~ ~ ~~ Massachusetts ., ~artment of Environmental Prote~~ion Bureau of Resource Protection -Wetlands NOI Wetland Fee Transmittal Form ,~~ ~ ! ! Massachusetts Wetlands Protection Act M.G.L. c. 131, §40 B. Fees (continued) Step 1/Type of Activity Step 2/Number Step Step 4/Subtotal Activity of Activities 3/individual Fee Activity Fee Catogory 3 (a) + 50% for R.A. 1 $1,575 $1,575 ~~ Step 5/Total Project Fee: $1,575 Step 6/Fee Payments: ~ 1 I Total Project Fee: $1,575 a. Total Fee from Step 5 J State share of filing Fee: b 1~2 Total Fee less $12.50 _ j ~ CitylTown share of filling Fee: $800 c. 1/2 Total Fee plus $12.50 `-' C. Submittal Requirements ~] a.) Complete pages 1 and 2 and send with a check or money order for the state share of the fee, payable to I~ the Commonwealth of Massachusetts. Department of Environmental Protection Box 4062 Boston, MA 02211 b.) To the Conservation Commission: Send the Notice of Intent or Abbreviated Notice of Intent; a copy of J this form; and the city/town fee payment. To MassDEP Regional Office (see Instructions): Send a copy of the Notice of Intent or Abbreviated Notice of `~ Intent; a copy of this form; and a copy of the state fee payment. (E-filers of Notices of Intent may submit these electronically.) ~~ ~~ ,..-~ Wpaform3.doc • Wetland Fee Transmittal Form • rev. 2121108 Page 2 of 2 !1 a Jnvotce Number Date •. Voucher Amount_ ` Discounts: - .Previous:Pay Net; Amount - PROJ,•713060 1`2/4/08 •9075284 `300;00 300.00' NATURAL HERITAGE & ENDAN ooi i . Totals 300:Q.0 300:00. i ~, . . Invoice:Number Date. Voucher Amount :` Discounts Previous Pay Net Amount PROJ. 713060 12/4%08. 0075286 775 00. 775'.00 > MASSAGHUSETfS DEPT..QF E Tptfl~S . 775 00 775.Q0 lJ .pp1; 3 ' .." . I ' ~~ Ii ~l . - .' . .. . ... 1~ .. _..... .... .... .. . _ _ ......_ .. i. O :: iJ ~J ~_ l ,. , . . . ~ .- Gale Associates, Inc. ~~~H~~ Weymlouth MA 02189 0 04gox 890189 ~~ P 781.335 6465 F 781.335.6467 'i CMILYBUSINESSFORM5800.392.6018 ADVANTAI 082396 invorce~Number• Date Voucher Amount Discounts Previous Pay Net>Amount PROJ~ 7;13060, 12/4/08 0075.285 800.00 800.00 NORTHHAMP70N CON$ERVAT - . : Totals 800.00 800.00 ~~ :: 2 n ~1 ~_ SECTION III • Abutter Notification Letter • Certified List of Abutters I~ !I II ,~ i ~J cx:~, ~sosc}~Na:i~<;o~~f:t~.d~~; ~ ~~~ NOTIFICATION TO ABUTTERS UNDER THE MASSACHUSETTS WETLANDS PROTECTION ACT In accordance with the second paragraph of Massachusetts General Laws Chapter 131, Section 40, you are hereby notified of the following: A. The name of the Applicant is: Smith College -Campus Operations and Facilities, 126 West Street, Northampton, MA 01063. B. The Applicant has filed a Notice of Intent (NOI) with the Conservation Commission for the municipality of Northampton seeking permission to remove, fill, dredge or alter an Area Subject to Protection Under the Wetlands Protection Act (General .Laws Chapter J 131, Section 40) and the Northampton By-Law. n C. The address/location of the site where the activity is proposed is: College Lane, Smith ~J College, Northampton, MA 01063. n D. Copies of the Notice of Intent may be examined at the Northampton Conservation Office ;~ between the hours of 8:30 A.M. and 5:00 P.M. on Monday through Friday by appointment only. For more information, call (413) 587-1263_ Ir~ l~ E. Copies of the Notice of Intent may be obtained from the Applicant's representative, Gale Associates, Inc., by calling (781) 335-6465 between the hours of 9:00 AM and 4:00 PM j 1 on Monday throu h~y. ~! F. Information regarding the date, time, and place of the public hearing may be obtained j ~ from Gale Associates, Inc. (Applicant's Representativel, (attn: Nathan A. Collins or LJ George Mihov) by calling (781) 335-6465 between the hours of 9:00 AM and 4:00 PM during regular business days. Notice of the public hearing, including its date, time, and place, will be published on line at www.NorthamptonMA~ and in the Daily Hampshire Gazette /Legal Ads Section at least U seven (7) days in advance. U You may also contact the Land Use and Conservation Planner at the Northampton Conservation Commission at: (413) 587-1263 or the Department of Environmental Protection (DEP) Western Regional Office at (413) 784-1100 for more information about this application or the Wetlands Protection Act. j~ G:\713060\NOl\Hbutter Notification.doc LJ ~~\ ' j n I .._. 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DO zc ~ i z c~ D C --I 2 O Z71 ~~ l l n A n C7 C7 C7 n n n O t7 C7 C7 o-f°00000000000 G - ~~~~~~ r- r-~~~ r- r- fl U n t t r r mxvmmrnmmmmmmmm - ~ ~ mmmmmmmmmmm uN ~ o + N C 22 2 2 2 2 2 2222 ~~~DDDDDDDDDDD I m °_~~~~~~~~~rr-~ ~ .O~.D~AAAAAAAAAAA Z --I W Z Z Z Z Z Z Z Z Z Z Z Z Z y0000000000000n 2 2 2 2 2 2 2 2 2 2 2 2 2 D D D D D D D D D D D D D vvvv-ov-ovvvvv~ -~ --I --I -~ -1 -I -i -i -i -i -~ -~ --i 0000000000000 Z Z Z Z Z Z Z Z Z Z Z Z Z ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ DDDDDDDDDDDDDD ~ I ,_ J m N N O O_ O_ O_ O_ O_ O O_ O O O_ O_ O ~ x 0 0 0 0 0 0 0 0 0 0 0 0 0 -+0000 0000 00000 O Q ~ O O O W W W W W W W W W W W ,fD I j ~ ~;,~/ GALE STORMWATER MANAGEMENT REPORT SMITH COLLEGE SYNTHETIC TURF ATHLETIC FIELD AND SITE IMPROVEMENTS PROJECT NORTHAMPTON, MASSACHUSETTS 01063 December 2008 Prepared for: Smith College 126 West Street Northampton, Massachusetts 01063 Prepared by: Gale Associates, Inc. 163 Libbey Parkway Weymouth, MA 02189 Gale JN 713060 j ~ ~~f GCS ; ,.• Prepared by: ~•+ ~' •`~~ • George Mihov, EIT:~ ~ ~; ~ , Reviewed by: `~ a ~ 7YFit~.l. ~ ~ Pau yrell PE ~ ~ cr~~l~ ~ ~ I , ,..~"fin.,;' ~~'~ ; : ~ ~' ~ ~.• , • ;Isj~... • . i STORMWATER MANAGEMENT REPORT ~ SMITH COLLEGE SYNTHETIC TURF ATHLETIC FIELD fJ AND SITE IMPROVEMENTS PROJECT `- NORTHAMPTON, MASSACHUSETTS 01063 ,`_l TABLE OF CONTENTS ___ 1.0 CHECKLIST FOR STORMWATER REPORT 2.0 PROJECT DESCRIPTION 3.0 BACKGROUND DATA 4.0 STORMWATER MANAGEMENT CONCEPT 5.0 COMPLIANCE WITH STORMWATER STANDARDS 4.1 UNTREATED STORMWATER (STANDARD 1) 4.2 POST-DEVELOPMENT PEAK RATES (STANDARD 2) 4.2.1 EXISTING CONDITIONS 4.2.2 PROPOSED CONDITIONS 4.2.3 PEAK RATE SUMMARY 4.3 RECHARGE TO GROUNDWATER (STANDARD 3) 4.4 REMOVAL OF 80% TSS (STANDARD 4) 4.5 LAND USES WITH HIGHER POTENTIAL POLLUTANT LOADS (STANDARD 5) 4.6 CRITICAL AREAS (STANDARD 6) 4.7 REDEVELOPMENT (STANDARD 7) 4.8 EROSION AND SEDIMENTATION CONTROL (STANDARD 8) 4.9 OPERATION AND MAINTENANCE PLANS (STANDARD 9) 4.10 PROHIBITION OF ILLICIT DISCHARGES (STANDARD 10) 4.11 FLOOD PLAIN (310CMR 10.57) ATTACHMENTS ATTACHMENT A: EXISTING CONDITIONS HYDROLOGY ATTACHMENT B: POST DEVELOPMENT HYDROLOGY ATTACHMENT C: SOILS INFORMATION FOR SITE ATTACHMENT D: OPERATIONS AND MAINTENANCE PLAN ___ i L~ ~J 2 G:V 13060\NOI\Stormwater Management Report.doc f L. _ _ _ _ . _ _ _ Massachusetts L', ,~artment of Environmental Prote~:_.on ~ Bureau of Resource Protection -Wetlands Program ~ Checklist for Stormwater Report _~ 1 A. Introduction Important: A Stormwater Report must be submitted with the Notice of Intent permit application to document When filling out compliance with the Stormwater Mana ement Standards. The following checklist is NOT a substitute for " 1 forms on the 9 I computer, use the Stormwater Report (which should provide more substantive and detailed information) but is offered ' ' only the tab key here as a tool to help the applicant organize their Stormwater Management documentation for their to move your Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, cursor-do not the Stormwater Re ort must contain the en Ineerin com utations and supporting information set forth in use the return p 9~ 9 p _J key. Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include: ~ • The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see ""~' page 2) that certifies that the Stormwater Report contains all required submittals.' This Checklist ~ is to be used as the cover for the completed Stormwater Report. __ • Applicant/Project Name • Project Address ~~ Name of Firm and Registered Professional Engineer that prepared the Report J • Long-Term Pollution Prevention Plan required by Standards 4-6 • Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan. required _ by Standard 8 1 Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. z For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 1 of 8 ~~ ~, ; Massachusetts D~_z ~rtment of Environmental Protec.. )n Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide ~) conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. U Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not ~~ applicable (N.A.) and provide the reasons for that determination. A complete checklist must Include the Certiflcatlon set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. J Registered Professional Engineer's Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution (1 Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- lJ term Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined. that they ~~ have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature U .~-`; y PAUL J. N ~~ "~ s TYR~LL. ~ ~ ~1~ CIVIL ~ ~ PIO. %5910 ;U V ~rl l.`I ~~. L `` .. ~ J'~2 ...`„ ~: _ /~ 2 3 ~a r.. ~ / nature and Date Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? ^ New development ® Redevelopment ^ Mix of New Development and Redevelopment 'I I ~, J I stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 2 of 8 I _ _. - I _. !~ Massachusetts Dr ~rtment of Environmental Protec_, n iJ Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report ~~ Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: ® No disturbance to any Wetland Resource Areas ~J ^ Site Design Practices (e.g. clustered development, reduced frontage setbacks) C~ ^ Reduced Impervious Area (Redevelopment Only) ® Minimizing disturbance to existing trees and shrubs ( ^ LID Site Design Credit Requested: L_.~ ^ Credit 1 L ~ ^ Credit 2 ~~ ^ Credit 3 ^ Use of "country drainage" versus curb and gutter conveyance and pipe ^ Bioretention Cells (includes Rain Gardens) ^ Constructed Stormwater Wetlands (includes Gravel Wetlands designs) ^ Treebox Filter ^ Water Quality Swale ^ Grass Channel ^ Green Roof ^ Other (describe): Standard 1: No New Untreated Discharges ® No new untreated discharges ^ Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth ® Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. i u stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 3 of 8 I_.1 I _. i Massachusetts ~ ;artment of Environmental Prote~.. 1n '~I Bureau of Resource Protection -Wetlands Program ~ Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation ^ Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. ^ Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. ® Calculations provided to show that post-development peak discharge rates do not exceed pre- development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24- hourstorm. Standard 3: Recharge ^ Soil Analysis provided. ® Required Recharge Volume calculation provided. ^ Required Recharge volume reduced through use of the LID site Design Credits. ® Sizing the infiltration, BMPs is based on the following method: Check the method used. ^ Static ®Simple Dynamic ^ Dynamic Field' ^ Runoff from all impervious areas at the site discharging to the infiltration BMP. ® Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations . are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. _ ^ Recharge BMPs have been sized to infiltrate the Required Recharge Volume. ® Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: ^ Site is comprised solely of C and D soils and/or bedrock at the land surface ^ M.G.L. c. 21 E sites pursuant to 310 CMR 40.0000 I~ ^ Solid Waste Landfill pursuant to 310 CMR 19.000 I ®Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. [__] ^ Calculations showing that the infiltration BMPs will drain in 72 hours are provided. _ _., ^ Property includes a M.G.L. c. 21 E site or a solid waste landfill and a mounding analysis is included. i~l-=~1 ' 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 4 of 8 __l i, Massachusetts D'~ ~rtment of Environmental Protec _ , Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (contintaed) Standard 3: Recharge (continued) ^ The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. ® Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following: • Good housekeeping practices; • I Provisions for storing materials and waste products inside or under cover; __ _ • Vehicle washing controls; • Requirements for routine inspections and maintenance of stormwater BMPs; ~ Spill prevention and response plans; l t Provisions for maintenance of lawns, gardens, and other landscaped areas; • Requirements for storage and use of fertilizers, herbicides, and pesticides; • C Pet waste management provisions; • J Provisions for operation and management of septic systems; • Provisions for solid waste management; • Snow disposal and plowing plans relative to Wetland Resource Areas; ~~ Winter Road Salt and/or Sand Use and Storage restrictions; • Street sweeping schedules; • Provisions for prevention of illicit discharges to the stormwater management system; j ~ U Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; • Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. J ^ A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. I ^ Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for ._ calculating the water quality volume are included, and discharge: ._ . ^ is within the Zone II or Interim Wellhead Protection Area ^ is near or to other critical areas ^ is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) ^ involves runoff from land uses with higher potential pollutant loads. ^ The Required Water Quality Volume is reduced through use of the LID site Design Credits. ® Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44%TSS removal pretreatment requirement, are provided. ~~_~ stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 5 of 8 ~~ _l j i Massachusetts D~rtment of Environmental Proteo n Bureau of Resource Protection -Wetlands Program ~~;~ Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) ® The BMP is sized (and calculations provided) based on: ~ ®The'/~" or 1" Water Quality Volume or ~ I ®The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. f ~ ^ The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary L-.~ BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying [_l performance of the proprietary BMPs. ^ A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing ~ that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) `- ^ The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution+ ~ Prevention Plan (SWPPP) has been included with the Stormwater Report. ) ^ The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior r to the discharge of stormwater to the post-construction stormwater BMPs. J ^ The NPDES Multi-Sector General Permit does not cover the land use. ^ LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow L LJ melt and runoff, and been included in the long term Pollution Prevention Plan. ^ All exposure has been eliminated. ^ All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. ^ The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas ^ The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. ^ Critical areas and BMPs are identified in the Stormwater Report. ;i J stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 6 of 8 r i ~- Massachusetts [` ;artment of Environmental Prote~ _ ~n Bureau of ResourceProtection -Wetlands Program j ; Checklist for. Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable ® The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: ^ Limited Project ^ Small Residential Projects: 5-9 single family houses or 5-9 units in amulti-family development provided there is no discharge that may potentially affect a critical area. ^ Small Residential Projects: 2-4 single family houses or 2-4 units in amulti-family development with a discharge to a critical area ^ Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff ^ Bike Path and/or Foot Path ® Redevelopment Project ^ Redevelopment portion of mix of new and redevelopment. ^ Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met)`and an explanation of why these standards are not met is contained in the Stormwater Report. ® The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: • Narrative; ~ Construction Period Operation and Maintenance Plan; ~- ~ Names of Persons or Entity Responsible for Plan Compliance; • Construction Period Pollution Prevention Measures; l Erosion and Sedimentation Control Plan Drawings; ~._J Detail drawings and specifications for erosion control BMPs, including sizing calculations; • Vegetation Planning; • Site Development Plan; j' Construction Sequencing Plan; • Sequencing of Erosion and Sedimentation Controls; • Operation and Maintenance of Erosion and Sedimentation Controls; r I Inspection Schedule; L- Maintenance Schedule; • Inspection and Maintenance Log Form. ® A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing ~~~-~ the information set forth above has been included in the Stormwater Report. '~ ~!I 'J stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 7 of 8 ~'~, ~ Massachusetts ~artment of Environmental Prote,~n Bureau of Resource Protection -Wetlands Program ~~~;' Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) ^ The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. ^ The project is not covered by a NPDES Construction General Permit. 1 J ^ The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. ~ ®. The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. -~ The SWPPP will be submitted BEFORE land disturbance begins. Sta ndard 9: Operation and Maintenance Plan l ® The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: D ®Name of the stormwater management system owners; ® Party responsible for operation and maintenance; ~J ®Schedule for implementation of routine and non-routine maintenance tasks; r ® Plan showing the location of all stormwater BMPs maintenance access areas; ~J ^ Description and delineation of public safety features; _ ^ Estimated operation and maintenance budget; and __I ^ Operation and Maintenance Log Form. ~ ^ The responsible party is not the owner of the parcel where the BMP is located and the Stormwater l l Report includes the following submissions: ^ A copy of the legal instrument (deed, homeowner's association, utility trust or other legal entity) ~ that establishes the terms of and legal responsibility for the operation and maintenance of the __ project site stormwater BMPs; _ ^ A plan and easement deed that allows site access for the legal entity to operate and maintain l BMP functions. J Standard 10: Prohibition of Illicit Discharges ^ The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; ® An Illicit Discharge Compliance Statement is attached; J ^ NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. ;_~ '~.I '--~ stormwater checklist • 04/01/08 Stormwater Report Checklist • Page 8 of 8 r - ~~ ~\ ~~ ~ ~ ~ __ __ ~I 2.0 PROJECT DESCRIPTION The Smith College Synthetic Turf Athletic Field and Site Improvements Project is a j turf replacement and site improvements project to be undertaken to provide the - College with a safe and all season playing surface for their lacrosse and field hockey programs. The project includes the relocation of one (1) existing tennis court, replacement of an existing natural turf athletic field with new multi-purpose ~- J rectangular synthetic turf field, updating of the existing athletic field lighting and the paving of an existing gravel parking lot. The new tennis court, synthetic turf field, athletic field lighting and the newly paved parking lot will be used by the same _~ user groups as currently occupying the facility. The existing athletic complex to receive the new synthetic turf field, athletic field lighting, parking lot and improvements is bordered by the Mill River to the east, the Paradise Pond formed by the same Mill River to the north, a small residential development of affordable housing, an equestrian area (property of the Smith College) to the south and the Northampton State Hospital to the west. The site is accessible via West Street (Route 66) via College Lane, which is a private access drive that dead ends at the existing unpaved parking lot. The athletic complex consists of twelve (12) tennis courts, one (1) synthetic running f_,.i track with a natural turf field within the track, one (1) natural turf softball field, two ~_~ (2) multipurpose natural turf fields, several out buildings for storage and bathrooms and gravel parking areas. The project goal is to replace one of the natural turf fields with a synthetic turf field and paving the currently unpaved parking lot to ~!] coordinate parking, while maintaining the same number of tennis courts that exist on the site. Currently, the site stormwater from the existing natural turf field flows overland into a series of catch basins which discharges directly into the Mill River. Runoff generated by the existing unpaved parking lot flows overland into adjacent vegetated areas, which flow directly into the Mill River. None of the existing run-off is treated prior to discharge. The predevelopment model treats' the entire site as one sub area discharging into the Mill River. Water and sewer are available within the existing Field House and Tennis Building facility located within the athletic complex. The design does not include any improvements related to water or sewer services for the buildings. The field is currently irrigation from municipal water, however the portion of the irrigation system servicing the natural turf field to be upgraded into a synthetic turf field will be removed. A portion of the site is within the 500-Year Flood Plain according to the FEMA Map 2501670002A issued April 3, 1978. 3 ~-~ G:V13060\NOI\StormwaferManagemenlReport.doc _. ~, ~r j According to the Massachusetts Natural Heritage Atlas (13-th edition), certified 1 vernal pools are not located on the site or within aone-quarter mile of the site (refer to attachments). According to the Massachusetts Natural Heritage Atlas (13th Edition), the site lies within and priority habitat of rare species. According to the Soil Conservation Service's "Soil Map -Hampshire County, Massachusetts, Central Part ", the soil units mapped on the site are as follows: • Water (1) . • Raynham silt loam (30A) -covers the majority of the land to be redeveloped • Boxford silt loam (220C) • Amostown-Windsor silty substratum-Urban land complex (741A) 1.0 BACKGROUND DATA Property lines and topographical conditions were compiled from instrumental I~ surveys performed by Huntley Associates, Inc. on August 12, 2004 and Gale Associates, Inc. performed in August, 19, 2008. ,I _l Wetland boundaries were flagged by Gale Associates, Inc. and surveyed on August `J 19, 2008. ~~ 2.0 STORMWATER MANAGEMENT CONCEPT The project is designed to comply with the Massachusetts Stormwater Management Guidelines as a redevelopment of existing athletic fields. No direct disturbance of I.1 wetlands is proposed. Some work within the 100' wetland buffer (jurisdictional under the town of Northampton Wetlands Protection regulation 337-2) and the inner and outer riparian zones of the Mill River, will be performed. All of the work ;_, pertains to the redevelopment of existing natural turf field that already encroaches on the resource area buffers. The proposed project has been designed to minimize encroachment on wetland buffer. No alteration is proposed for the existing points of ~_] stormwater discharge and the complex has been designed to decrease peak rates of runoff to the Mill River for the 2, 10, 50 and 100 year storm events. 3.1 Post Development Condition Hydraulic Sub Areas: The site, as analyzed by Gale Associates, is broken down into three (3) hydraulic sub areas: 1 Sub Area 1 is comprised of impervious tennis courts, bituminous concrete parking lot areas and bituminous concrete sidewalk areas, which replace a portion of the existing gravel parking area. ,L ~ -_ 4 G:\713060\NOI1Slormwater Management Report.doc i _ ,.- - - _ _ . _ _.__.. _ . __ .._ _ .__ _ _ _. _ _ ~ _ _ _ _ _ _. _ ... ._ _ _ _ _ _ _ _ ._.. _ . _ I ___ ~~ ~ (j Sub Area 2 is comprised of bituminous concrete parking lot areas and bituminous concrete sidewalk areas, which replace a portion of the existing gravel parking area. Sub Area 3 is comprised of the one (1) proposed synthetic turf field, bituminous concrete sidewalk areas and undisturbed natural grass/landscaping areas. Runoff Collection and Discharge: Sub Area 1: Runoff generated by the proposed tennis court and the portion of the ~ proposed bituminous concrete parking lot in Sub Area 1 will sheet flow into a -~ proposed vegetated detention basin. The runoff accumulated in the vegetated _ detention basin will recharge into the ground water and overflow into a ~ proposed pipe system and finally into Mill River via an existing discharge --~ outlet. It is not expected the runoff from the tennis court to contain any contaminants, since it will be used exclusively for foot traffic and it .is: not ~_~ expected the runoff generated from the proposed bituminous concrete parking lot to contain more contaminants than the runoff generated from the existing parking lot. Sub Area 2: Runoff generated by the portion of the proposed bituminous concrete parking lot in Sub Area 2 will sheet flow into a series of deep sump catch basin furnished with oil separator hoods. The catchbasin will outlet to 12" HDPE pipe which connects to an existing drainage manhole that discharges directly to the Mill River via an existing 24" RCP pipe. It is not expected the runoff generated from the proposed bituminous concrete parking lot to contain more contaminants than the runoff generated from the existing parking lot. Sub Area 3: ~ _~ During a rain event the water falling within the area of the synthetic turf field will flow vertically through one (1") of sand and rubber infill, one (1") inch E-layer, approximately nine (9") inches of crushed gravel stone base. Once at subgrade elevations, stormwater will flow laterally for approximately fifteen (15') feet through the crushed stone along the filter fabric and into a s r l series of flat panel drains. The panel drains will flow across the subgrade u and connect to a series of twelve (12") inch collector pipes that will tie into an existing 15" RCP pipe that discharges directly to into the Mill River. This 1 process of flow through the stone base results in ari extended time of ~ concentration which significantly offsets the peak flow rate of the runoff generated: As a result the stormwater from the storm event has the ~~ ~J 5 G:\7130601N01\stormwater Management Report.doc n ~ ~~~~ opportunity to go through the filter fabric and recharge into the ground water or flow through the drainage system and reach the Mill River directly. 4.0 COMPLIANCE WITH STORMWATER STANDARDS 4.1 Untreated Stormwater (Standard 1) -- ~ The project is designed so that new stormwater conveyances (outfalls/discharges) do not discharge untreated stormwater into, or cause erosion to, wetlands. 4.2 Post-Development Peak Rates (Standard 2) l_ I A hydrologic study was performed to determine the rate of runoff for the 2, 10, 50 and 100-year storm events under pre-development (existing) (~l conditions. Unmitigated post-development rates were then computed: in a l I similar manner. The study point where the peak rates were compared were taken at the outlets to the entire site at Mill River. From these analyses it lJ was determined that the proposed project and its stormwater management l system would not increase the peak runoff rates above existing levels. It is the intent of the stormwater management system to minimize impacts to r ^~ drainage patterns, downstream property, and wetlands while simultaneously U providing water quality treatment to runoff prior to its release from the site or discharge to wetlands. The U.S.D.A. Soil Conservation Service (SCS) Technical Release 55 (TR-55), 1986, was used as the procedure for estimating runoff. A SCS TR-20-based computer program was used for estimating peak discharges. TR-55 is a ~, 1 generally accepted model for use on small sites that begins with a rainfall u amount uniformly imposed on the watershed over a specified time ~ - distribution. Mass rainfall is converted to mass runoff by using a runoff curve ~ 1 number (CN). CN is based on soils, plant cover, impervious areas, interception, and surface storage. Runoff is then transformed into a 1 hydrograph that depends on runoff travel time through segments of the (I watershed. i - Development in a watershed changes its response to precipitation. The most ~_~ common effects are reduced infiltration and decreased travel time, which result in significantly higher peak rates of runoff. The volume of runoff is I~ determined primarily by the amount of precipitation and by infiltration characteristics related to soil type, antecedent rainfall, type of vegetal cover, ~ impervious surfaces, and surface retention. Travel time is determined primarily by slope, flow length, depth of flow, and roughness of flow surfaces. 1 Peak rates of discharge are based on the relationship of the above parameters `-' as well as the total drainage area of the watershed, the location of the ~ ~ development in relation to the total drainage area, and the effect of any flood ,_.~ 6 G: V 130601N01\Stormwater Management Report.doc ' 1_ I_ ~ _.I ~ 1 (~ i i ~ _. control works or other manmade storage. Peak rates of discharge are also ~ influenced by the distribution of rainfall within a given storm event. ~l j Stormwater management computations for the full-build were performed using SCS based Pond Pack for existing and proposed conditions curve numbers, time of concentrations and unit hydrograph computations. 4.2.1. Existing Conditions Table 4.2.1. Shows the curve numbers, areas and times of concentration used to develop the nre-development hvdrolo~ic model of the site. Table 4.2.1. -Existing Conditions Area Surface Cover Curve Number (CN) Area (Acres) Tc (Hours Remarks Sub 1 0.0833 Actual Tc=0.0804 Im ervious 98* 0.15 Court and SW Grass 74* 2.84 Natural Turf Field Compact Soil 89* 0.56 Gavel within ROW Total 3.55 *CN based on Class C soils as de icted from NRCS soil ma . ~__ ~. 4.2.2. Proposed Conditions There will be three main areas of alteration of the ground surface cover in the proposed development; (1) the relocated tennis court; (2) .the proposed synthetic turf field; (3) the proposed parking lot. The relocated tennis court does not generate a net increase of the impervious area. for the site since an existing tennis court will be demolished during construction. The time of concentration for the runoff generated by the synthetic turf surfaces will be increased due to flow through the stone base under the synthetic fields. The result is that the peak flow rate of the runoff generated is significantly offset from the peak flow rate for the rest of the site. The synthetic turf field serves to collect, detain and control the release of the majority of the Stormwater runoff so as to not increase the peak rates of runoff in the full build condition. The project also mitigates the runoff from the impervious surfaces by sending it through a system of catch basins connected by HDPE pipes. ~J 7 ~ --~ G:\713060\N01\Stormwater Management Report.doc j __ 1 '--- ,~ ~,~ ~~ I Table 4.2.2. Shows the curve numbers, areas and times of concentration used to develop the nost-development hvdrolo>Tic model of the site. Ta ble 4.2.2. - Proposed Conditions Area Surface Cover Curve Number (CN) Area (Acres) Tc (Hours) Remarks Sub 1 0.0833 Calculated Tc=0.0251 Im ervious 98* 0.60 Tennis and Parkin Grass ~ 74* 0.04 Sub 2 0.0833 Calculated Tc=0.057 Im ervious 98* 0.26 Parkin and SW Grass 74* 0.007 Sub_3 0.6733 Im ervious 98* 0.08 SW Grass 74* 0.46 S nth. Turf 79* 2.10 S nthetic Field Total 3.55 *CN based on Class C soils as de icted from NRCS soil ma . 4.2.3. Peak Rate Summary Table 4.2.3. Shows the peak runoff and the volume of the runoff for the existing as well as for the developed site at 2, 10, 50 and 100-year design storms. Table 4.2.3. - Stormwater Runoff Volume and Peak Rate Summary Area Design Storm Existing Runoff* (CFS) Existing Volume* (Ac-Ft) Proposed Runoff* (CFS) Proposed Volume* (Ac-Ft) Total 2-yr 3.90 0.32 1.37 0.40 10- r 8.17 0.65 2.31 0.73 50-yr 12.75 1.03 3.27 1.09 100- r 14.00 1.13 3.56 1.19 *Values taken at point of storm water dischar e into Mill River. 4.3. Recharge to Groundwater (Standard 3) There will be three main areas of alteration of the ground surface cover in the proposed development; (1) the tennis court; (2) the paved parking lot; (3) the synthetic turf athletic field. The project mitigates the runoff from the impervious surfaces of the tennis court and a portion of the parking lot by sending it into a vegetated detention basin. While detained in the detention basin the water has the opportunity to recharge into the ground water. 8 G:V 13060\NOI1Stormwater Management Reporl.doc _- _ (, The project mitigates the runoff from the synthetic turf field by sending the storm water vertically through 1" of sand and rubber infill, 9" of crushed gravel stone base, laterally through the crushed stone along the filter fabric, and finally into the flat drains leading to the 12" collector pipe that sends the runoff into an existing drainage manhole and via existing 15" RCP pipe into the Mill River. As a result the water from the storm event has the opportunity to go through the filter fabric and recharge into the ground. 1 Finally, runoff that did not infiltrate before reaching the drainage system or ~~ while running through the perforated HDPE pipes is released into the Mill River in a pattern similar to the pre-development conditions on the site. ~ Loss of annual recharge to groundwater should be mitigated through the use --I of the above described infiltration measures to the maximum extent practicable. The annual recharge from the post-development site should approximate or exceed the annual recharge from the pre-development or -- existing site, based on soil types. Runoff volumes will not increase significantly after construction on this site. Required Recharge Volume for the entire site was calculated in accordance i `l with the Massachusetts Stormwater Management Standards: Rv = F * impervious area Rv = (0.25/12) * 0.94 = 0.0196 Ac-ft = 853 CF Rv =Required Recharge Volume F =Target Depth Factor (0.25 in for soils of Hydrologic Soil Group C) I~ Impervious area =pavement and rooftop area on site (0.94 Ac) Required minimum Surface Area of the bottom of the infiltration structure I.~ was calculated in accordance with the Simple Dynamic Method as outlined in the Massachusetts Stormwater management Standards: A = 854 CF / (0.32 ft + 0.01417 ft/h * 2h) = 2,452 SF ~J A =minimum required surface area of the bottom of the infiltration structure Rv =Required Recharge Volume D =depth of the infiltration facility (only void spaces are considered in stone facilities, so D = nod = 0.35(11/12) = 0.32 ft) K =saturated hydraulic conductivity (0.17 in/h = 0.01417 ft/h conservative value for soils of Hydrologic Soil Group C) ~l T =allowable drawdown during the peak of the storm (2h) 9 ~ I G:V 130601N01\Stormwater Management RepoR.doc '~ _ _ ._ _ _ ~~~~ (~) Area of the proposed synthetic turf field to be used as an infiltration structure is 91,640 SF and is sufficient to assure recharge exceeding the predevelopment levels. 4.4 Removal of TSS (Standard 4) The runoff from the impervious surface of the western portion of the parking lot will sheet flow down mellow paved surfaces until it reaches the vegetated detention basin. While in detention, a substantial part of the TSS will settle and remain in the detention basin. Runoff generated by the eastern portion of the paved parking lot will sheet flow down mellow paved surfaces until it reaches the intended catch basin. The proposed storm water management system design calls for catch basins with sumps to collect runoff from the paved area. ~-~ The proposed athletic field has low potential for accumulation of total _ suspended solids (TSS). Runoff generated by the synthetic turf field'.:. will r travel vertically through 1" of sand and rubber infill, through 9" of crushed gravel stone base, then laterally through the crushed stone along the filter fabric, and into the flat drains leading to the collector pipe. lJ All of those runoff collection techniques contribute to additional decrease of n the TSS. ~__J Required Water Quality Volume for the western portion of the paved parking lot was calculated in accordance with the Massachusetts Stormwater ~ ~ Management Standards: VQw = (DQw / 12 in/ft) * Aimp *43560 SF/Ac VQw = (0.5in / 12 in/ft) * 0.427 Ac *43560 SF/Ac = 775 CF VQw =Required Water Quality Volume DQw =Water Quality Depth (0.5in) Aimp =Impervious area (0.94 Ac) The proposed storage capacity of the Vegetated Detention Basin exceeds the (~ Required Water Quality Volume providing adequate water quality treatment for the runoff. 4.5 Land Uses with Higher Potential Pollutant Loads(Standard 5) The use proposed does not differ from the current use of~the space and has no higher potential for pollution. 10 I I G:g13060\N01\Stormwater Management Report.doc J j ~~ ~~ ~_ _, _ _~ 4.6 Critical Areas (Standard 6 -Water Quality Treatments) This site does not lie within a critical area. One-half inch of runoff is the standard for treatment relative to water quality, but as stated prior, the proposed use will not create pollutants in excess of what exists today. 4.7 Redevelopment (Standard 7) `' Redevelopment projects are those that involve development, rehabilitation or _.~ expansion on previously developed sites provided the redevelopment results ~ in no net increase in impervious area. Furthermore, components of -~ redevelopment project, which include development of previously undeveloped ,.l sites, do not fall under Standard 7. In addition, redevelopment of previously developed sites must meet the Stormwater Management Standards to the maximum extent practicable. However, if it is not practicable to meet all the Standards, new (retrofitted or expanded) stormwater management systems ~ must be designed to improve existing conditions. _~ _ The project involves rehabilitation and paving of existing parking lot and ~ construction of a synthetic turf field in lieu of a natural turf field. There will -~ be increase in pavement under the post-development condition; however, the proposed pavement will not be subject to increased vehicular traffic. This is a redevelopment project. All standards are met to the maximum extent practicable. 4.8 Erosion and Sedimentation Controls (Standard 8) A Demolition and Erosion Control Plan is provided as part of the Notice of Intent application to the Conservation Commission. 4.9 Operation and Maintenance Plan (Standard 9) An Operation and Maintenance Plan is provided as part of the Notice of Intent application to the Conservation Commission. 4.10 Prohibition of Illicit Discharges Smith College, the Owner and User of the facility, assures that there will be not illicit discharges to the nearby wetlands from the proposed facility. 4.11 Floodplain (310 CMR 10.57) ~c ~ 'J 11 G:\7130601N01\Stormwater Management Report.doc _ _ _. _ .. ~_ n ~~ There shall not be any necessity for compensatory storage to be provided for flood storage volume was not lost. The proposed project does not include net cuts or fills changing substantially the existing topography within the Bordering Land Subject to Flooding of a brook or river. _I ~i ~-- ~J f -l it 12 ~ ~ G:\713060\NOI\Slormwater Management Report.doc .... D~ ~~ __ __ ATTACHMENT A: EXISTING CONDITIONS HYDROLOGY r I ,- ,, ,` ,.. v ~ \ .. .\ . - y , ~. .. , -~ t ' . .. : ~ ~ ~. s ~- s T' ~ r ~ ,. ` I"~ ,.. 5 ~ ~).. i• : ~ ~ r ..,., i i . ~ 1 ~. ~ ,~ ~~ ~ \~ ` ~ ~~ GRASS I I ; t , ~ :~, ~ 1 , ~.. ' ~ t _ ~~`I \,,. ~; ~ ,. .. r ~ \ , , ~ I C fry y.. t .. ~~ ~,,,,;1 ;. • ', •3 .•. •. ~. `i1 ~r ^ , - v ,.,. . .. ;. ` 4 .. n J ~\ x Y l -\\ I ------', , ° ~E Gala Associates, Inc. Engnwara and Plsnners 1fi3 LIBBEY PARKWAYIWEYNOVtH,su N~aY P 7fi7 376.64fifi F 781775 W67 xww 9anacam BpsWn Baltimore Ormntlo San fraraoo rha drpwing and the tln T one cmaW<I~o: ' • ~ t<amrea aedpeaa pr. prwraw is w• ' Asspclples, Inc and shd~ wr e• ar«w a u d In whale or pvt wAwwl tw• «p•a• rwrlllen Oermisaien al Cds aasocwt•w nc cpprw^iwom i , -. ~,~. ~ >. x i Q M ~ .~ • ~3 :. ~ ~ ., ,:. ~ ' . s ~ / LL_ U7 I F ,, • ~ . ' :. r / _ ~ r . ., § ~~ ) ~ ~ k f u: ~ ,... ~' W W ~ ' _ ... `, ~, ; t I GRAVEL -. ~~ ir ! , ~ ' atr ~o o J Q~~ J Q ~ .. .. ... .. ~ , ..,. i... _ r ~ u z ., ~ F.. o . ,.: ~ ; ~ ,. 4 Z > ',, ~ , .,~ f, ~ -' -~ - ~ ~I- ~ v w Q'~ a F~ . .. , ~~ ,. ~ o W , , . ~ _ • ~ ~N .., ~A \~' :~ ' t ~ - } } 4 .- ~Q - ~ N Q , ,~, - ... ~ a i ,.--• . ~ n , ~ ~ _ . I~ ' i '. .:, ~... A ..' : ~ ' - ,.: -_ .. i. i i . u i .. , i .: \ . ,a.. ~ _ ~i ~ d`L.V ~ . ,\ Y t - , N C ' - . .. _ , ,. , .: ,- .~ . ~ .. .. . ~, ~, ., ~ :. ' \ _ _ - w - , ' • ~ °' ~ .. - ~. ~ \ ~ ~ 1 .. ... - . . ~;.. ' ,. . „F. , ;', ~ " K \ ¢ ' -~. ~~ it : „ a ` y ,, ` .:j ~ ND. DALE DESCRIPOON t ~ ~ ~ '~ NT ,~ .; .. , ~ ~ ~~. ' ~ v PAVEME ' , . ~ GRAVEL \ ~ 1 ~ L~ , ,. ~; , Tc ,,. SUBAREA ,. , ., f , ,, .. ' ~ '~ ' : ~. ` . SUBAREA I .W ~ ~ .y ~ ,.,.. ~ , , ~, _ , ,. ; ~ ~~ . .. ,. : ~. ~ , - ... . \ r , \ ~ ., - k \ ~ ~"~ , „ ` . ~ , CARD FlL E 060 Pre Oev 71 '.• - ,.~ - t\ \ \ ~ .......... \ ~ to ~ .. , 4~ i RSA G DESIGNED BY' GM LJ _ .. ... W' '',. ., -' ' '` ` ~ ~. .~~ ~ \ ;"'~~ `~~ ~,. ' . ,:, \ ' DRAWN BY GAI ~. - .V \ ^ : ~ _ HECKEO BY C JT P 1 ~ ~ ~ • ~ <, . \ "/ ~ ~~ ~ DATE 11/10/06 '. - ~ '~, ., ~ :• ~ i ~,, : - '' DRAWING SCALE N,T.S. . , , ..;. 'i~ '..:~ ... .. GRAPHIC SCALE ~, ti o w' so' ~ ~' ~ \ .. ~ \ .__.__' _.~._...._ ..... .... SHEET TITLE i _ \\',.. s PRE DE ~ r ~ ~<~ ~ \ GI H DROLO C CONDITIONS I % ... ,. a~. ~ ; , ~ - PLAN n ~~ s v.;t ... - - .... t , ~ . _ . DRAWING N0. _ - i ~ . _ .. _ ___ _ _ _ -- _ . _, . _ __ .. ,. _ -- , . _ _ ... ., _ - N OI RTTRCHMENT _ . NOI-1 ~ • Paa6cr Bo, n7oso ; ~ Table of Contents i' ~ _, ~' -1 Table of Contents r- i ********************** MASTER SUMMARY ********************** rl y ............. Watershed....... Master Network Summar 1.01 _.__ *************** NETWORK SUMMARIES (DETAILED) *************** r I l Watershed....... 2 i- Executive Summary (Nodes) .......... 2.01 I Watershed....... 10 Executive Summary (Nodes) .......... 2.02 1 Watershed....... 50 Executive Summary (Nodes) .......... 2.03 Watershed....... 100 _ 1 Executive Summary (Nodes) .......... 2.04 ****************** DESIGN STORMS SUMMARY ************* ****** i ~_ Hampshire, MA... Design Storms ...................... 3.01 ********************** TC CALCULATIONS *************** ****** ~~ SUBAREA 10...... Tc Calcs ........................... 4.01 ff ******************** RUNOFF HYDROGRAPHS ******************** l~ f~~ f=~ Unit Hyd. Equations ................ 5.01 ' ~J ~_: ii ~ S/N: Bentley Systems, Inc. f -- Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 ~~ _, Type.... Master Network Summary Name.... Watershed I~ File.... G:\713060\Hydro\713060_Pre.ppw % \, Pag,.-1.01 MASTER DESIGN STORM SUMMARY Network Storm Collection: Hampshire, MA Total Depth Rainfall Return Event in Type ------ RNF -------- ID -------- ------------ 2 ------ 3.0000 ---------- Synthetic Curve TypeIII 24hr 10 4.5000 Synthetic Curve TypeIII 24hr 50 6.0000 Synthetic Curve TypeIII 24hr 100 6.4000 Synthetic Curve TypeIII 24hr MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft *OUT 10 JCT 2 .317 12.1000 3.90 *OUT 10 JCT 10 .654 12.1000 8.17 *OUT 10 JCT 50 1.029 12.1000 12.75 *OUT 10 JCT 100 1.133 12.1000 14.00 SUBAREA 10 AREA 2 .317 12.1000 3.90 SUBAREA 10 AREA 10 .654 12.1000 8.17 SUBAREA 10 AREA 50 1.029 12.1000 12.75 SUBAREA 10 AREA 100 1.133 12.1000 14.00 ', ~-~ S/N; Bentley Systems, Inc. I~ Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 ~ ~ I___ _~ i i~ ~ Type.... Executive Summary (Nu.. s) Pages-L.O1 Name.... Watershed Event: 2 yr ~ File.... G:\713060\Hydro\713060_Pre.ppw J Storm... TypeIII 24hr Tag: 2 NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) DEFAULT Design Storm File,ID = Hampshire, MA Storm Tag Name = 2 ----------- --------------- -------------- -------------------- Data Type, File, ID -------- = Synthetic Storm TypeIII 24hr Storm Frequency = 2 yr Total Rainfall Depth= 3.0000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs HYG Vol Qpeak Qpeak Max WSEL Node ID Type ac-ft Trun. hrs cfs ft ------ --------- ----------------- Outfall OUT 10 ---- ---------- - JCT .317 - --------- 12.1000 -- 3.90 SUBAREA 10 AREA .317 12.1000 3.90 --~ i_~ ,,, _~ ~J S/N: Bentley Systems, Inc. Bentle PondPack (10 00 027 00) 10:01 AM 12/2/2008 y ~, _ I ~___, Type.... Executive Summary (N`_... ls) Pay _.x.02 Name.... Watershed Event: 10 yr ' File.... G:\713060\Hydro\713060_Pre.ppw Storm... TypeIII 24hr Tag: 10 NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) DEFAULT Design Storm File,ID = Hampshire, MA -ll Storm Tag Name = -_--10-_-_------ ~__1 ---------------------- ------------------------------ Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 10 yr ~ Total Rainfall Depth= 4.5000 in [~, Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs ~~ HYG Vol Qpeak Qpeak Max WSEL ~._~ Node ID Type ac-ft Trun. hrs cfs ft ----------------- ---- ---------- -- --------- -------- --------- ~ Outfall OUT 10 JCT .654 12.1000 8.17 L_~ SUBAREA 10 AREA .654 12.1000 8.17 _~ ~_ !~ ~~ S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 -~ II~ ~.~ ~s ' \ g 03 ) ~~ Type .... Executive Summary (N ~__ Pa . Name.... Watershed Event: 50 yr l File.... G:\713060\Hydro\713060 Pre.ppw Storm... TypeIII 24hr Tag: 50 I~ ~.~ NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; ' L=Left; R=Rt; LR=Left & Rt) ~ DEFAULT Design Storm File,ID = Hampshire, MA i Storm Tag Name = ___-50---------- ----------- Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 50 yr Total Rainfall Depth= 6.0000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs _ ir~ i 11 HYG Vol Qpeak Qpeak Max WSEL . , Node ID Type ac-ft T ------- run. hrs - --------- - cfs ft ------- --------- ----------------- ---- --- I Outfall OUT 10 JCT 1.029 - 12.1000 12.75 l SUBAREA 10 AREA 1.029 12.1000 12.75 ,__~ ~__' S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 I -J (~~ (~ Type.... Executive Summary (N.__es) Pag,__L.04 Name.... Watershed Event: 100 yr File.... G:\713060\Hydro\713060 Pre.ppw _ Storm... TypeIII 24hr Tag: 100 r ~~ NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) I I DEFAULT Design Storm File,ID = Hampshire, MA 100 Name _ l Storm Tag ----__ _ - _ Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 100 yr Total Rainfall Depth= 6.4000 in I Duration Multiplier = 1 L _ Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs HYG Vol I Qpeak Qpeak Max WSEL Node ID Type ac-ft Trun. hrs ---- -- --------- - cfs ft ------- --------- ----------------- ---- ------ ~ Outfall OUT 10 JCT 1.133 12.1000 14.00 ~ SUBAREA 10 AREA 1.133 12.1000 14.00 J IJ I~ - i _ _. _a - --- S/N: Bentley PondPack (10.00.027.00) Bentley Systems, Inc. 10:01 AM 12/2/2008 /r~~\ r~ i I i '~ ~ Type.... Design Storms ~'~--=~ Pay~~_-3.01 Name.... Hampshire, MA r I~_ File.... G:\713060\Hydro\713060_Pre.ppw ' Title... Project Date: 11/18/2008 Project Engineer: gm Project Title: Watershed Project Comments: DESIGN STORMS SUMMARY Design Storm File,ID = Hampshire, MA Storm Tag Name = 2 l Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 2 yr Total Rainfall Depth= 3.0000 in n Duration Multiplier = 1 Il I Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs Storm Tag Name = 10 Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 10 yr Total Rainfall Depth= 4.5000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs Storm Tag Name = 50 Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 50 yr Total Rainfall Depth= 6.0000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs Storm Tag Name = 100 Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 100 yr Total Rainfall Depth= 6.4000 in Duration Multiplier = 1 Resulting Duration = 29.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs l~ ~~ S/N: __1 Bentley PondPack (10.00.027.00) ,l _L L-----~--- _____-_- ---.,..___.._-_---- ___-- -- 10:01 AM Bentley Systems, Inc. 12/2/2008 ~~ Type.... Tc Calcs ~_~ Pay._ 4.01 Name.... SUBAREA 10 _~ I _j File.... G:\713060\Hydro\713060_Pre.ppw f_~ TIME OF CONCENTRATION CALCULATOR ............................................................. II-~ ........................................................................ ------------------------------------------------------------------------- r l_ Segment #1: Tc: TR-55 Sheet ~~ Mannings n .0220 Hydraulic Length 164.00 ft 2yr, 24hr P 3.0000 in Slope .010000 ft/ft ~~ Avq.Velocity .64 ft/sec Segment #1 Time: .0712 hrs 1 ------------------------------------------------------------------------ ~~ Segment #2: Tc: TR-55 Channel 1 Flow Area 4.9100 sq.ft 11 Wetted Perimeter 7.85 ft Hydraulic Radius .63 ft Slope .010000 ft/ft -~ Mannings n .0120 Hydraulic Length 300.00 ft Avg.Velocity 9.08 ft/sec `1 Segment #2 Time: .0092 hrs ~__ ------------------------------------------------------------------------ Total Tc: .0804 hrs Calculated Tc < Min.Tc: Use Minimum Tc... Use Tc = .0833 hrs ------------------------ ------------------------ i __ ~ S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 i__1-----------..__._.__~ ----_.--- __,_..._ _._..------___.._ ----__.___... _~ Type.... Tc Calcs ~ . Name.... SUBAREA 10 File.... G:\713060\Hydro\713060 Pre.ppw ~~~ ~ - Faye 4.02 ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ___= SCS TR-55 Sheet Flow _______________________________ Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4)) Where: Tc = Time of concentration, hrs n =Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, a ___= SCS Channel Flow ________________________ R = Aq / Wp V = (1.49 * (R**(2/3)) * (Sf**-0.5)) / n Tc = (Lf / V) / (3600sec/hr) Where: R =Hydraulic radius Aq = Flow area, sq.ft. Wp = Wetted perimeter, ft V = Velocity, ft/sec Sf = Slope, ft/ft n =Mannings n Tc = Time of concentration, hrs Lf = Flow length, ft '_~ '~ S/N; Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 i I I I Type.... Unit Hyd. Equatiori~-= Name.... File.... G:\713060\Hydro\713060 Pre.ppw I - I _, ~\ ) Page 5.01 SCS UNIT HYDROGRAPH METHOD (Computational Notes) DEFINITION OF TERMS: ------------------------------------------------ At = Total area (acres): At = Ai+Ap ~ Ai = Impervious area (acres) LI Ap = Pervious area (acres) CNi = Runoff curve number for impervious area CNp = Runoff curve number for pervious area floss = f loss constant infiltration (depth/time) ~~ gKs = Saturated Hydraulic Conductivity (depth/time) Md = Volumetric Moisture Deficit Psi = Capillary Suction (length) ~~ hK = Horton Infiltration Decay Rate (time^-1) fo = Initial Infiltration 'Rate (depth/time) fc = Ultimate(capacity)Infiltration Rate (depth/time) Ia = Initial Abstraction (length) dt = Computational increment (duration of unit excess rainfall) Default dt is smallest value of 0.1333Tc, rtm, and th (Smallest dt is then adjusted to match up with Tp) UDdt = User specified override computational main time increment ~J (only used if UDdt is => .1333Tc) Il D(t) = Point on distribution curve (fraction of P) for time step t K = 2 / (1 + (Tr/Tp)): default K = 0.75: (for Tr/Tp = 1.67) Ks = Hydrograph shape factor ~ = Unit Conversions * K: _ ((1hr/3600sec) * (1ft/12in) * ((5280ft)**2/sq.mi)) * K Default Ks = 645.333 * 0.75 = 484 Lag = Lag time from center of excess runoff (dt) to Tp: Lag = 0.6Tc P = Total precipitation depth, inches Pa(t) = Accumulated rainfall at time step t Pi(t) = Incremental rainfall at time step t qp = Peak discharge (cfs) for lin. runoff, for 1hr, for 1 sq.mi. _ (Ks * A * Q) / Tp (where Q = lin. runoff, A=sq.mi.) Qu(t) = Unit hydrograph ordinate (cfs) at time step t Q(t) = Final hydrograph ordinate (cfs) at time step t Rai(t)= Accumulated runoff (inches) at time step t for impervious area Rap(t)= Accumulated runoff (inches) at time step t for pervious area Rii(t)= Incremental runoff (inches) at time step t for impervious area Rip(t)= Incremental runoff (inches) at time step t for pervious area R(t) = Incremental weighted total runoff (inches) Rtm = Time increment for rainfall table Si = S for impervious area: Si = (1000/CNi) - 10 Sp = S for pervious area: Sp = (1000/CNp) - 10 t = Time step (row) number Tc = Time of concentration Tb = Time (hrs) of entire unit hydrograph: Tb = Tp + Tr Tp = Time (hrs) to peak of a unit hydrograph: Tp = (dt/2) + Lag Tr = Time (hrs) of receding limb of unit hydrograph: Tr = ratio of Tp 'J ~~ S/N: ~ Bentley PondPack (10.00.027.00) _. I-- -- ---._._ _ ___ ----..____...-.__._ ~____ __ .- -- --._._...----- ~_~ Bentley Systems, Inc. 10:01 AM 12/2/2008 i"l '_._I Type.... Unit Hyd. Equation~__! Name.... '~1 File.... G:\713060\Hydro\713060_Pre.ppw I PRECIPITATIO Column (1): Column (2): Column (3): Column (4): ~-. Page 5.02 SCS UNIT HYDROGRAPH METHOD (Computational Notes) ----------------------------------------------- for time step t = Point on distribution curve for time step t = Pa(t) - Pa(t-1): Col.(4) - Preceding Col.(4) = D(t) x P: Col.(2) x P N: --- Time D(t) Pi (t) Pa (t) PERVIOUS AREA RUNOFF (using SCS Runoff CN Method) ------------------------ Column (5): Rap(t) = Accumulated pervious runoff for time step t If (Pa(t) is <= 0.2Sp) then use: Rap(t) = 0.0 If (Pa(t) is > 0.2Sp) then use: Rap(t) _ (Col.(4)-0.2Sp)**2 / (Col.(4)+0.8Sp) Column (6): Rip(t) = Incremental pervious runoff for time step t Rip (t) = Rap(t) - Rapt-1) Rip(t) = Col.(5) for current row - Col.(5) for preceding row. IMPERVIOUS AREA RUNOFF --------------------------------------------------- Column (7 & 8)... Did not specify to use impervious areas. lJ INCREMENTAL WEIGHTED RUNOFF: --------------------------------------------- J Column (9): R(t) _ (Ap/At) x Rip(t) (Ai/At) x Rii(t) R(t) _ (Ap/At) x Col.(6) + (Ai/At) x Col.(8) SCS UNIT HYDROGRAPH METHOD: ---------------------------------------------- Column (10): Q(t) is computed with the SCS unit hydrograph method using R() and Qu(). I__) J S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 10:01 AM 12/2/2008 i' _I_.__..__.--------__-___..__.___.____------_____..__.___.__~__........_T.-__.__,._.__._.___..__...___._.___..._.___.____..-----.___..---__-__-.___..__--- t__J Appendix A ~~ Index of Starting Page Numbers for ID Names ----- H ----- Hampshire, MA... 3.01 ----- S ----- SUBAREA 10... 4.01 ----- W ----- Watershed... 1.01, 2.01, 2.02, 2.03, 2.04 ~~ A-1 _, S/N: Bentley PondPack (10.00.027.00) ~, _ I L_.._._.._~._.__ ____--------- _._,_.____._~___ ~__.___..__-- ~J 10:01 AM I Bentley Systems, Inc. 12/2/2008 D~ ~-~, ~;_-~ . ATTACHMENT B: POST DEVELOPMENT HYDROLOGY ~, I____.____ ___-_-- ----__---------_-.__ _.__ ____ _. ____._ ____ _____ ___`__.._-----.~______.._ _--- ---_~._ __ __----_._.__-----. ___ ~__J I 1 _ ~~` Gale Assaclales, Inc. Engineers and Planners 163 LIB6EY PARI(WAYWEYMOIITH, MA 02169 P7B1.77fi.64fi6 F 761.376,6467 6vwe.9anasom Boston EaOimore [Idaho San Frantis Thle drawing and the daslgn wd consWcllc! lealuree 9scloeed we proprlelory lc Gale Aesoclotes, Inc. and shall not 6e altered w u ed In whole m Darl wllhaul the :sprees rwrlNsn permission of Gala Assaclotes, Inc. CaPMigh1o2006 ,J O IJJ ~ !n W O ~ F- Q ~ UZ W ~ WSW ~ U ~ O 2>wZ ?~f .; _ to 1 `v t I •., 4 ~-- •. . ,. ., ~ ,. \. ~8 F --- ~\ _ ,. M rt «` , i ;. .- n' y. i l i / '. \\ ~.' ~ ., \ ~ I~ X36... / ~~ // / ND. DATE DESCRIPTION y , , ~s~~ \; \, \.., ! ~£ ~ s / / // ;~ :,•:. \' ~~B AREA II '~ ~' ~ ? \ ~ 5~,~ \~ \; \ \:\ ~\~ \\ VIA // , j; )f ~ - ~ \ \ ' ~\ ~' o sere +' F\\ \ y ~'~~~\ -.. \< \` \~ IV/ / ~/ / /'/ // / ~/ ' U ~ ~ ~ X137 OBG \ ' ~\\ `\ , , / . ' ' ~., .r \~,~V LIYILIV '• ~Y`r ~ ~~\ ~Y \.;. e.: ~59. \\~': \\\ \0.5R \lll /~ / / 0~ , / : ~ K ' / \ ~ I.. \ \\ \ \ / /. \ y~ ~; `~ 177 O1C ~. ; .! .,. :.., \\ ,... ~\.\ ~\\ ...".~,\. ........_.a.,_---C- \ \\..... /,,... / _". / / % ~ // / ! ~.:..: w ~ 137 G ...• \ ~~ \ ..,,,. \ _... II / _ . / ~ / / ILJI ~ 3 \ ~ ~. \ .... \. \ .. / ,,/ ~ / / ~\ \ ~ \ _ , ~ .... \ .... "' , \~ Ib / ~/' s/ / CADO FILE 713 al Dev .... _. ' + '~. ... . ........ ......... .... .. ........ ,. \ IA 4016 \ ~1~ ~ \\\. \\\ \\\ \~\4 9 \\ \•'• \\\ III /' r/,..: // / /' / .~ DESIGNED BY GM 060 / .. / \ ~.., \ / ~ DRAWN BY GM ..... ... - ,:, ~; ~, ; ~ `,\\,: '. ,, \4 \\ ; \\ \\ ~U T1-LI!,~,' ~ ~:7 Y.~IFT~ET,IC CHEGRED BY PJT `., ,.. '~' ~ sd •.. \ \ \ \ \ \ . \\ ~ \\ I~ / / ~.. DATE 11/10/08 \ •; \ \ \ / - .....~ •, •., ! .. ,.\ \'. \ \ \ ~ SCALE N.T.S. .. - ,• \ ..: '. ...\.J \... •.~~\\ \ \\ \ \ \ II .. / / ., .. // I DRAWING ~ \ \ \ ~\\ \ \ 7B \ \ II , / / / , // GRAPHIC SCALE n \ , / / !" t ~~ \'~ .I ~ , \\ \ ~ ~ \ - ~-;~I t // , ~~. /' // SHEET TITLE / / ',. '~J ~ ~ ~ i~\ ~ -`-~ `\\ -~~\\ \\\ \\ \\ pl'/ ,'~ ~/ ~ ~~ ,'~ ,'/ POST DEV. ~\ I ~\ \\ \\ ~\II / C DROTONIS \ \• \ ; \ , \ II ' ~- ~ ~ PLAN ~ \ L ' / r - -, •~- .,, "- `r 1. ~ I DRAWING N0. 7 ~. ._ ~ - .. • . .. _ - - - " N 2 .. ~, ~L,---____.___ ~_____ ._...__~ __.:~m_;_ _.._.__~..---'---__.__.____ _______."__ ._ ______.-___ ..____ _.___. _ _ _.._ : _.._.._..~ ___.._.._ ____ .__._._ .________ _ _. _.__. _..__.____..._...__.___ __. _.".__ N0IRTTRCHMENT _. __~___ . _ ._ PAOSELI N0.713L60 ~, _..... i ~ Table of Contents ~~~ ~~ _; I _I f~l Table of Contents I-_1 ********************** MASTER SUMMARY ********************** ~~ Watershed....... Master Network Summary ............. 1.01 *************** NETWORK SUMMARIES (DETAILED) *************** ~~ Watershed....... Dev 2 Executive Summary (Nodes) .......... 2.01 I~ Watershed....... Dev 10 Executive Summary (Nodes) .......... 2.02 r-~ Watershed....... Dev 50 u Executive Summary (Nodes) .......... 2.03 Watershed....... Dev100 ~-- Executive Summary (Nodes) .......... 2.04, .J Network Calcs Sequence ............. 2.05 (1 ****************** DESIGN STORMS SUMMARY ******************* ~J 11 Hampshire, NIA... Design Storms ...................... 3.01 u ********************** ********************* TC CALCULATIONS -J SUBAREA 1....... Tc Calcs ........................... 4.01 i SUBAREA 2....... Tc Calcs ........................... 4.03 I SUBAREA 3....... Tc Calcs ........................... 4.07 ~~JJJ *********************** POND ROUTING *********************** LJ l DET POND........ Pond E-V-Q Table ................... 5.01 _J J '~J i I IJ S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 - I ~---__..--- --. ___-____..-----_ --------___~_.__.`--------- -_____~_-------_. ~.._.....____~___._ __~~._.__.-------_--- ----------- ',_J ~ ~~ Table of Contents ~ i,,, Table of Contents (continued) DET POND OUT Dev 10 Pond Routing Summary ............... 5.03 DET POND OUT Dev 50 Pond Routing Summary ............... 5.04 DET POND OUT Dev100 Pond Routing Summary ............... 5.05 GR STORAGE OUT Dev 10 Pond Routing Summary ............... 5.06 GR STORAGE OUT Dev 50 Pond Routing Summary ............... 5.07 GR STORAGE OUT Dev100 Pond Routing Summary ............... 5.08 ~~ ~ -~ S/N: Bentley PondPack (10.00.027.00) i_ ~-..._ -- ------- ~------- --- ----- -- -.._, ___------ - - ~~ Bentley Systems, Inc. 9:25 AM 12/4/2008 ii ~, i Type.... Master Network Sumr'~ l P~~1.01 Name.... Watershed ("~ File.... G:\713060\Hydro\713060 Post.ppw II _~ _I MASTER DESIGN STORM SUMMARY ~~_ _I Network Storm Collection: Hampshire, MA r- Total I- Depth Rainfall Return Event in Type RNF ID Il ---------- ------ ---------------- Dev 2 3.0000 Synthetic Curve -------- TypeIII -------- 24hr ' Dev 10 4.5000 Synthetic Curve TypeIII 24hr Dev 50 6.0000 Synthetic Curve TypeIII 24hr f~1 Dev100 6.4000 Synthetic Curve TypeIII 24hr ~ MASTER NETWORK SUMMARY SCS Unit Hydrograph Method l _.~ (*Node=Outfall; +Node=Diversion;) f-1 (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun -- -- hrs - - cfs ft ac-ft ---- DET --------- POND ---- IN ---- POND ------ 2 -------- .142 - -- ---- 12.1000 -------- 1.57 -------- ------------ DET POND IN POND 10 .221 12.1000 2.39 DET POND IN POND 50 .301 12.1000 3.21 DET POND IN POND 100 .322 12.1000 3.43 DET POND OUT POND 2 .141 12.2000 .83 133.55 .040 DET POND OUT POND 10 .221 12.2000 1.38 133.73 .055 DET POND OUT POND 50 .300 12.2000 1.93 133.89 .069 DET POND OUT POND 100 .322 12.2000 2.07 133.93 .073 GR STORAGE IN POND 2 .211 12.5000 1.36 GR STORAGE IN POND 10 .451 12.5000 3.04 GR STORAGE IN POND 50 .722 12.5000 4.91 GR STORAGE IN POND 100 .798 12.5000 5.42 I~ ~ -I S/N: Bentley PondPack (10.00.027.00) ~, ~-_1 9:25 AM Bentley Systems, Inc. 12/4/2008 Type.... Master Network Sum Name.... Watershed File.... G:\713060\Hydro\713060_Post.ppw P~~.__. ~1 .02 MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun ----- -- hrs --------- cfs -------- ft -------- ac-ft ------------ ------------- GR STORAGE ---- OUT ---- POND ------ 2 ----- .199 13.5000 .32 134.76 .084 GR STORAGE OUT POND 10 .420 13.2000 .96 134.88 .175 GR STORAGE OUT POND 50 .666 13.1000 1.82 135.00 .269 GR STORAGE OUT POND 100 .734 13.0500 2.07 135.03 .294 *MILL RIVER JCT 2 .399 12.1000 1.37 *MILL RIVER JCT 10 .733 12.1000 2.31 *MILL RIVER JCT 50 1.092 12.1000 3.27 *MILL RIVER JCT 100 1.190 12.1500 3.56 SUBAREA 1 AREA 2 .142 12.1000 1.57 SUBAREA 1 AREA 10 .221 12.1000 2.39 SUBAREA 1 AREA 50 .301 12.1000 3.21 SUBAREA 1 AREA 100 .322 12.1000 3.43 SUBAREA 2 AREA 2 .059 12.1000 .66 SUBAREA 2 AREA 10 .092 12.1000 1.00 SUBAREA 2 AREA 50 .126 12.1000 1.34 SUBAREA 2 AREA 100 .134 12.1000 1.43 SUBAREA 3 AREA 2 .211 12.5000 1.36 SUBAREA 3 AREA 10 .451 12.5000 3.04 SUBAREA 3 AREA 50 .722 12.5000 4.91 SUBAREA 3 AREA 100 .798 12.5000 5.42 S/N: Bentley PondPack (10.00.027.00) 9:25 AM Bentley Systems, Inc. 12/4/2008 _~ Type.... Executive Summary (~~~s) Pa~ ~JL.01 Name.... Watershed Event: 2 yr File.... G:\713060\Hydro\713060_Post.ppw Storm... TypeIII 24hr Tag: Dev 2 NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) DEFAULT Design Storm File,ID = Hampshire, MA ~1 u ~ ~__ Storm Tag Name = Dev 2 ---------- --------------- --------- ----- -------------------- Data Type, File, ID -------- = Synthe - tic Storm TypeIII 24hr Storm Frequency = 2 yr Total Rainfall Depth= 3.0000 in Duration Multiplier = 1 Resulting Duration = 24.000 0 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs HYG Vol Qpeak Qpeak Max WSEL Node ID Type ac-ft Trun. hrs cfs ft DET POND IN POND .142 - 12.1000 1.57 DET POND OUT POND .141 12.2000 .83 133.55 GR STORAGE IN POND .211 12.5000 1.36 GR STORAGE OUT POND .199 13.5000 .32 134.76 Outfall MILL RIVER ~JCT .399 12.1000 1.37 SUBAREA 1 AREA .142 12.1000 1.57 SUBAREA 2 AREA .059 12.1000 .66 SUBAREA 3 AREA .211 12.5000 1.36 S/N: Bentley PondPack (10.00.027.00) 9:25 AM Bentley Systems, Inc. 12/4/2008 _,i j .-~. Type.... Executive Summary (~ ~s) ~ Pa~_ .02 Name.... Watershed Event: 10 yr 'l File.... G:\713060\Hydro\713060_Post.ppw 'i,.l Storm... TypeIII 24hr Tag: Dev 10 I L_-.~ NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) 1 ~I DEFAULT Design Storm File,ID = Hampshire, MA .- 10---_ Storm Tag Name = Dev ~ --- - Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 10 yr Total Rainfall Depth= 4.5000 in I ~ Duration Multiplier = 1 ~ Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End = 24.0000 hrs r HYG Vol Qpeak Qpeak Max WSEL J ~- Node ID Type ac-ft Trun. hrs - -- --------- cfs -------- ft --------- 1 ----------------- ---- --------- DET POND IN POND .221 12.1000 2.39 DET POND OUT POND .221 12.2000 1.38 133.73 ~-I GR STORAGE IN POND .451 12.5000 3.04 GR STORAGE OUT POND .420 13.2000 .96 134.88 Outfall MILL RIVER JCT .733 12.1000 2.31 SUBAREA 1 AREA .221 12.1000 2.39 ~-- SUBAREA 2 AREA .092 12.1000 1.00 SUBAREA 3 AREA .451 12.5000 3.04 l I ~J ,~ I %~ _J S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 -~ ~i LJ Type.... Executive Summary (r^ =s) Name.... Watershed File.... G:\713060\Hydro\713060 Post.ppw Storm... TypeIII 24hr Tag: Dev 50 ~-. P ~__ ,~.03 Event: 50 yr NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) DEFAULT Design Storm File,ID = Hampshire, MA - Storm Tag Name = Dev 50 ) ~- Data Type, File, ID = Synthet ic Storm TypeIII 24hr Storm Frequency = 50 yr Total Rainfall Depth = 6.0000 in I I Duration Multiplier = 1 _ Resulting Duration = 24.0000 hrs Resulting Start Time = .0000 h rs Step= .1000 hrs End= 24.0000 hrs HYG Vol Qpeak Qpeak Max WSEL Node ID Type ac-ft Trun. hrs - cfs - ft -- ((ll ----------------- DET POND IN ---- -- POND -------- .301 - --------- 12.1000 ---- --- 3.21 -- ----- I DET POND OUT POND .300 12.2000 1.93 133.89 _ IIJJ GR STORAGE IN POND .722 12.5000 4.91 GR STORAGE OUT POND .666 13.1000 1.82 135.00 Outfall MILL RIVER JCT 1.092 12.1000 3.27 SUBAREA 1 AREA .301 12.1000 3.21 '- SUBAREA 2 AREA .126 12.1000 1.34 SUBAREA 3 AREA .722 12.5000 4.91 iJ ~l l~ i ...:- _ __ S/N: Bentley PondPack (10.00.027.00) 9:25 AM Bentley Systems, Inc. 12/4/2008 -~ I, ~ Type.... Executive Summary ~~~es) P~_~.~2.04 Name.... Watershed Event: 100 yr ~~ File.... G:\713060\Hydro\713060_Post.ppw II Storm... TypeIII 24hr Tag: Dev100 NETWORK SUMMARY -- NODES (Trun.= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left & Rt) DEFAULT Design Storm Fi1e,ID = Hampshire, MA l ~__~ __ '~~. Storm Tag Name = Dev100 - ----- - - -------------------- Data Type, File, ID --------- = Synthet -- ------- ic Storm ------- - - TypeIII 24hr --------- -- -- Storm Frequency = 100 yr Total Rainfall Depth = 6.4000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 h rs Step= .1000 hrs End= 24.0000 hrs HYG Vol Qpeak Qpeak Max WSEL Node ID Type ac-ft Trun. hrs -- - cfs ft ----------------- DET POND IN ---- -- POND - ----- - .322 - ------ -- - 12.1000 ------- 3.43 --------- DET POND OUT POND .322 12.2000 2.07 133.93 GR STORAGE IN POND .798 12.5000 5.42 GR STORAGE OUT POND .734 13.0500 2.07 135.03 Outfall MILL RIVER JCT 1.190 12.1500 3.56 SUBAREA 1 AREA .322 12.1000 3.43 SUBAREA 2 AREA .134 12.1000 1.43 SUBAREA 3 AREA .798 12.5000 5.42 S/N: Bentley PondPack (10.00.027.00) 9:25 AM Bentley Systems, Inc. 12/4/2008 Type.... Network Calcs Sequ,._-~e Name.... Watershed File.... G:\713060\Hydro\713060 Post.ppw Storm... TypeIII 24hr Tag: Dev100 f^1 2.05 Event: 100 yr NETWORK RUNOFF NODE SEQUENCE Runoff Data Apply to Node Receiving Link SCS UH SUBAREA 1 Subarea SUBAREA 1 Add Hyd SUBAREA 1 SCS UH SUBAREA 3 Subarea SUBAREA 3 Add Hyd SUBAREA 3 SCS UH SUBAREA 2 Subarea SUBAREA 2 Add Hyd SUBAREA 2 ~ -~ S/N: Bentley PondPack (10.00.027.00) ,, _. L._ ._... _._ ~ _._ _..__.__~______ .._.__.~__._...__ __.._.e.______ i__~ Bentley Systems, Inc. 9:25 AM 12/4/2008 ~~~ ~~ Type.... Network Calcs Sequ~~~~e ~ b-,;~ 2.06 Name.... Watershed Event: 100 yr I~~ File.... G:\713060\Hydro\713060_Post.ppw ~ Storm... TypeIII 24hr Tag: Dev100 NETWORK ROUTING SEQUENCE Link Operation ------------------------- UPstream ---------- Node ------------- ---- DNstream --------- Node ------------ -- ------------------------- Add Hyd ADDLINK 20 ---------- Subarea ------------- SUBAREA 1 ---- --------- Pond ------------ DET POND -- IN POND ROUTE TOTAL OUTFLOW ... Total Pond Outflow Pond DET POND IN Outflow DET POND OUT SET POND ROUTING LINK TO TOTAL POND OUTFLOW... Outlet ROUTE 10 Outflow DET POND OUT Jct MILL RIVER Add Hyd ADDLINK 10 Subarea SUBAREA 3 Pond GR STORAGE IN POND ROUTE INFILTRATION AND TOTAL OUTFLOW... Infiltration Pond GR STORAGE IN Infilt. GR STORAGE INF Total Pond Outflow Pond GR STORAGE IN Outflow GR STORAGE OUT SET POND ROUTING LINK TO TOTAL POND OUTFLOW... Outlet ROUTE 20 Outflow GR STORAGE OUT Jct MILL RIVER Add Hyd ADDLINK 30 Subarea SUBAREA 2 Jct MILL RIVER ~'~J S/N: Bentley PondPack (10.00.027.00) _,~' l.___._____.__ __._._______~___________~~____. ~., Bentley Systems, Inc. 9:25 AM 12/4/2008 Type.... Design Storms ~~~ F. ,,3 3.01 Name.... Hampshire, MA File.... G:\713060\Hydro\713060_Post.ppw Title... Project Date: 11/18/2008 Project Engineer: gm Project Title: Watershed Project Comments: DESIGN STORMS SUMMARY Design Storm File,ID = Hampshire, MA Storm Tag Name = Dev 2 Data Type, File, ID = Synthetic Storm TypeIII 24hr ' Storm Frequency = 2 yr Total Rainfall Depth= 3.0000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs Storm Tag Name = Dev 10 Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = '10 yr Total Rainfall Depth= 4.5000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs Storm Tag Name = Dev 50 Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 50 yr Total Rainfall Depth= 6.0000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs Storm Tag Name = Dev100 Data Type, File, ID = Synthetic Storm TypeIII 24hr Storm Frequency = 100 yr Total Rainfall Depth= 6.4000 in Duration Multiplier = 1 Resulting Duration = 24.0000 hrs Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs fl S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 Type.... Tc Calcs Name.... SUBAREA 1 File.... G:\713060\Hydro\713060_Post.ppw P .~.~ 4.01 ........................................................................ ........................................................................ TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: TR-55 Sheet Mannings n .0120 Hydraulic Length 50.00 ft 2yr, 24hr P 3.0000 in Slope .010000 ft/ft Avg.Velocity .82 ft/sec Segment #1 Time: .0169 hrs Segment #2: Tc: TR-55 Shallow Hydraulic Length 60.00 ft Slope .010000 ft/ft Paved Avg.Velocity 2.03 ft/sec Segment #2 Time: .0082 hrs ------------------------------------------------------------------------ ------------------------- ------------------------- Total Tc: .0251 hrs Calculated Tc < Min.Tc: Use Minimum Tc... Use Tc = .0833 hrs '~ S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 ~~ ''-.J ~i 1, r`- Type .... Tc Calcs l ^! !___, ~ 4 . 02 Name.... SUBAREA 1 File.... G:\713060\Hydro\713060 Post.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ___= SCS TR-55 Sheet Flow _______________________________ '~_J Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4)) Where: Tc = Time of concentration, hrs r n = Mannings n 11 Lf = Flow length, ft ~-~~ P = 2yr, 24hr Rain depth, inches Sf = Slope, °s ~ - ___= SCS TR-55 Shallow Concentrated Flow ________________ ~ Unpaved surface: V = 16.1345 * (Sf**0.5) Paved surface: -, V = 20.3282 * (Sf**0.5) ~- Tc = (Lf / V) / (3600sec/hr) r- Where: V =Velocity, ft/sec I Sf = Slope, ft/ft L j Tc = Time of concentration, hrs Lf = Flow length, ft l__1 J II _.") !`J S/N: Bentley PondPack (10.00.027.00) r _L 1-.__-------.,___~__.._~.__._.~..___~_._.m._._.,_._._. ~. i Bentley Systems, Inc. 9:25 AM 12/4/2008 ~\ Type.... Tc Calcs ( l Name.... SUBAREA 2 File.... G:\713060\Hydro\713060 Post.ppw h~ 4.03 ........................................................................ ........................................................................ TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: TR-55 Sheet Mannings n .0120 Hydraulic Length 50.00 ft 2yr, 24hr P 3.0000 in Slope .010000 ft/ft Avg.Velocity .82 ft/sec Segment #1 Time: .0169 hrs Segment #2: Tc: TR-55 Shallow Hydraulic Length 150.00 ft Slope .010000 ft/ft Paved Avg.Velocity 2.03 ft/sec Segment #2 Time: .0205 hrs ----------------------------------------------------------------------- Segment #3: Tc: TR-55 Channel Flow Area .7850 sq.ft Wetted Perimeter 3.14 ft Hydraulic Radius .25 ft Slope .005000 ft/ft Mannings n .0120 Hydraulic Length 150.00 ft Avg.Velocity 3.48 ft/sec Segment #3 Time: .0120 hrs ------------------------------------------------------------------------ S/N: Bentley PondPack (10.00.027.00) 9:25 AM Bentley Systems, Inc. 12/4/2008 L._~.._._..._ .. ~.~ ~1 Type.... Tc Calcs ( / Name.... SUBAREA 2 File.... G:\713060\Hydro\713060 Post.ppw ~~~ 4 . 0 4 Segment #4: Tc: TR-55 Channel Flow Area 3.1400 sq.ft Wetted Perimeter 6.28 ft Hydraulic Radius .50 ft Slope .012900 ft/ft Mannings n .0120 Hydraulic Length 243.00 ft Avg.Velocity 8.88 ft/sec f ~~ Segment-#4-Time_-----_0076-hrs ------------------------------------------------ --- ------------------------ ------------------------ Total Tc: .0570 hrs Calculated Tc < Min.Tc: Use Minimum Tc... Use Tc = .0833 hrs 'J S/N;_ Bentley PondPack (10.00.027.00) I_ ~: _i " 9:25 AM Bentley_Systems, .Inc. 12/4/2008 Type.... Tc Calcs Name.... SUBAREA 2 File.... G:\713060\Hydro\713060_Post.ppw ------------------------------------------------------------------------ Tc Equations used... ------------------------------------------------------------------------ ___= SCS TR-55 Sheet Flow ______________________________________________ Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4)) Where: Tc = Time of concentration, hrs n = Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, o ___= SCS TR-55 Shallow Concentrated Flow _______________________________ Unpaved surface: V = 16.1345 * (Sf**0.5) Paved surface: V = 20.3282 * (Sf**0.5) Tc = (Lf / V) / (3600sec/hr) Where: V = Velocity, ft/sec Sf = Slope, ft/ft Tc = Time of concentration, hrs Lf = Flow length, ft ~~ R~ ,,. 4.05 S/N: Bentley PondPack (10.00.027.00) 9:25 AM Bentley Systems, I_nc. 12/4/2008 II -i-~~ ,__. _.~ i I ~~ ~ j Type.... Tc Calcs ~. ~ P~~4.06 ___ Name.... SUBAREA 2 File.... G:\713060\Hydro\713060_Post.ppw. ___= SCS Channel Flow __________________________________________________ R = Aq / Wp V = (1.49 * (R**(2/3)) * (Sf**-0.5)) / n Tc = (Lf / V) / (3600sec/hr) Where: R =Hydraulic radius Aq = Flow area, sq.ft. Wp = Wetted perimeter, ft V =Velocity, ft/sec Sf = Slope, ft/ft n = Mannings n Tc = Time of concentration, hrs Lf = Flow length, ft S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 I~~._ 1 I,..1 \) Type.... Tc Calcs ~ _ / Name.... SUBAREA 3 File.... G:\713060\Hydro\713060 Post.ppw P~. ;~ 4.07 ........................................................................ ......................................................................... TIME OF CONCENTRATION CALCULATOR ........................................................................ ........................................................................ Segment #1: Tc: User Defined Segment #1 Time: .0067 hrs ------------------------------------------------------------------------ Segment #2: Tc: User Defined ~1 l_ J _.J r~ ~~ -----------------------------------------Segment-#2-Time-----0300-hrs Segment #3: Tc: User Defined Segment #3 Time: .6000 hrs ----------------------------------------------------------------------- Segment #9: Tc: TR-55 Channel Flow Area .0870 sq.ft Wetted Perimeter 1.05 ft Hydraulic Radius .08 ft Slope .010000 ft/ft Mannings n .0120 Hydraulic Length 290.00 ft Avg.Velocity 2.36 ft/sec Segment #4 Time: .0341 hrs ----------------------------------------------------------------------- Segment #5: Tc: TR-55 Channel Flow Area .7850 sq.ft Wetted Perimeter 3.14 ft Hydraulic Radius .25 ft Slope .010000 ft/ft Mannings n .0120 Hydraulic Length 9.00 ft J ~0 ,~ ~~ 'IiJ Avg.Velocity 4.93 ft/sec Segment #5 Time: .0005 hrs ------------------------------------------------------------------------ S/N; Bentley PondPack (10.00.027.00) Bentley_Systems, Inc. ! 9:25 AM 12/4/2008 Type.... Tc Calcs ~~~ Name.... SUBAREA 3 File.... G:\713060\Hydro\713060_Post.ppw (~.. P~ti, ~~ 4 .0 8 Segment #6: Tc: TR-55 Channel Flow Area 1.2300 sq.ft Wetted Perimeter 3.93 ft Hydraulic Radius .31 ft Slope .010000 ft/ft Mannings n .0120 Hydraulic Length 40.00 ft Avg.Velocity 5.72 ft/sec Segment #6 Time: .0019 hrs ------------------------------------------------------------------------ Total Tc: .6733 hrs ------------------------- ------------------------- I '~ S/N: _ _ Bentley Systems,. Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 ~, _.~~__~.___~_._.___..---_--__._...__._.._._._.___-__.,~_.____._.__....___._._..._.__~_._.._~_._.__._,..___...__ _.__.__._._.__.__.__________.___.a._....__.__,-.-_,__.._._...u_.. ~ J -_i I L ~ Type.... Tc Calcs `~_~ ~~ ,s 4.09 Name.... SUBAREA 3 II,_l File.... G:\713060\Hydro\713060_Post.ppw I_ Tc Equations used... ___= User Defined ______________________________________________________ Tc = Value entered by user '~ l Where: Tc = Time of concentration ---= SCS Channel Flow =---=--------------------------------------------- (~ R = Aq / Wp ' V = (1.49 * (R**(2/3)) * (Sf**-0.5)) / n (( Tc = (Lf / V) / (3600sec/hr) I Where: R =Hydraulic radius ~ Aq = Flow area, sq.ft. Wp = Wetted perimeter, ft ~ V =Velocity, ft/sec Sf = Slope, ft/ft I- n = Mannings n Tc = Time of concentration, hrs ~"~ Lf = Flow length, ft I ~l `l J r~ ~J ~ g/N; _ Bentley Systems, Lnc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2,008 J _...... _.. __ .~_ _,_..._..__..__.. _.. _ ___._..._... ._...-.~_____...___._..._.__._ Type.... Pond E-V-Q Table Name.... DET POND File.... G:\713060\Hydro\713060_Post.ppw L~ P.~,_ 15.01 LEVEL POOL ROUTING DATA HYG Dir = G:\713060\Hydro\ Inflow HYG file = pad.hyg - work DET POND IN Dev 2 Outflow HYG file = _ work pad.hyg - DET POND OUT Dev 2 Pond Node Data = DET POND Pond Volume Data = DET POND Pond Outlet Data = Det Pond Outlet No Infiltration INITIAL CONDITIONS ------ - ------------------ Starting WS Elev --------- = 133.00 ft Starting Volume = .000 ac- ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qou t= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage Area Infilt. Q Total 25/t + 0 ft cfs ac-ft acres cfs cfs cfs ---------------------- 133.00 .00 --------------- .000 --------- .0650 ------------ .00 ---------- .00 ---------- .00 133.10 .03 .007 .0677 .00 .03 3.24 133.20 .12 .014 .0705 .00 .12 6.68 133.30 .26 .021 .0734 .00 .26 10.31 133.40 .46 .028 .0763 .00 .46 14.12 133.50 .69 .036 .0793 .00 .69 18.12 133.60 .97 .044 .0823 .00 .97 22.31 133.70 1.28 .052 .0854 .00 1.28 26.68 133.80 1.61 .061 .0885 .00 1.61 31.22 133.90 1.98 .070 .0917 .00 1.98 35.95 134.00 2.35 .080 .0950 .00 2.35 40.84 134.10 2.72 .089 .0983 .00 2.72 45.89 134.20 3.10 .099 .1017 .00 3.10 51.12 134.30 3.49 .110 .1052 .00 3.49 56.51 134.40 3.86 .120 .1087 .00 3.86 62.05 134.50 4.20 .131 .1123 .00 4.20 67.74 134.60 4.34 .143 .1159 .00 4.34 73.41 134.70 4.47 .154 .1196 .00 4.47 79.23 134.80 4.61 .167 .1233 .00 4.61 85.26 134.90 4.77 .179 .1271 .00 4.77 91.47 _~ '--~ S / N Bentley PondPack (10.00.027.00) ri _l _~_._.,._.._ ____ .._..~~_.__ a.____... _.,_..__ __.._ ._.. __..__..._. __. _' Bentley Systems,.. Inc. 9:25 AM 12/4/2008 ~ Type.... Pond E-V-Q Table \^! A__, ~ 5.02 Name.... DET POND `-~ File.... G:\713060\Hydro\713060_Post.ppw ~,_ i LEVEL POOL ROUTING DATA HYG Dir = G:\713060\Hydro\ Inflow HYG file = pad.hyg - DET POND work IN Dev 2 Outflow HYG file = _ work pad.hyg - DET POND OUT Dev 2 Pond Node Data = DET POND Pond Volume Data = DET POND Pond Outlet Data = Det Pond Outlet No Infiltration INITIAL CONDITIONS ----- ---------------- ------------- Starting WS Elev = 133.00 ft Starting. Vo~.ume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs Elevation Outflow Storage Area Infilt. Q Total 2S/t + 0 ft cfs ac-ft acres cfs cfs cfs ---------------------- 135.00 4.92 ------------------------ .192 .1310 -------------------------------- .00 4.92 97.87 'r J S/N: Bentley PondPack (10.00.027.00) ~a J_...____ _ ..~- - - ~-- -__ 9:25 AM Bentley Systems, Inc. 12/4/2008 Type.... Pond Routing Summa Name.... DET POND OUT Taq: Dev 10 File.... G:\713060\Hydro\713060 Post.ppw Storm... TypeIII 24hr Tag: Dev 10 LEVEL POOL ROUTING SUMMARY HYG Dir = G:\713060\Hydro\ Inflow HYG file = work pad.hyq - DET POND Outflow HYG file = work pad.hyg - DET POND Pond Node Data = DET POND Pond Volume Data = DET POND Pond Outlet Data = Det Pond Outlet No Infiltration INITIAL CONDITIONS ---------------------------------- Starting WS Elev = 133.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .OO cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs INFLOW/OUTFLOW HYDROGRTIPH SUMMARY IN Dev 10 OUT Dev 10 Peak Inflow = 2.39 cfs at 12.1000 hrs Peak Outflow = 1.38 cfs at 12.2000 hrs --- ---- ---- Peak --------------- Elevation = ----------- 133.73 -- --- ----------- ft Peak ---- ---- Storage = --------------- --------------- .055 ----------- ----------- ac-ft ----------------------- ----------------------- MASS BALANCE (ac-ft) -------------------------- + Initial Vol = .000 + HYG Vol IN = .221 - Infiltration = .000 - HYG Vol OUT = .221 - Retained Vol = .001 Unrouted Vol = -.000 ac-ft (.005 of Inflow Volume) J r~ i_..~ '-~ S/N: Bentley PondPack (10.00.027.00) r -i l_ _ _ _ _ _ _ _ _ _ ._ ._ . _ ____ _ ._._ ___ .__. __,_ . __ ___ _. ,__~ 9:25 AM ~\l Ft__,~ 5.03 Event: 10 yr Bentley Systems, Inc. 12/4/2008 Type.... Pond Routing Summal~ Name.... DET POND OUT Tag: Dev 50 File.... G:\713060\Hydro\713060_Post.ppw Storm... TypeIII 24hr Tag: Dev 50 LEVEL POOL ROUTING SUMMARY HYG Dir = G:\713060\Hydro\ Inflow HYG file = work pad.hyg - DET POND Outflow HYG file = work pad.hyg - DET POND Pond Node Data = DET POND Pond Volume Data = DET POND Pond Outlet Data = Det Pond Outlet No Infiltration INITIAL CONDITIONS ---------------------------------- Starting WS Elev = 133.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs INFLOW/OUTFLOW HYDROGRAPH SUMMARY IN Dev 50 OUT Dev 50 Peak Inflow = 3.21 cfs at 12.1000 hrs Peak Outflow = 1.93 cfs at 12.2000 hrs - --- ---- ---- ----- Peak -------------- Elevation ----------- = 133.89 -- ------ -- - ft Peak ---- ---- Storage = -------------- -------------- .069 ------------ ------------ ac-ft ----------------------- ----------------------- MASS BALANCE (ac-ft) -------------------------- + Initial Vol = .000 + HYG Vol IN = .301 - Infiltration = .000 - HYG Vol OUT = .300 - Retained Vol = .001 Unrouted Vol = -.000 ac-ft (.004$ of Inflow Volume) r~ I I l r-l ,.~1 S/N: Bentley PondPack (10.00.027.00) 9:25 AM F~, ~ 5.04 Event: 50 yr Bentley Systems, Inc. 12/4/2008 --~II 1~.~._ _ __. __ _- _, Type.... Pond Routing Summai\_ / Name.... DET POND OUT Tag: Dev100 File.... G:\713060\Hydro\713060_Post.ppw Storm... TypeIII 24hr Tag: Dev100 P~~ 5.05 Event: 100 yr LEVEL POOL ROUTING SUMMARY HYG Dir = G:\713060\Hydro\ Inflow HYG file = work_pad.hyq - DET POND Outflow HYG file = work pad.hyg - DET POND Pond Node Data = DET POND Pond Volume Data = DET POND Pond Outlet Data = Det Pond Outlet No Infiltration INITIAL CONDITIONS ---------------------------------- Starting WS Elev = 133.00 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs INFLOW/OUTFLOW HYDROGRAPH SUMMARY IN Dev100 OUT Dev100 Peak Inflow = 3.43 cfs at 12.1000 hrs Peak Outflow = 2.07 cfs at 12.2000 hrs --------------------- ----- Peak -------------- Elevation = ---------- 133.93 --- ft Peak ----- ----- Storage = -------------- -------------- .073 ---------- ---------- ac-ft ------------------------ ------------------------ MASS BALANCE (ac-ft) + Initial Vol = + HYG Vol IN = - Infiltration = - HYG Vol OUT = - Retained Vol = Unrouted Vol = .000 .322 .000 .322 .001 -.000 ac-ft (.004$ of Inflow Volume) ;~ S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 11 .I_._____.._.__...__..__~.___.._.._...__,______.__..__._.._._._ ~,._--.__.._.,__,.. ... ...__._. .__.._.____.__...-~.,____..._._..._._ _._... _..._..._~._-_.___~_.__._.__.. ~_~ ~. _ 1 Type.... Pond Routing Summa Name.... GR STORAGE OUT Tag: Dev 10 File.... G:\713060\Hydro\713060_Post.ppw Storm... TypeIII 24hr Tag: Dev 10 LEVEL POOL ROUTING SUMMARY HYG Dir = G:\713060\Hydro\ Inflow HYG file = work_pad.hyg - GR STORAGE IN Dev 10 Outflow HYG file = work pad.hyg - GR STORAGE OUT Dev 10 Pond Node Data = GR STORAGE Pond Volume Data = GR STORAGE Pond Outlet Data = Gr Stor Outlet Infiltration = .1700 in/hr INITIAL CONDITIONS ---------------------------------- Starting WS Elev = 134.65 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs INFLOW/OUTFLOW HYDROGRAPH SUMMARY Peak Inflow = 3.04 cfs at 12.5000 hrs Peak Outflow = .96 cfs at 13.2000 hrs Peak Infiltration = - - ---- .08 -- - --- cfs at 13.2500 hrs ----------------------- ----- Peak --- --- -- - Elevation = - - - 134.88 - ft Peak ---- ---- Storage = ---------------- ---------------- .175 --------- --------- ac-ft ------------------------ ------------------------ MASS BALANCE (ac-ft) -------------------------- + Initial Vol = .000 + HYG Vol IN = .451 - Infiltration = .030 - HYG Vol OUT = .420 - Retained Vol = .001 Unrouted Vol = -.000 ac-ft (.000$ of Inflow Volume) I'J S /.N . Bentley PondPack (10.00.027.00) l ._.~; _ _ __ _ _ __ _ _ _ _ .__ _ __ _ a __ .__ _ __ _._ 9:25 AM 1 ^\I P.___,! 5.0 6 Event: 10 yr Bentley Systems., Inc. 12/4/2008 ~ Type.... Pond Routing Summa Name.... GR STORAGE OUT Tag: Dev 50 File.... G:\713060\Hydro\713060 Post.ppw -~ Storm... TypeIII 24hr Tag: Dev 50 - LEVEL POOL ROUTING SUMMARY II'~ it HYG Dir = G:\713060\Hydro\ Inflow HYG file = work pad.hyg - GR STORAGE IN Dev 50 Outflow HYG file = work pad.hyq - GR STORAGE OUT Dev 50 Pond Node Data = GR STORAGE Pond Volume Data = GR STORAGE Pond Outlet Data = Gr Stor Outlet Infiltration = .1700 in/hr INITIAL CONDITIONS ---------------------------------- Starting WS Elev = 134.65 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs INFLOW/OUTFLOW HYDROGRAPH SUMMARY Peak Inflow = 4.91 cfs at 12.5000 hrs Peak Outflow = 1.82 cfs at 13.1000 hrs Peak - Infiltration = --------------- .20 --------- cfs at 13.1000 hrs ------------------------ ---- Peak Elevation = 135.00 ft Peak Storage = .269 ac-ft MASS BALANCE (ac-ft) -------------------------- + Initial Vol = .000 + HYG Vol IN = .722 - Infiltration = .055 - HYG Vol OUT = .666 - Retained Vol = .001 Unrouted Vol = -.000 ac-ft (.000% of Inflow Volume) P ~%-\15.0 7 Event: 50 yr S/N: Bentley Systems, Inc. Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 i ^1 Type.... Pond Routing Summa( _J Name.... GR STORAGE OUT Tag: Dev100 File.... G:\713060\Hydro\713060_Post.ppw Storm... TypeIII 24hr Tag: Dev100 LEVEL POOL ROUTING SUMMARY l„ HYG Dir = G:\713060\Hydro\ Inflow HYG file = work pad.hyg - GR STORAGE IN Dev100 Outflow HYG file = work pad.hyg - GR STORAGE OUT Dev100 Pond Node Data = GR STORAGE Pond Volume Data = GR STORAGE Pond Outlet Data = Gr Stor Outlet Infiltration = .1700 in/hr INITIAL CONDITIONS ---------------------------------- Starting WS Elev = 134.65 ft Starting Volume = .000 ac-ft Starting Outflow = .00 cfs Starting Infiltr. _ .00 cfs Starting Total Qout= .00 cfs Time Increment = .0500 hrs INFLOW/OUTFLOW HYDROGRAPH SUMMARY Peak Inflow = 5.42 cfs at 12.5000 hrs Peak Outflow = 2.07 cfs at 13.0500 hrs Peak Infiltration = ------------- .23 --------- cfs at 13.1000 hrs ------------------------ ---- Peak --- Elevation = 135.03 ft Peak Storage = .294 ac-ft / \ P~, 5.08 Event: 100 yr MASS BALANCE (ac-ft) + Initial Vol = .000 + HYG Vol IN = .798 - Infiltration = .063 - HYG Vol OUT = .734 - Retained Vol = .001 Unrouted Vol = -.000 ac-ft (.001 of Inflow Volume) II ~J '- S/N; _ _ _ _ Bentley Systems, Inc. 1 Bentley PondPack (10.00.027.00) 9:25 AM 12/4/2008 I____.___._..__ _....._ __ __ ,__ .. __ ~__ _~ ~ ..~__._~ _. _ _..__,__ .. __._ :_~ ~ I J Appendix A (_._ l L.1 Index of Starting Page Numbers for ID Names i1 5.07, 5.08 ----- H ----- Hampshire, MA... 3.01 ----- S ----- SUBAREA 1..., 4.01 SUBAREA 2... 4.03 SUBAREA 3... 4.07 ----- W ----- Watershed... 1.01, 2.01, 2.02, 2.03, 2.04, 2.05 L.. '-' S/N: Bentley PondPack (10.00.027.00) 9:25 AM i ~`~ Bentley Systems, Inc._ 12/4/2008 J ~_~ ~__ ~ ATTACHMENT C: SOILS INFORMATION FOR SITE `'~_~ S ' lap-Hampshire County, Massachusetts, Central Par (Synthetic Turt Field Smith College) Il J ~~ ~~ ~_J l liII ~._._ l.__.___ __ __... _ ,J N Meters A 0 35 " 70 140 210 Feet 0 150 300 600 900 ~~ Natural Resources Web Soil Survey 2.0 11/5/2008 fr Conservation Service National Cooperative Soil Survey Page 1 of 3 (~ ~~ f~ ~~ m c _ U .-. _N w rn .. m U .C J N m ~ w LL 1 ~~ ~-~ 3 U E' O U r~ L N I JII w n. c T v I flcc• G ~~ N N O O c fl. U ~ ° f6 ° ro ° ~ ' c ~ ° ° > U : m v ~ U a~ ~ -~ .O O O ~ Z m O N N°c E amt UJ ~ 'C tq O) ~ O B -Y N =O" > d V j O U t ~ •~ m Z (0 m ~ m E U z ~ v ~ "' .Q O : 0 N~ V , O O ~ ~ m O w~~ L Q O_ N N C 7 Z ~ N 'O L O~ `o.a>io UNZ o ~ ~ ~ a 3Lmc N ~ ~ ° ° m Nor = ~ c ~ ° ° °Qv O 3 v ~' N ° N a~ ~ ~ U -~ o ~ m "° fl. a~ Z N m ° ' 0 aN N 3 o ~ ~ co a E ?• m a~ a~ ~ ~~ ~ ~ a i ~ t c ' r O N t w .O O. ` ~ m p (A O Q ° ~ J N N S v) ~ N S O O N ~, °- >~ w Z ~ ~ ~ N rn O ° ~ ° m ' Z C~ N m N~ T ..0. N N O O) .O-. m d .m. m ~ O m N C O -p >~ 7 N N ~ ~ m = ~ ~ ~ Q ~ ~p O 'O N ° n .c NNam ~cn°~ ~a y ~ ~ o°'-N-o 'c ~ rn- a~ °'o c o~` Z Q T m s ~ ~c c ~ ~ E u~v a~ in i a ~ o'fl ~m m~ ~ 0 7 N r ' C Z . N E N E ~ . O > `o E 0 v°~ ~ U FL--_°. in d tq O IL- v ~ o N u1 ~ Q C N 0 °' o ~ U t m ~ c m m m ~ c ~ ~ o. io i a ~ ~ c ` ° E y .m.. ~ p 2 ` ° O 4' o R' Z, v) a~ ~ ?~ o m ~ y w m ~ ~ w • ~ N ~ a; m m U U L d > ~ O c > L t7 U L O w _ ~ ._ U '~ > N U > O _ U m L' ~~ ~ ~ ^ m ~ U ~ L_ O J d l0 m Q m {~ o , LL a A L+ w a ~ ~ W 7 : ~ t r 1. a ~ V IK ~ ~ ~ ~ ' ~ N ~ L A k ~ ': .:. Q a ~ F- W J a -- a a o w G fp V) ~ N .~,, . N .. N ~ m a V 5 n r a o ^ 'a > o O m m c a v°i >. m ~ c m a ~ LL O , v i L U T m N N ''-O C O O T N > m 4 m > m 'O m ~ ~ ~ m N U C N N N Y O C m D N UI N Y C y ~ O Q C ~ Q fn m m U U (:~ f:J J J Gr rL rL 0. 2' In fn V1 fn ~ !n (n (n d C ~ V, ---I ~ _.__i a ~ ® >C * }~ ~- -~" -~ ~t. OO OO `l + .. III t7 ,~, '0, INf ~.7 ~ Q a0 M O .~ O O N N rn t- m d T a~ Z o~ N 'O ~N N Z > ~ ' ~ m 'o a ~o ~° U a~ O (6 Z d v aNi ~ V N 7 ~ O C y ++ R L 7 N ZV C' Jb '~:~ r -~ ~~ II ~ Soil Map-Hampshire County, Massachusetts, Cer~~~al Part ~1 Synthetic Turt Field Smith College [~~ Map Unit Legend '~_ l I i_~ ~J Hampshire County, Massachusetts, Central Part (MA609) :.Map Uriit Symbol Map UnitName Acres in AOI Percent of AOI 1 Water 0.8 3.0% 30A Raynham silt loam, 0 to 3 14.0 53.2% percent slopes 220C Boxford silt loam, 8 to 15 6.6 25.3% percent slopes 741A Amostown-Windsor silty 4.8 18.5% substratum-Urban land complex, 0 to 3 percent slopes ~~ Totals for Area of Interest (AOI) L.J l_J ~J ~1 -~ ~~ ~~ J ~] L J ,1 26.2 100.0% `~'~ Natural Resources Web Soil Survey 2.0 11/5/2008. 'r Conservation Service National Cooperative Soil Survey Page 3 of 3 1 _I _~___. _ ._. _. _ .~ _ _ _ ---.._ _ .__. _..._ _ . ...,_._ _. ___._ .......... ...__. __. - ~oii ~~~ir~~~ ~ shire County, Massach~..~tts, Central Part ~ 1 "1 Ito tha tent iit ~_ InOh~'+~ eaH. ~ly ~~,-+1 ~ue aritf ._..~R pr '; ~lowt~r '~ ~~na of im, ar 3 to __,ery In me rp Irer the Im ---Muck f °~ B solum is 20 to 40 inches thick. Reaction ranges very strongly acid to slightly acid in unlimed areas. e Ap horizon has hue of 10YR or 2.5Y, value of 3 to id chroma of 2 to 4. e B horizon has hue of 10YR to 5Y and value and ma of 3 to 6. Low-chroma mottles are at a depth of than 24 inches. ie IIC horizon has hue of 10YR to 5Y, value of 4 to ~d chroma of 1 to 4. It ranges mainly from loamy fine I to sand. Thin strata of sandy loam, silt loam, or el are in some pedons. ham series The Raynham series consists of deep, poorly drained ills on old lakebeds. The soils formed in ~ciolacustrine deposits. Slopes range from 0 to 3 r,o, ...,.... Raynham soils are similar to Belgrade soils and in Many places are near Boxford soils. Raynham soils have rayer colors than those soils and have less clay than oxford soils. Typical pedon of Raynham silt loam, 0 to 3 percent slopes, in a cultivated field 3,200 feet northwest of the center of the village of North Amherst, in the town of Amherst: Ap-0 to 10 inches; very dark brown (10YR 2/2) silt loam; moderate fine and medium granular structure; friable; slightly acid; abrupt smooth boundary. B21-10 to 16 inches; dark brown (10YR 4/3) silt loam; few fine distinct strong brown (7.5YR 5/6) and grayish brown (10YR 5/2) mottles; weak coarse subangular blocky structure; friable; strongly acid; clear smooth boundary. B22g-16 to 30 inches; grayish brown (2.5Y 5/2) very fine sandy loam; few to common fine and medium faint light olive brown (2.5Y 5/4) mottles and few fine distinct yellowish brown (10YR 5/4) mottles; weak medium and coarse subangular blocky structure; friable; strongly acid; abrupt smooth boundary. Cig-30 to 34 inches; grayish brown (2.5Y 5/2) silt loam; many medium prominent yellowish brown (10YR 5/4) mottles; massive; friable; medium acid; clear smooth boundary. C2g-34 to 37 inches; grayish brown (2.5Y 5/2) very fine sandy loam; few medium prominent brown (7.5YR 5/4) mottles; massive; friable; medium acid; clear smooth boundary. Cig-37 to 60 inches; gray (5Y 5/1) stratified loamy fine sand, silt, and fine sandy loam; few medium prominent strong brown (7.5YR 5/6) mottles and few medium distinct light olive brown (2.5Y 5/4) mottles; massive; friable; medium acid. The solum is 18 to 36 inches thick. Reaction in unlimed areas ranges from strongly acid to neutral in the solum and from medium acid to neutral in the substratum. The Ap horizon has hue of 10YR or 2.5Y, value of 4, and chroma of 1 to 3. It is silt loam or very fine say loam. The B horizon has hue of 10YR to 5Y, value of 4 tr and chroma of 1 to 4. It is silt loam or very fine sandy loam. The C horizon has hue of 2.5Y or 5Y, value of 4 to and chroma of 1 or 2. It is stratified silt, silt loam, ver fine sandy loam, loamy fine sand, and very fine sand. Ridgebury series The Ridgebury series consists of deep, poorly draii+ and somewhat poorly drained soils on glaciated upla The soils formed in glacial till. Slopes range from 0 t~ percent. Ridgebury soils are similar to Whitman soils and in many places are near Woodbridge and Scituate soils Ridgebury soils have a thinner, lighter colored surfac,~ layer than Whitman soils and are grayer in the upper of the subsoil than Woodbridge or Scituate soils. Typical pedon of Ridgebury fine sandy loam, in a wooded area of Ridgebury very stony fine sandy loam to 8 percent slopes, 150 feet north of Crooked Ledg; Road and 3,200 feet east of its junction with Delisle Road, in the town of Southampton: 01-4 inches to 1 inch; litter of leaves and twigs. 02-1 inch to 0; reddish black (2.5YR 2/1) well decomposed and partially decomposed leaves ~, twigs. Al-0 to 2 inches; very dark gray (10YR 3/1) fine s loam; weak medium granular structure; very friar many fine to coarse roots; 15 percent coarse fragments; very strongly acid; clear smooth boundary. B21-2 to 7 inches; grayish brown (10YR 5/2) fine sandy loam; few fine faint yellowish brown (10Y~ 5/4) mottles; weak fine and medium subangular blocky structure; very friable; many fine to coanl roots; 15 percent coarse fragments; very stron<; acid; abrupt smooth boundary. B22g-7 to 15 inches; gray (10YR 5/1) sandy loam common medium distinct light yellowish brawn 6/4) mottles; weak medium and coarse suban~ blocky structure; friable; many fine to coarse rcj 15 percent coarse fragments; strongly acid; ab~ smooth boundary. Cx-15 to 60 inches; olive (5Y 5/3) fine sandy loan many medium prominent reddish yellow (7.5YF' yellowish red (5YR 5/6), and grayish brown (2. 5/2) mottles; massive; firm; 15 percent coarse4 fragments; strongly acid. Depth to the fragipan ranges from 10 to 25 inch The content of coarse fragments ranges from 5 to. J 170 CI O O s. L 0 U O Iw C~ r-1 L_J N a..~ d L U 0 -U- b N rl N N m N O •~ U V] C ~ -- •~ ~ C .~.~ rn O C O •.~ N L y 1~ W U O ~ a -- ~ -- rn a~ c b L i m o x A a v 0 y A A c O C O .C A a a~ 4 .C y C O _~. C O m s. 7 _ O l~ ~1 Soil survey v v ~ h0 •'~ --------~----- tV m y ~° E - - -------- N ~ tV o ~ - ----- A •.+ x --------- m m -- -- ------ 71 y L 'UO ~ ---- -- --- N a~ L '00 ~ --- m m m •~ x ----- - ~ ~ d ~ -------~- i t .m -~-- i +' m d O ~---- I 1 I 1 ~ O „a . -- ---- ---- -- -- - d y~ m L y 'd O ~ - - 1 1 1 1 O a --- -- -- -- - N .N m L Gl •p O f ---------- I 1 I I O a ----- - N i~ m L N •0 O ~ ------ I I 1 1 O a --1 -_-__- I 1 I 1 1 3 O a ---------- ~ 1 1 ~ __ -_-_-_ ~ N O t N ,D O E --------- N N m N .~ ____ __ __ _ N ~ m i. y b p ~ --------- 1 1 1 ,d x --- _ __ ____ 1 I 1 1 ,C m •r+ ~ ----- I 1 I L ---5 -- 1 1 1 1 .C m •ri x -- I I 1 A ---~ -------- I 1 1 1 A e0 'rl x ------------ 1 I 1 13 -----=-- ~" m S.. y .p O ~ ----------- 1 1 1 3 ____ d m L N .p p E _ --- 1 I I ; __i -___ I I I .C pp ..1 x __-___-_ 1 'O 1 i i i 1 1 1 I ---- ---- 1 i ---- ------ 1 i -- ---- 1 i -------- - i 1 --- ------- ~ 1 - ---- --- 1 1 1 ~ m -- -- 0 ° ° N O I ~ ° ° O O ~ ~O ~O ~O ~ O n n ------ -- -- ---- ----- -- -- ---- --- -- -- -- a - ---- -------- -- ---- ------ ~ ---- --- L I- 0. ~ m f ~ 1 1 I ~ ~ ~ 1 j > > > > 1 1 N > A .D I 1 0 O O O N W N I z x Z' ____ -___ ________________ Z -_-_-_ _---_-_-_ -_ ---- __ ------- _y____ y -_- __-_ - .-__-___- --- ---_ - ------------ ~ _ ---- y C ~ C C C '0 ~ d N N N 1 1 1- L Z 1 d t I 1 m U V I d I d G o. c. c. I a. a m a d d d Q1 d d w d ---------------- ----- 6 ~- a' .. __ -- -- -_ -_ __ _ _ __ ---- ~- -------- ------------ - If1 --- _----__-. .. -- ~. . -__--.. . -.. ~- - O O U1 L[1 O /,.~ N N O M ~ 1 N 1 ~ I ~ 1 1 .O' ~O o ' 1 Ifs ~p ~o ~ ~ ° ° n n I ~' tl~ • n n ,.. o m d ¢ 1 1 1 1 1 p 1 1 ! 1 ~ ~ I I > ~ ~ 1 1 I I 1 I I O Z I I 1 1 Z z ____ ____________... __ ________ _ __ __ __ _ _-_--..... _ ___ _____ ... ~-__-____ ________ __ 1 I _ __ __ _ .___ ____ ____ _ I I 1 1 1 1 I I 1 1 I 4 I I 1 I ~ w j 1 ~'"' W I I i i I °' 1 1 m ' „ , .~, L ~ c. m m ______ ______~... ;.n ___________ '~~ _---__ _..-------------------- _________ -------~ I ____' i 1 1 :c. 1 1 1 I I I 1 `. 1 I 1 1 1 I I 1 ~ ~ ~ 1 1 1 1 ~ ~'`,ii 1 1 1 1 1 1 I C 1 1 C 1 I d 1 1 1 I 1 1 I d I 1 1 O 7 I 1 F ~ 1 1 1 1 ~ ~. I y N O' dJ -~ ~ni 41 O C v N C C C O C p C O z U L W C C O O {~. 2 ~ ! z ~; ~~~~~' ~~:. ~:.~. ~ Z z Z Z Z W z --- _y n,k~dyy -- ---------- : .'~-': ~ m U U U U m ~ m U U m U a Q T U C N 7 O' N Cu i s. •o a~ C .~ C O v 1 1 N w a E d w w a la1 F 6 3 0 z 6 a O N 1 1 G] a m d F 1 U O •rl L tC 'd O >. r-1 x -_ e b C m ~ O E E m >, c rn ~ a •~ m `O E ---- - ------------ ------ -- -- -- -- -- -- -- -- -- -- -- - I I 1 . I -------- ~ 1 I I 1 I 1 I I i I I I 1 1 I 1 1 1 1 1 1 1 i I 1 1 j ^A Q 1 I 1 1 1 V 1 I 1 j ^ 1 N I 1 1 O O a~ +~ 1 1 d I AA U I 1 7 I L •• L d ~ ~ w w w a l L ~ y " .. ~k U 1 w i 1 1 C .. 1 Y N 1 i 1 O j E W o~ C ~ . I d o~ I A ^vv I I C 1 1 c 0 m ~-+ x i~ a i E m 1 A m I m o o x o ~ ti m~ mm o s vnn maw t o ° ~ w ~ , m % i~ o m i n i o z o . 0 C 1 b 1 a x ^.l u L L ,,a " ~ Z •c 1 m m 1= a .. x m a ..~i .. ~ i o ~ i >, I m ^ m .~ d y x t o. I .,~ U * o * v o m to .' ~'1 * v o d •.~ . m m .o D o w * m x c. • .~ d o ao- w t o w *~ s xm mm aw ~x moa z Kf mz ooz mwww •pw v x w n. a a z z w w _f~. _. - _ _ __ _w- _ _ ATTACHMENT D: OPERATIONS AND MAINTENANCE PLAN i _..~ ~.~ ~~ _, Smith College Synthetic Turf Athletic Field And Site Improvements Project Operations & Maintenance Plan PART 1- STORMWATER MANAGEMENT SYSTEM DESCRIPTION 1A. OWNER: Smith College Facilities Management 126 West Street Northampton, MA 01063 1B. OPERATION: Stormwater carries pollutants and by law must be treated before discharge to wetlands and water bodies. The site plans which accompany these instructions show the components of the treatment system, direction of flow and nearby resource areas. _ A closed pipe system is being proposed to collect water from the synthetic ~ ~ turf multipurpose field, and parking area and to treat Stormwater from -~ the parking area. A vegetated detention basin will be utilized to pretreat the impervious parking area. After being conveyed through the closed l pipe drainage system, the flow will then be discharged into the Mill River, ~_I via an existing discharge outlet. The vegetated detention basin will serve the purpose of settling out sediments in runoff prior to discharge to the Mill River. In several locations on the site, Stormwater will continue to flow by sheet flow or conveyed through a sub-drain system and discharged to the Mill Rive via existing discharge outlets. 1C. NPDES: ~~ Because total area proposed to be disturbed is more than one acre, the project must conform to a Stormwater pollution prevention plan that shall be prepared in conformance with the national pollutant discharge j ~ elimination system general permit for Stormwater discharge from ~J construction activities (federal register part 2, February 17, 1998). i_ 1 ~_ ~l PART 2 -RESPONSIBILITY FOR OPERATION AND MAINTENANCE 2A. PARTY RESPONSIBLE DURING CONSTRUCTION: General Contractor - To Be Determined. 2B. PARTY RESPONSIBLE FOR POST-CONSTRUCTION: Smith College Facilities Management _; 126 West Street Northampton, MA 01063 PART 3 -INSPECTION AND MAINTENANCE SCHEDULE 3A. CONSTRUCTION SCHEDULE: As required by the Town of Northampton Conservation Commission in an Order of Conditions, to be issued. 3B. POST-CONSTRUCTION SCHEDULE: ~~ The Northampton Conservation Commission issues an order of conditions (a permit with specific conditions which must be followed during and upon completion of the work) allowing the work to be performed. Upon ~--~ completion, the owner must apply for and receive a certificate of _ compliance. This certificate(s) and order of conditions is issued under the 1 Massachusetts wetlands protection act. The order and certificate should be written to allow for routine maintenance during the construction and post-construction phases. A continuing condition in the certificate should ensure that maintenance can be performed without triggering further filings. 3B.1 ROUTINE SCHEDULE: The property's stormwater handling facilities must be inspected on a regular basis in order to comply with the project's wetlands permit. Routine inspections must be made during the months of April and October of each calendar year as follows: Inspect all catch basins (CB) and trench drains at locations shown on site l plans. Look for settling around structure and repair as required. Look at ~-~ level of sand,- silt in bottom. Have bottom cleaned if outlet pipe appears ~.._ 2 ;~ blocked. Verify that elbow (oil trap) on final CB in system is securely in place. Clean all leaves, trash, and pine needles out of CB grate. Look for signs of erosion at edges of pavement. Severe erosion may be caused by pipe blockage and resulting overflows out of catch basins. Where surface erosion is evident, remove drain manhole covers and CB grates in area and look for blockages. Segmental Block Retaining Walls Look for erosion at top and bottom of all retaining walls. Repair as required. L~ ~~ J r_1 _J __ i _ ~. --- .__._. ___ Vegetation Inspect for diseased/dying trees, shrubs, ground cover, grass. Remove/repair as required. Existing Flared end sections Inspect stone slope protection. Cut vegetation growing in stones and remove all debris. 3B.2 NON-ROUTINE SCHEDULE: Vegetation Inspect after each significant rainfall (1" or more) for first 6-months after construction to ensure surface vegetation is healthy, discharge devices are not blocked and banks are not eroding. Check all components after each major storm (more than 2" rainfall in 24 hours). Clean/repair as required. Catch basins Have all catch basins, trench drains and area drains cleaned out completely twice annually during April and October by outside contractor, if required. 3B.3 EMERGENCIES: In the event of an emergency spill release or other unexpected contamination event, all contaminated runoff from pavement must be prevented from leaving the property by performing the following: 3 I~ / ,~ At discharge pipe to wetlands, place layers of sand bags to block the pipe end at the wetlands. The contractor must have ready at all times, filled sandbags (or equal) to accomplish containment throughout the construction activity. PART 4 -DOCUMENTATION Smith College's Facilities Management shall perform inspections in accordance with the "Stormwater Management System (SMS) Operation and Maintenance Plan" as described in this sheet. A written inspection record should document all areas of concern and identify names of inspectors and dates of inspection. Erosion control notes 1. Prior to large or intense rainfalUrunoff events, the contractor shall apply mulch to stabilize disturbed areas not stabilized by vegetation. 2. All drainage and erosion control construction shall be located as depicted on the plan and as required by the engineer in the field dependent on the actual progress and sequence of construction. 3. A silt fence shall be installed around all stockpiled material. I_~ 4. All disturbed areas are to be temporarily or permanently stabilized within 14 days of its disturbance. 5. All disturbed areas not under current construction shall be stabilized by rough grading to minimize slopes and mulched. Following final rl grading of any portion of the site; contractor shall loam, seed and I~I mulch within 48 hours. In areas where the seed and mulch do not take root, erosion control blankets shall be utilized. 6. Erosion control measures shall be monitored and maintained throughout construction and removed after project area and drainage courses are fully established and stable. 7. Siltation fence shall be installed according to manufacturer's recommendations. Where possible, silt fences shall be aligned parallel to slope contours with ends curved uphill. 8. Inspection and maintenance: inspect erosion and sediment control measures frequently. Pay careful attention to weather predictions. ~ Watch for predicted thaws or heavy rains. Before such events, check ~_I all control measures to be sure that structures will manage the potentially heavy and intense runoff and sediment. As early as is ~~J _. 4 r ~ ~ ~> ~~ -~ j practical install permanent vegetative controls such as loaming, J seeding, sodding, mulching and planting trees. ~ ~'I 9. Any slopes greater than 3:1 shall be matted with an erosion control ~.- 1 mat such as North American green or approved equal. !~ 10. In loose soil conditions, the use of staple or stake lengths greater than 6" (15cm) may be necessary to properly secure the blankets. 11. If not otherwise noted on plans use north American green SCI50 on slopes less than 2H:1V and c125 matting on slopes greater than 2H:1V and less than 1.5H:1V. G:\713060NOI\713060 0&M Plan.doc 5