Loading...
Site Investigation USPS PART I town 6 Riverside Drive •Suite 101 •Andover. MA 01810-1121 • (508)682-1980 • Fax(508)975-2065 November 7, 1995 Mayor Mary Ford City of Northampton 210 Main Street Northampton, Massachusetts 01060 RE: Public Involvement - Report Submittal U.S. Postal Service Main Office - Northampton, MA EMCON Project No. 89375029.000 REC NUN - 8 1995 IhIAYOR OF P!OR Ht _.__. Dear Mayor Ford: On behalf of the United States Postal Service, EMCON has prepared the following documents for the U.S. Postal Service Main Office located at 37 Bridge Street in Northampton, Massachusetts: • Supplemental Phase II Site Assessment - Adjacent Property • Phase III Remedial Action Plan • Phase IV Remedy Implementation Plan Pursuant to 310 CMR 40.1403(3)(e) of the Massachusetts Contingency Plan (MCP) (Public Involvement Activities),this letter serves as notification to the availability of the above-mentioned reports, which have been submitted to the Massachusetts Department of Environmental Protection (DEP). A brief summary of these documents is provided in the following paragraphs. Supplemental Phase 11 Site Assessment-Adjacent Property Based on the results of the investigative activities completed at the site, a release of petroleum (gasoline) to the groundwater has occurred. The source of the release was either spillage or leakage from a 4,000 gallon underground storage tank (UST), which was removed from the site in 1989. A separate phase layer on top of the groundwater exists within a limited area on the U.S. Postal Service property. A dissolved volatile organic compound (VOC) plume in groundwater has migrated approximately 180 feet off of the U.S. Postal Service property onto the adjacent Saint John of Cantius Church property. Based on the approximate extent of the contaminant plume, the dissolved VOCs are situated on the western portion of the Church property and extend north to south across the property at an approximate width of 45 feet. No separate phase product was detected in any of the wells on the Church property. Based on contaminant concentrations in groundwater in excess of applicable standards,further remedial response actions on both the U.S. Postal Service and Church property are required to achieve a level of No Significant Risk. Mayor Ford November 7, 1995 Page 2 Phase Ill - Remedial Action Plan The purpose of the Phase III is to meet the requirements set forth in the MCP (310 CMR 40.0850). Components of the Remedial Action Plan included the following: summaries of the previously completed activities at the site;identification of appropriate remedial action objectives and development of cleanup levels for groundwater and soil; descriptions of the methods and results of the groundwater modeling activities; identification and screening of remedial action technologies and process options that are reasonably likely to be feasible and achieve a level of No Significant Risk; and evaluation and selection of a remedial action alternative. The remedial action alternative selected as a result of the Phase III evaluation was: groundwater extraction at the source area and leading edge of the contaminant plume with vacuum enhancement at the source area and enhanced bioremediation. Phase IV- Remedy Implementation Plan The purpose of the Phase IV is to ensure that the information, plans, and reports related to the design, construction, and implementation of the selected remedial action alternative are sufficiently developed and documented to ensure that following implementation, the remedial action meets the design and performance specifications. Components of the Remedy Implementation Plan included the following: descriptions of the engineering design criteria, including design assumptions and calculations, system operating parameters, remedial action alternative description and implementation, and remedial waste management procedures; detailed construction plans and specifications;the operation,maintenance and\or monitoring plan;and health and safety procedures. A summary of the three major components of the selected remedial action alternative is discussed in the following subsections. Groundwater Extraction at the Source Area and Leading Edge of the Contaminant Plume Groundwater extraction at the source area and leading edge of the contaminant plume will achieve containment and recovery of the dissolved VOC contaminant plume and enhance the recovery of separate phase product. To achieve this objective, three groundwater extraction wells will be installed to remove contaminated groundwater. One of the wells will be located on the U.S. Postal Service property adjacent to the removed UST and within the separate phase product plume (RW-1, current short term measure [STM] well). Mother well (RW-3) will be located at the leading edge of the dissolved VOC plume (approximately 180 feet from the former UST and on the adjacent Church property). The third extraction well (RW-2) will be located at the approximate 30.11195.89375029.000\002.Rr Mayor Ford November 7, 1995 Page 3 midpoint of the dissolved VOC plume. Initially each of the wells will extract groundwater at an approximate rate of 2 gallons per minute (gpm). Groundwater will be pumped separately through in-line flow meters, flow regulating valves, and sampling ports. The flow will then be combined into one discharge pipe and pumped through a series of bag filters and two 500 pound granular activated carbon canisters linked in series. The majority of the effluent water will then be discharged to the on-site stormwater collection system. A component of the effluent discharge will be reinjected back into the aquifer (see discussion below - Enhanced Bioremediation). The effluent will be discharged in accordance with the provisions of an exclusion from a National Pollution Discharge Elimination System (NPDES) permit and 310 CMR 40.0040 Mana•ement Procedures for Remedial Wastewater and Remedial Additives Vacuum Enhancement at the Source Area Vacuum enhancement at the source area ll address s theuratid residual g sole contaminants in vadose zone, capillary fringe, and providing an oxygen source to increase biodegradation; 2) extracting volatil s fr from these zones; and 3) potentially increasing product recovery by applying a vacuum overcome capillary forces. Vacuum enhancement will consist of extracting vapors a 2 horsepower regenerative [ extraction well on the U.S. Postal Service property (RW-1) utilizing P blower. The recovered vapors will be treated through two regenerable granular activated carbon units linked in series. Initial operating parameters (based on the results of a pilot test), will be an extraction rate of approximately 90 cubic feet per minute (cfm) at a wellhead vacuum of 10 inches of water. Since point source remedial air emissions generated from the operation of the vacuum enhancement system will be less than 1 ton per year, the system will be operated and monitored in accordance with DEP Policy #WSC-94-150 Off-Gas Treatment of Point-Source Remedial Air Emissions and 310 CMR 7.03 (14) Groundwater/Soil Venthw Systems. Enhanced Bioremediation Enhanced bioremediation of groundwater includes the reinjection of amended water (i.e., oxygen, nutrients, and potentially bacterial mixtures) to enhance the biodegradation of hydrocarbons within the aquifer. The enhanced bioremediation activities will be implemented as Phase II of the remedial action alternative (scheduled for Spring of 1996). The reason for this phased approach is to evaluate the operation of the groundwater recovery system (i.e., pumping rates, zones of influence, etc.) to allow for optimal placement of the injection wells 30.11/95.89375029.000 002.1tr Mayor Ford November 7, 1995 Page 4 Based on the needed oxygen levels, hydrogen peroxide will be applied intermittently(to prevent degassing) as the oxygen source with ammonium chloride and potassium phosphate as the nutrient supply. The amended water will be reinjected via will injection wells located near to be added to both on-property and off-property will allow nutrients and oxygen oxygen to portions of the aquifer. The vacuum enhancement component will supply xyg the subsurface soils to promote increased biodegradation within this zone. The hydrogen peroxide and nutrients will be pumped into a portion of the effluent stream rates for the hydrogen peroxide and nutrients hue 0.3 gallons per cday.�tThe effluent discharge to groundwater will be performed in accordance with the provisions of 310 CMR 40.0040 Mama ement Procedures for Remedial Wastewater and Remedial Additives. These pertaining completed documents, may be obtained at the other Regional Office, documents 3rtaiwng Massachusetts. The telephone located at 436 Dwight Street, Suite 402, Springfield, number is (413) 784-1100 and the DEP site number is 1-0901. The U.S. Postal Service is committed to implementing the remediation activities U.S. at the site. Pursuant to 310 CMR 40.1403(3)(a) (Notification requirements), Postal Service will commence Phase IV activities on or about November 13, 1995. The construction activities are anticipated to be completed within 2 to 3 weeks of initiation. If you have questions or require further information, please contact Randy McDermott of the U.S. Postal Service at (413) 731-0229 or Jeffrey Hamel of EMCON at (508) 682-1980. Sincerely, EMCON Jeffrey A. Hamel Project Manager cc: Randy McDermott, U.S. Postal Service Ruth Gottlieb, U.S. Postal Service oard of Health Peter McErlain, Northampton 30.11195.89375029.000\002.Rr SOURCE: BASE MAP TAKEN FRO 1:25,000 USGS TOPOGRAPHIC QUADRANGLE EASTHAMPTON,MASS. 1964-PR. 1979 AND MT. HOLYOKE,MASS. 1964-PR. 1979 d QUADRANGLE LOCATION Emcon DATE" 0,/ DWN APP R D n REV __ ROISE PROJECT NO. 09375.26 0 SCALE 1 MILE FIGURE 1-1 UNITED STATES POSTAL SERVICE NORTHAMPTON, MASSACHUSETTS SITE LOCATION MAP 1.0 INTRODUCTION The United States Postal Service(U.S.Postal Service) Northampton Main Post Office is located at 37 Bridge Street in the City of Northampton,Massachusetts (Figure 1-1). Since the late 1970's, a 4,000 gallon gasoline underground storage tank (UST),which was used to refuel post office vehicles, existed at the facility. In June 1989, as part of an UST installation survey,a soil boring/monitoring well was installed approximately 25 feet south of the tank. During drilling,a maximum soil jar headspace measurement of 1,000 parts per million volume per volume (ppm.) was detected in the soil sample collected from the water table surface. Subsequently, the U.S. Postal Service performed a tank integrity test. On August 17, 1989, the U.S. Postal Service notified the Massachusetts Department of Environmental Protection (DEP) that the tank failed the tank tightness test. At that time, all remaining gasoline in the tank was evacuated. On November 9, 1989, the tank was excavated and removed from the site. A representative of the Northampton Fire Department was on-site during the excavation and reported a small hole on top of the tank. In a letter correspondence dated May 3, 1991, the DEP determined that the Northampton Post Office was a Location To Be Investigated (LTBI) and required the U.S. Postal Service to complete a Preliminary Assessment,Phase I Limited Site Investigation,and disposal site classification form. Between August and September 1991,on behalf of the U.S. Postal Service, Wehran Engineering Corporation completed the above mentioned requirements. The results of the investigation concluded that soil and groundwater immediately downgradient from the former gasoline UST had been impacted from a release of gasoline. A floating separate phase gasoline layer was detected in two monitoring wells installed south of the former UST. There was no separate phase gasoline detected in the furthest downgradient monitoring well (approximately 50 feet from the former UST). However, concentrations of three volatile organic compounds (benzene, toluene, and total xylenes) were detected in groundwater from this well at concentrations in excess of State source f water standards. Given the direction of groundwater flow (north to south), the release was determined to be the former gasoline UST. In a letter correspondence dated October 31, 1991, the DEP issued a Notice of Responsibility to the U.S. Postal Service due to the observance and reoccurrence of free- 1-1 3e2J95.09375 261Phasell by the site to health, safety, public welfare, and the environment; and provide c necessary to develop remedial response alternatives. The scope of work conducted to satisfy the project objectives consisted of following tasks: preparing a Phase II Scope of Work, site specific health and safety far and quality assurance/quality control (QA/QC) form; installing retractable probes for field screening; installing soil boring/monitoring groundwal characteristic testing; wells; performing 8 collecting groundwater and soil s agwl performing an elevation and locations samples for nt; and survey; Pre laboratory analysi Phase II report. preparing a risk assessment; and preparing This report presents the results of the Phase II Assessment conducted at relative to these assigned and established objectives. Procedures used during sit investigation tabulation of the field data, and an interpretation and s 8 thi are detailed in the body of this report. Included in ommaryportare the: Phase II scope of work, health and safe m the appendices to this report are the: Phase II chromatograms oof ty form, and QA/QC form (Appendix from the retractable A); field and monitoring well construction to groundwater field d probes (Appendix rem B); soil boring from the soil boring/monitoring � (APPendrx C);field screening chromatograms from (Appendix I? o we (Appendix D); aquifer characteristic testing sheets Profiles E); lobo t an MCP ytical results - groundwater samples (Appendix F); (A Method 2 risk assessment standard ) PPendix H). ard calculations 1-3 302/95'09375 26/Phasell phase gasoline at two on-site monitoring wells. The letter required the U.S. Postal Service to submit a proposal to implement a Short Term Measure (STM) to abate an imminent hazard caused by the free-phase gasoline. In January 1992, a STM proposal, consisting of an automatic product only recovery system,was submitted to the DEP. The DEP approved the proposed STM in a letter dated February 11, 1992. The STM operated at the facility from February 1992 to November 1994, at which time it was modified to incorporate enhanced product recovery by active depression of the water table surface via groundwater extraction. As of December 30, 1994, app1oately 165 gallons of gasoline has been recovered from groundwater at the site. Although variable, product thickness is generally decreasing in the two monitoring wells. The STM Modification was approved by the DEP on September 8,1994,constructed during November and December 1994, and initiated operation during the first week of January 1995. Quarterly STM evaluation reports have been prepared since the implementation of the STM and submitted to the DEP. The last quarterly evaluation report was submitted on January 26, 1995. osal site on January The DEP listed the Northampton Post Office as a confirmed disposal 1992. A Waiver of Approvals application for the site was submitted to the DEP on October 2, 1992 and approved on Mach 10, 1993. were Field activities for the Phase II Comprehensive Site Assessment (Phase II)drilling and initiated in October 1993. Supplemental field activities relating to II groundwater sampling were completed in December 1994. The results Phis the Assessment are presented in the body of this report. This the se II RMCP port me0 CMR requirements of both the 1988 MCP (310 CMR 40.545) 40.0830). The Risk Characterization has been prepared in accordance with the Revised MCP (310 CMR 40.0900). 1.1 PURPOSE AND SCOPE ation The purpose of the Phase If Assessment was to conduct a systematic investig and a ent and assessment of the entire site, in order to characterize the nature, p m of oil and/or hazardous materials released at or from the site.The specific objectives of the Phase II were to: delineate the source area of contamination;Lion; define vl locuate the rial posed at the site as they relate to contaminan t fate 1-2 are y95p9a/5261Phasell the U.S. Postal Service property. The Saint John of Cantius Church within the site and Hawley Street transects the site. The consists of property is to an approximately 1.37 acre U.S.US Postal Service pro contain a one-story brick building structure.1 of land, of which a lot n t covered 0 33 building is paved with he Surface of th an asphalt layer e e lot not covered lk provide pedestrian Y or covered with concrete is and vehicular access. �� or sidewalk The Saint John of Cantius property located adjacent to the U.S.Postal Se consists of a 1.85 acre parcel of land, on which three b surface not covered Service fax ered by the buildings is covered buildings are situated.asph The grot (i.e. driveway or sidewalks), or with either concrete or the site p consist buildings, asphalt grassy areas. The remaining portions paved areas associated with Hawley of the site consist Street businesses. awley Street, or parking lots to Hawl Field activities conducted as part of the Phase II Investigation five retractable groundwater probes for included: ins boring/monitoring. groundwater sample collection; installing lbn rung was; Performing aquifer characteristic and soil samples for laboratory alltn fOUr so; testing; collecting gron survey. Between ry analyses; and performing an elevation and location October 6 and 7, 1993, five small were n survey. installed to provide information retractable groundwater were groundwater rmation on the areal extent of the probes contamination The average depth Previous) was approximate) Pth of each groundwater Y detected Y 12 feet below d water table probe s ground surface (anticipated sample point Groundwater samples were P water table de GC. collected from each pthe' The field screening results Probe and screened with the detected in only indicated that elevated concentrations Y one of the samples (GWP_ nis located approximately . Probe GWp_ nO11S of VOCs were ximatl 180 feet from 1 located on the adjacent on m the former gasoline UST. )scent the results of the probe survey, the dissolved ground plume was determined to: 1) have migrated onto the adjacent contaminant relatively narrow�lateral extent, not djacent c1t be extendin feet laterally property; and 2)on the U.S.Posts]Service property more than 40 feet lateral] property. The res of rty and less than 80 feet in the eastern direction the Chu ch results boring/monitoring the groundwater probes n on the Church well locations, were used to optimize the soil Mw- Between March 28 and 29, 1994,four soil boring/monitoring wells , 8 and V-9)were installed to complement the previous) (MW_6D'MW- 7 Y existing six monitoring wells 7-2 30.2/95.09375.25/phasell 7.0 SUMMARY The U.S.Postal Service Northampton Main Post Office is located at 37 Bridge Street in the City of Northampton, Massachusetts. Since the late 1970's, a 4,000 gallon gasoline UST,which was used to refuel post office vehicles, existed at the facility. In August 1989, the tank failed a tank tightness test. At that time, all remaining gasoline in the tank was evacuated. On November 9, 1989, the tank was excavated and removed from the site. A representative of the Northampton Fire Department was on-site during the excavation and reported a small hole on top of the tank. a Preliminary Assessment,Phase 1l,mn[ed Site Between August and September 1991, Investigation, and disposal site classification form were completed f 1 Y e site.The downgradient srofront of the investigation concluded that soil and groundwater imm the former gasoline UST had been impacted front a release of gasoline. A floating separate phase gasoline layer was detected in two monitoring wells installed south of the former UST. There was no separate phase gasoline detected in the furthest downgradient monitoring well(approximately 50 feet from the former UST). However, concentrations of three volatile organic compounds (benzene, toluene, and total xylenes) were detected in groundwater from this well at concentrations in excess of State drinking water standards. Given the direction of groundwater flow and the results of the investigation,the source of the release was determined to be the former gasoline UST. A STM, consisting of a product only recovery system, operated at the facility from February 1992 to November 1994, at which time it was modified to incorporate enhanced product recovery by active depression of the water table surface via groundwater extraction. As of December 30, 1994, approximately 165 gallons of gasoline had been recovered from groundwater at the site. Although variable, product thickness appears to be generally decreasing in the two monitoring wells. The DEP listed the Northampton Post Office as a confirmed disposal site on January 15, 1992. A Waiver of Approvals application for the site was submitted to the DEP on October 2, 1992 and approved on March 10, 1993. The U.S. Postal Service Northampton site consists of the entire U.S. Postal Service property, as well as, several downgradient properties not owned by the U.S.Postal Service, at which field activities were conducted to assess the extent of contaminant migration off 3o 2195,0 375261Phasell 7-1 hydraulic Trcoductint,values rang from 468 to 885 square feet per day and hod vi ranging from 3 short duration aquifer 36 to 68 feet per day were calc quifer test. These values are representative Mated ho: the northern portion of proe ty of the a the site (U.S. Postal S aquifer characteristi The hydraulic conductivity Service property) site (M The nvity of the deep silt and day layer encountered and of the silt layer encountered a site 7) were evaluated by conducting single wear response the central portion a , o9 the site (1 hydraulic conductivity test was �O°So tests. On May r 1994, an in as conducted on monitoring well n October 31, 1994,a test was conducted on monitoring umber mated h and conductivity for the web MW-7. 6o and ivi monitoring we were calculated at 0.012 feet The day(fVday hydra) fVday for MW-7. P day(fVda y)for M Groundwater level measurements were collected from on-site monitoring wells May 6,October 28,and December 30, 1994 to and assess the direction of provide information on aquifer groundwater flow. Based on mets, groundwati depths ranged from 17.28 feet below n these measurements elow ground surface ' grta Se c property,) to 6.31 feet below (MW-2 on the U.S. postal S horizontal hydraulic t bel w round surface (MW-A, 19 Hawley Street well). erag ) The 05 fV (December 30, 1994 data) to 0.008 calculated to range between approximately wate flow in southerly direction. fVft (May 6, 1994 data) with let The vertical calculated roundwater flow is a coup MW-6/MW-6D was approximately 0.03 ft/fted from the water levels at the well site monitoring Using an average site-specific hydraulic conductivity value of 44 fVday and an average horizontal hydraulic gradient ranging rdtoring wells the estimated between 0.005 and 0.008 nmated lateral seepage rou dwaternow is approximately 0.73 to 1.2 fVda P 8e feet per year. shallow y or 266 to 438 feet groundwater flow On April 13 and October 28, pet Yeaz. monitoring , 1994, groundwater samples were ring wells for laboratory analyses. On D collected from from the three monitoring December 20, m eight nitoring wells located in the 19 Hawley groundwater s collected for laboratory arking lot of 19 samples ryanalyses. Groundwater s 9 Hawley from monitoring also wells MW-1 and MW-5 due amPles were not collected from mo to the presence of a floating it°rin% The field chemistry results ' 8 gasoline layer� the wells, units, specific conductance indicated pH values ranged from 25°C) and water tetra ance val esl rangfrom 242 to 1185 microsiemens per o n centimeter at temperature ranged from 6.9 to 16°C. ( 7-4 30.2/95.09375.26/Phasell located on the U.S. Postal Service facility. The soil borings were advanced to an average depth of 20 feet below ground surface. Monitoring well MW-60 was advanced to a depth of 35 feet below ground surface. The well screens were positioned to intersect the water table surface. The well screen of the deep monitoring well (MW-6D)was positioned within the silt and clay unit (approximately 30 to 35 feet below ground surface). Following monitoring well installation,Wehran EMCON conducted an elevation and location moniuey of the on-site monitoring wells and pertinent site features. An additional ati r are locvn ated wells, which were installed in 1994 by others as p of a property within a parking lot along Hawley Street and were utilized during the Phase II Investigation. The ground surface of the site not covered by buildings is primarily covered with a bituminous asphalt pavement layer. Grassy areas are located o the adjacent top s oil church property. Beneath the ground surface, a thin layer of fill encountered. Underlying this fill layer, the subsurface geologic units consisted of: an approximately 5 foot thick sand and silt layer,underlain by an approximately 10 foot thick silt unit with some fine sand, underlain by a medium to coarse sand unit (where present), underlain by a 2 foot thick brown silt unit with fine sand lenses, and a gray silt and clay unit grading into a gray clay layer. the drilling activities using both A total of 37 soil samples were field screened during results indicated that an HNu PID and the portable field GC. The field screening concentrations of VOCs were detected in 8 of the 37 soil samples. Elevated concentrations of V005 were detected in soil samples collected from monitoring wells MW-7 and MW-6D. Volatile organic compounds tentatively identified during the screening activities included: benzene, toluene, ethyl benzene, and xylene (BTEX). To determine the specific characteristics of the on-site water table aquifer the following activities were conducted: a short duration aquifer test; two in-situ hydraulic conductivity tests; and water level measuring. On March 30, 1994, monitoring well MW-5 was pumped at a constant rate of 2.1 gpm for 298 minutes. Maximum drawdowns observed in each well were 3.95 feet (MW-5, test well), 0.33 feet (MW-1), 0.12 feet (MW-6), 0.10 feet (MW-3) and 0.01 feet (MW-4). No change in water level was observed in well MW-2. All water generated during the aquifer testing operations (approximately 975 gallons) was transported off-site to United Waste Oil of Meriden, Connecticut for treatment and disposal. 302/95.0937526/Phasell 7-3 (August 13, 1991) in MW-I and 1.11 feet (May 29 1992) in MW-5. Product thickni these wells as of December 30, 1994 were 0.39 feet in MW-1 and non-detect in MW- separate phase product has been detected in the furthest the U.S.Postal Service property rthest downgraeet from monitoring g MW-1). rtY(MW-6,located approximately 25 feet from moni[orin g Dissolved gasoline constituents predominantly BTBg have been detected in groundwater collected from two monitoring wells (MW-6 and MW_7) contaminants have migrated off the U.S.Postal Service property Disso] onto the adjacent church property P P m'�d approximately 180 1 f from the former pem' (mom[onng well MW-7, located approximately 1801 rmer UST). No concentrations of VOCs were detected in any of the five forth downgradient monitoring wells (MW-A, MW-B, MW-C, MW-8 and MW 9) local approximately 140 to 280 feet from monitoring well MW-7. Although seasonally variab the concentrations of total VOCs detected in groundwater from monitoring well Mw-6 ha remained relatively consistent since 1991. The risk assessment for the site considered the potential risk of ha nn to huma health,public welfare, environment, and public safe ty materials detected at the site. Consideration was iven to both cu tot ndd d easonabi hdot foreseeable future site uses and activities. Potential human receptors included currentposta service employees and customers, residents and employees within the area down the Northampton Post Office, and patrons of Saint John o; environmental receptors (animals, � of Cantius Church. plants, etc.) were specifically While no its urban location,several species were identified as sensitive environmental l receptors the site due to Northampton area. nmental r P in the In the public health, public welfare, and environmental health risk characterization, the potential risk to receptors under both current and reasonably foreseeable fu and activities were evaluated by comparing tore site uses and soil for each e P nog exposure point concentrations ' exposure point location to applicable Standards. groundwater Based on PP�cable MCP Method I or 2 Standards. the results of the risk assessment, there is a significant risk of health, public welfare, and the environment under the current to on the U.S. Postal Service property urrent site use and activity P party only. In contrast, there is no significant of scenario health,public welfare, and the environment and of harm to vironment under the current site use and activity scenario 7-6 30 2/95.0937526/P h asell The analytical results indicated that concentrations of VOCs were deter ee wells (MW-6, MW-6D, and ethyl benzene; total xylenes; 1,2,4-trichlorobenzene; of the eight monitoring 1,3,5- included: benzene; toluene; n-propylbenzene; chloroform; n-butylbenzene; is opropylbenzene; naphthalene; trimethylbenzene; and 1,2,4-[rimethylbenzene. It should be noted that all of the detected t chloroform, can be associated with gasoline. No VOCs were detected above t in the samples collected from monitoring wells MW VOCs, except the laboratory's-S W , MW method detection M A MW-B, MW MW-9, and MW-C. No elevated concentrations of 2 MW-3, or Iota M MW-S, (MW-3) were detected in background concentrations ( naphthalene; dissolved or total metals compared to b volat organic compounds including P any of the samples analyzed. Five semi-volatile o 4 dim Y P 1-methylnaphthalene; 2-methylnaPhthalene; 2, eth 1 henol; and total cresol were sample from monitoring well MW-6. indicated detected in the slme C samples submitted for analytical testing The results from the d g and analytical testing procedures were followed. proper sample collodion,handling, No concentrations of VOCs above ambient air background headspace detected in the samples field screened by the soil jar any in of the unsaturated soft samp and adjacent Church drilling activities conducted on the U.S. Postal Service property samples from three of the no concentrations of VOCs in ambient air samp property. s located were ambient air (using the PID) were catch basins located adjacent to the former UST on the U.S. Postal Service property detected with the ND. No concentrations of V005 in recorded in the adjacent church property basement or crawl sp ace. soils situated at or beneath the wOCr table Based on this data and the fact that only so appear to be any appear to be impacted by contaminants, there does not app emissions emanating from the subsurface beneath the site to the ground surface.gasoline layer has been observed floating on the water Since 1991, a separate phase S A product only table surface in two of the on-site monitoring wells (MW-1 and MW-5) orated at the site (MW-5) from February 1992 to November 1994. recovery system had op 1992. As of Monthly hand bailing of product from MW-1 has also occurred since Fe rim December 1994, approximately 165 gallons of gasoline has been removed from the groundwater at the site. Although layer is generally decreasing. Maximum variable, the thickness of this Y were measured at 3.07 feet product thickness in monitoring wells MW-1 and MW-5 30 2195 09375 261Phasell 7-5 for the adjacent church property with respect to the dissolved VOC contaminant plume, which has migrated off the U.S. Postal Service property. reasonably The results of the risk assessment is site indicates that orn on ante off she U.B. foreseeable future site use and activity scenario, to health, Postal Service property (Church property) could pose a significant risk of harm public welfare, and the environment due to contaminant concentrations in groundwater in excess of applicable Method 1 Standards. 302/95.0937526/P6asell 7-7 under the 1993 MCP and a Tier II Classification Extension will be submitte d to cont response actions. 8-2 302/95.09375.26/PhaseII 8.0 CONCLUSIONS Based on the results of the investigative asesccn du edtathe site.site, a release of of at petroleum product (gasoline) to the groundwater which was the release was either leakage or spillage from a 4,000 gallon gasoline UST, product layer on top of the groundwater exists within a limited removed from the site in 1989. A separate phase p lume in groundwater, area on the U.S. Postal Service property. A dissolved VOC p predominantly BTEX compounds,has migrated off the U.S.Postal Service property with bulk th b buulk groundwater flow onto the adjacent church property (monitoring well MW-7, located approximately 180 feet from the former UST). No concentrations of VOCs were detected in any of the five further downgradient monitoring wells located approximately 140 to 280 feet from monitoring well MW-7• risk of harm to Based on the results of the risk assessment, there iiss`t s significant and risk of harm to health,public welfare, and the environment under the curt a risk of harm to on the U.S. Postal Service property only. In contrast,there is no significant health,public welfare, and the environment under the current site use and activity scenario for the adjacent church property with respect to the dissolved VOC contaminant plume, which has migrated off the U.S. Postal Service property.As mentioned previously, the STM has been modified and is currently extracting groundwater and separate phase product from beneath the U.S. Postal Service property and will continue to operate. The results of the risk assessment Pa also indicates d cater that under er the off foreseeable future site use and activity risk of harm theU U.S..S. Postal Service property (Church property) could pose a rm to heal in public welfare, and the environment due to contaCminaauntcoT remedial ons in groundwater actions, to excess of applicable Method 1 Standards. As incorporate the adjacent property downgradient of the U.S. Postal Service property, are required to achieve a condition of No Significant Risk. The Waiver requires that within five years of the waiver approval (by March 1998), a completion statement,indicating whether the implemented remedial response actions have achieved a permanent solution, must be submitted to the DP. I become a Tition hasp er not been achieved by March 1998, then the site will categorically 30.J95.09375 261Phasell 8-1 iiiiiii Commonwealth of Massachusetts Executive Office of Environmental Affairs Department of Environmental Protection Western Regional Ilam F. Weld 9U rudy Coxe crewy. MCA nas S. Powers :Ong commissioner September 8, 1994 larles Vidich ivironmental Compliance Coordinator cited States Postal Service )rtheast Area Office Griffin Road 06006-'1000 indsor, Re: Northampton 1-0901; Waiver U.S . Post Office Bridge Street M.G.L. Ch. 21E Dear Mr. Vidich: Department) has a Short ctio Measure D (art at the The Department of Environmental modify horte Termn (the ep your t the d site .to moThey request was prepared on y received a request of Andover, Massachusetts and ndvreceive above referenced site . The by the Wehran artme (Wehran)August 1994 . A Waiver of App by the Department on 9 (waiver) was granted for this site on 10 March ongoing Sconsisting roved, there was an ong Wngl STM M 5 In When the waiver was app well was of an automatic at tw twelve ) inch diameter recovery insy lled. a he pro (s2) proposed modification of tSewSth an automatic installed. ehep P well . system in the twelve inch recovery with replacing the automatic bailer in well holding tank equipped Recovered recovery Y to a t create rtecti will be pumped um will be usedct"capture Recovered p groundwater pump provide a P overfill of protection. in g a cone of depression in the water table and p zone" for the product . with an air stripper equipped using liquid phase carbon. Treated Groundwater will be treated using to surface waters off-gas treatment by groundwater is anticipated ipated to be discharged under a USEPA NPDES permit . confirms the verbal approval of h STM modification conveyed to Jeff Hamel of Wehran on 15 August 436 Dwight Street • Springfield, Massachusetts 01103 FAX(413)784-1149 • Telephone(413)784-1100 2 901 reports must be submitted to the Department for reports must include a summary of the �rterly status rep should, at a is site. and status pof the STM. The summary as well as a ac es any and screening results, eration discharged. port , include thamount uny water treated and port of the amount of lease contact you have any questions regarding this matter, P :ephen Ball of this office. Sincerely, [� cy. Catherine G. Wanat Section Chief Management Audits/Site Bureau of Waste Site Cleanup CGW:SSB/mr hamppo. stm Mayor' s Office cc:Northampton, Northampton, Board of Health Jeff Hamel, Wehran EMCON �Wehran Emcon Northeast February 24, 1995 Mayor Mary Ford City of Northampton City Hall 210 Main Street Northampton, Massachusetts 01060 RE: Phase H Comprehensive Site Assessment Report U.S. Postal Service Main Office, Northampton, MA 01060 EMCON Project No. 09375.26 Six Riverside Drive Suite 101 Andover,MA 01810-1121 Tel. (508)682-1980 Fax: (508)975-2065 Dear Mayor Ford: On behalf of the United States Postal Service, EMCON has completed a Phase II Comprehensive Site Assessment for the U.S. Postal Service main office located at 37 Bridge Street. Pursuant to 310 CMR 40.1403(3)(e) of the Massachusetts Contingency Plan (MCP) (Public Involvement Activities), this letter serves as notification of the submittal of the Phase II Report for the above-mentioned site to the Massachusetts Department of Environmental Protection (DEP). Please find attached to this letter, several sections of the report which summarize the results and conclusions of the investigation. These sections include: Section 1.0 which presents a site history and introduction, Section 7.0 which presents a summary of the activities performed at the site, and Section 8.0 which presents the conclusions of the investigation. A site map is also provided showing the locations of the sampling points. The complete Phase II Comprehensive Site Assessment Report, as well as other documents pertaining to the site, may be obtained at the DEP Western Regional Office, located at 436 Dwight Street, Suite 402, Springfield, Massachusetts, (413) 784-1100. Please reference DEP Site Number 1-0901.