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6. Mill River Levee System_Interim Stability Analyses Memo_3-3-21 An Equal Opportunity Employer M/F/V/H M E M O R A N D U M To: David Veleta (Northampton, DPW) Kris Baker (Northampton, DPW) From: Matthew A. Taylor, P.E. (GZA) Christopher Baker, P.E. (GZA) Yixing Yuan, Ph.D. (GZA) John DeLano, P.E. (GZA) Date: March 3, 2021 File No.: 01.0174343.00 Re: Interim Geotechnical Analyses Memorandum Engineering Services for Levee Certification Mill River Levee System Northampton, Massachusetts GZA GeoEnvironmental, Inc. (GZA) is pleased to present this memorandum to the City of Northampton Department of Public Works (DPW), summarizing our interim geotechnical analyses efforts for the Mill River Levee System. A similar memorandum summarizing the interim geotechnical analyses for the Connecticut River Levee System has been provided under separate cover. This work was conducted in accordance with Task 4 of our agreement (WF7- 19-2019) dated July 19, 2019, and is subject to the Limitations provided in Appendix A. GZA has completed the subsurface exploration program for Mill River Levee System (System) between December 12, 2019 and January 14, 2020 and collected the necessary data to support the geotechnical (i.e. seepage, slope stability, wall stability, and settlement) analyses for the System. The subsurface exploration program and the associated data-collection works were summarized in our Geotechnical Data Memorandum for the System dated December 22, 2020. The engineering analyses presented in this memorandum are conducted to support the levee system certification and eventual Federal Emergency Management Agency (FEMA) accreditation in under Regulation 44 CFR 65.10. The interim geotechnical analyses completed to date utilized the currently available hydrologic and hydraulic (H&H) information for the Mill River Levee System. The river levels for 100-year flood and normal conditions were obtained from 1978 Flood Insurance Rate Maps (FIRMs) and converted from NGVD29 to NAVD88 by using the USGS datum conversion tool. However, in 2020, FEMA began to update the H&H model for the Mill River, which will result in different 100-year flood elevations (i.e. Base Flood Elevations) in the river. FEMA’s updated H&H model will reportedly be available in 2021/2022. GZA will update the geotechnical analyses for the system once the updated H&H model is made available. March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 2 Proactive by Design BACKGROUND MILL RIVER LEVEE SYSTEM In response to significant flooding events in the 1920’s and 1930’s, the United States Army Corps of Engineers (USACE) designed and constructed flood control works along the Mill River to protect the City of Northampton (City), Hampshire County, Massachusetts. The Work was authorized under the Flood Control Act, approved on June 22, 1936, and construction along the Mill river was conducted over a series of contracts between December 1938 and June 1942. In 1944, the City accepted responsibility to operate and maintain the Mill River Levee System (System) in accordance with the Flood Control Regulations. Refer to Figure 1 for a Locus Map of the System. Refer to Appendix B for relevant System Record Drawings obtained from the 1945 Operations and Maintenance (O&M) Manual. The Mill River Levee System protects the western part of the City against high water from the Mill River. The Mill River Levee System consists of earthen levee, concrete flood wall, and a diversion channel and is approximately 2,400 feet in total length. The Smith College Dike is the most upstream component of the System; its upstream end is located about 70-feet downstream of the Paradise Pond Dam. The Smith College Dike has a maximum height of about 16-feet and extends southward along the east bank of the Mill River about 1,100-feet to West Street from Station (Sta.) M 0+71 to Sta. M 11+57. At West Street, a 50-foot wide and 14.5-foot-tall stop log closure structure is provided from Sta. M 11+57 to Sta. M 12+04, which is located between the Smith College Dike and a downstream concrete floodwall (floodwall). The Floodwall of “T” type cantilever construction has a maximum height of about 21-feet and extends approximately 450-feet from about Sta. M 12+00 to Sta. M 16+52 tying in a downstream dike (Diversion Dike). To control underseepage below the Flood Wall and a portion of the Diversion Dike, a steel sheetpile cut off was installed between Sta. M 11+33 and Sta. M 19+72. The Floodwall has a 20-foot-wide opening provided for the former New York, New Haven, and Hartford Railroad, which has been converted into a paved “Rail Trail”. The Diversion Dike has a maximum height of about 25-feet and extends approximately 900-feet from Sta. M 16+50 to high ground at Hebert Avenue at Sta. M 23+50. This Diversion Dike protects the east overbank area and also diverts the Mill River to a diversion canal (Diversion Canal). SCOPE OF WORK GZA’s Scope of Work for the Mill River Levee System – Task 4 – Engineering Analyses and Evaluations includes levee embankment seepage and stability (Task 4.1), levee embankment settlement (Task 4.2), structural stability/adequacy of floodwalls (Task 4.3), and interior flooding of areas protected by the levee system (Task 4.4). This memo summarizes the portion of the scope of work completed to date for Tasks 4.1, which includes the subsurface data interpretation, analysis cross section, and interim seepage and slope stability analysis and results. The specific scope of work highlighted herein includes the following: 1. Develop subsurface cross-sections and profiles at the specified locations for the proposed geotechnical analyses, based on the information derived from the existing explorations and GZA’s recent exploration program. 2. Develop the soil parameters to be used in the geotechnical analyses based on correlations with the in-situ exploration results and laboratory data collected from subsurface exploration program. 3. Perform initial seepage analyses to evaluate the location of phreatic surface and pore pressures within and below the levee embankment, along with the exit gradient on the landside of the levee embankment March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 3 Proactive by Design sections under normal condition, flood condition and rapid drawdown conditions. These initial seepage analyses conservatively assumed non-functional toe drains and neglected the benefit of the cut-off wall beneath certain sections of the levee. 4. Perform initial slope stability analyses to evaluate the factor of safety for the critical slip surface in the levee embankment cross-sections under different loading conditions, including normal condition, flood condition, rapid drawdown, and seismic (pseudostatic) loading. 5. Prepare the interim geotechnical analysis memorandum to summarize our initial findings. LEVEE EMBANKMENT CROSS-SECTION AND PROFILE DEVELOPMENT GZA developed levee embankment cross-sections and subsurface profiles to perform the required geotechnical analyses at the specified locations near Stations 6+00, 9+00, 18+00, 20+00, 22+00 in the Mill River Levee Embankment. Refer to Figure 2 for the locations for the analysis cross sections. The analysis sections were selected by considering the boring locations proposed in our agreement (WF7-19-2019) dated July 19, 2019, and the location of USACE typical design sections (1939 Record Drawing of Embankment Details, Plate XIII, as included in Appendix B). These sections were selected to represent the critical variations in the embankment design details, the topography, and also in “worst-case” conditions based on the subsurface soil profile along the Mill River levee. The geometry and stratigraphy for each section profiles were initially derived by using Leapfrog Works (ver. 3.1.1), a 3D geological modeling software developed by SEEQUENT company. Using Leapfrog, GZA created a 3D geological model for Mill River Levee, as shown in Appendix C, by integrating a Digital Elevation Model (DEM) for the current topography (USGS 2015 1), the longitudinal subsurface profile of the System as shown on Plate XV A of the 1945 O&M Manual, and new subsurface information obtained from the 2019/2020 subsurface exploration program conducted by GZA. GZA then extracted a soil profile cut along the levee axis in the model near Station 6+00, 9+00, 18+00, 20+00 and 22+00, as shown in Appendix C. The soil profile shown on the Leapfrog 3D model were based on preliminary interpretation of the subsurface boring information with simplified stratigraphy. The extracted subsurface profile was then imported into the GeoStudio Suite (v2021, SEEQUENT) to establish the model cross-sections and stratigraphy for the proposed seepage and slope stability analyses at Stations 6+00, 9+00, 18+00, 20+00, 22+00, as included Appendix D. The elevations in these cross-sections are referenced to the North American Vertical Datum of 1988 (NAVD88). SOIL PARAMETER DEVELOPMENT GZA developed the soil parameters for the seepage and stability analyses based on correlations with the in-situ exploration results and laboratory data collected from previous and 2019/2020 subsurface exploration programs, as listed in Table 1. Refer to GZA’s Geotechnical Data Memorandum dated December 22, 2020 for previous test boring data, 2019/2020 test boring logs and 2020 geotechnical laboratory test results. 1 USGS Lidar DEM: Maine & Massachusetts 2015 QL1 & QL2 Lidar dataset, https://www.fisheries.noaa.gov/inport/item/49407 March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 4 Proactive by Design The saturated hydraulic conductivity (permeability) values used in the seepage analyses, listed in Table 1, were estimated from grain-size correlations 2,3,4,5 and published values for similar materials. The saturated unit weights and the total strength values for all the materials were estimated based on published typical values for similar materials, and GZA’s engineering experience. The effective strengths for the cohesionless fill materials were estimated based on empirical correlations with the SPT-N values obtained from 2019/2020 borings. The undrained strength profile for the varved clay layer was estimated based on published values in the studies on Connecticut Valley Varved Clay (CVVC)6,7. The summary of the effective strengths estimated for the cohesionless soils and the referenced strength values for the CVVC layer is included in Appendix D. Table 1. Material Parameters used in GZA’s Seepage and Stability Analyses Strata Total Unit Weight, γt (pcf) Effective Strength Parameters Total Strength Parameters Saturated Horizontal Hydraulic conductivity, ksat Cohesion, c' (psf) Friction Angle, φ'(°) Cohesion (psf) Friction Angle, φ(°) ft/s cm/s Topsoil Fill* 120 0 31 100 10 4.2E-07 1.3E-05 Overlying Fill** 120 0 30 Same as effective strength 4.3E-04 1.3E-02 Impervious Blanket Fill 120 0 32 200 10 4.2E-07 1.3E-05 Riprap 145 0 40 Same as effective strength 1.0E-01 3.0E+00 Random Fill 125 0 34 500 11 1.5E-06 4.6E-05 Silt & Clay 110 0 28 300 10 2.9E-08 8.9E-07 Sand*** 120 0 30 Same as effective strength 3.5E-04 1.1E-02 Selected Impervious Fil (Impervious core) 120 0 32 800 0 7.3E-10 2.2E-08 Varved Clay 110 su increases with depth**** su = 500psf 2.0E-07 6.1E-06 Weathered Bedrock 130 0 45 1000 0 7.3E-09 2.4E-07 * Topsoil Fill represents the Topsoil Fill and Gravel Base course encountered in test borings **Overlying Fill represents the fill material outside of the levee embankments at the landside and/or riverside toe, overlying the existing natural material, and is not a layer that is shown on the recent boring logs *** Sand corresponds to the Gravel and Sand encountered beneath Random Fill in the test borings. ****The su strength profile used in the stability analyses is included in the attachment of Appendix D 2 Slichter, Charles S. 1905, Field measurements of the rate of movement of underground waters, U. S. Geological Survey Water Supply Paper 140: 106 pp 3 Sherard, J.L., Dunnigan, L.P., and Talbot, J.R., 1984, Basic Properties of Sand and Gravel Filters. ASCE Journal of Geotechnical Engineering, v.110 #6, June 1984, p.684-700 4 Hazen, A. (1911) Discussion: Dams on Sand Foundations Trans. ASCE, vol. 73 p.199 5 Terzaghi, Peck, & Mesri, Soil Mechanics in Engineering Practice, 3rd Ed, 1996 6 DeGroot, D.J. & Lutenegger A.J. (2002) Geology and Engineering Properties of Connecticut Valley Varved Clay, International Workshop on Characterization and Engineering Properties of Natural Soils, Singapore, December 2002 7 Ladd, C.C., and Wissa, A.E.Z, (1970) Geology and Engineering Properties of Connecticut Valley Varved Clays with Special Reference to Embankment Construction, MIT Research Report R70-56, Department of Civil Engineering, Massachusetts Institute of Technology, September 1970, p154. March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 5 Proactive by Design GZA identified some isolated pockets of the artificial fill/existing fill (as indicated on the O&M Plan, Plate XV A) beneath the embankment fill in the recent borings, but the transition from these existing fills to the engineered embankment fill materials (e.g., Random Fill or Selected Impervious Fil in the Diversion Dike) was not obvious based on visual classification. The initial analyses assumed the artificial/existing fill layers same as the engineered embankment fill materials. Additional laboratory testing completed during a later phase in the assignment will be used to refine the soil stratigraphy and the engineering parameter assignments, where necessary. SEEPAGE ANALYSES GZA performed steady-state seepage analyses for selected cross-sections of the Mill River Levee Embankment under normal conditions and the flood conditions using the Seep/W program, a two-dimensional finite element seepage analysis software (included in GeoStudio suite 2021) developed by SEEQUENT. The analyses allow estimation of the location of the phreatic surface through the embankment, the pore pressures, and the exit gradients at specific finite element nodes at the landside toe of the embankment. The material parameters used in the steady seepage and stability analyses are listed in Table 1. The river levels for 100-year flood and normal conditions at the selected cross-sections were obtained from the 1978 Flood Insurance Rate Maps (FIRMs), which were based on a Flood Insurance Study in 1976 (Appendix B). FEMA is currently updating the hydrologic and hydraulic model for the Mill River and will be issuing an updated Flood Insurance Study in the next few years. As such, revised 100-year flood elevation (i.e. Base Flood Elevations) will be generated. At the time, an update of the seepage and associated stability calculations for the flood case will be required. The landside water level for each of the selected cross sections was conservatively assumed to be at the landside ground surface under normal conditions. Based on existing exploration data shown on record drawing (Appendix B), the landside groundwater levels are typically below the ground surface. The impacts of the landside groundwater levels will be re-visited in conjunction with a sensitivity evaluation of the functionality of the toe drain and its impact on the calculated factors of safety during a later phase of the analyses. Although the Mill River Levee was constructed with a toe drain on the landside and steel sheetpile cut off (beneath a portion of the Diversion Dike), based on the record drawings in Appendix B, previous toe drain functionality and effectiveness evaluation have been inconclusive, and the sheetpile locations have not been confirmed. The 2016 AECOM toe-drain inspection 8 for Mill River levee system indicates that “approximately 1,441 linear feet of toe drain was not inspected due to defects such as broken or collapsed pipe”. As such, GZA conservatively ignored the effects of the toe drains for the interim steady state seepage analyses described herein. GZA also conservatively neglected the benefit of the sheetpile cutoff wall at sections of levee where one was installed. For the flood case, the seepage model was used to predict the location of the phreatic surface within the levee embankment starting from the landside ground surface, assuming a non-functioning toe drain, as the initial starting point. Appendix E summarizes the graphic results of the steady-state seepage analyses for Mill River levee for the specified sections under normal and flood level conditions. The calculated seepage gradients at the landside toe of the levee under the analyzed river conditions do not appear to exceed the critical gradient as required by the US Army Corps. Of Engineers (USACE) 9, as shown in Table 2, below. The results also indicate that the seepage 8 AECOM, May 19, 2016 “Mill River Levee and Flood Control System Assessment Summary Report” 9 USACE EM1110-2-1901, "Seepage Analysis and Control for Dams" March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 6 Proactive by Design flow rate calculated at the landside toe is relatively high in several sections (near Sta. 6+00, 9+00, 18+00) under the flood conditions without toe drain, which is likely due to the relatively permeable sand layer underlying the embankment and neglecting the presence of a cutoff. To GZA’s knowledge, there is no limiting criteria on the amount of seepage flow rate at the landside toe, but it is good practice to limit seepage quantities into the protected areas of the levee. Table 2. Water Levels and Calculated Exit Gradients for Seepage Analyses River Elevation Critical Gradient* Exit Gradient Station 6+00 9+00 18+00 20+00 22+00 100yr Flood 0.5 <0.1** <0.1 <0.1 <0.1 <0.1 Normal Conditions 0.5 <0.1 <0.1 <0.1 <0.1 <0.1 * the critical gradient required by US Army Corps. Of Engineers (USACE) 8 ** Negligible seepage gradients calculated at landside toe are indicated as <0.1 SLOPE STABILITY ANALYSES GZA performed slope stability analyses for the riverside and landside slopes of Mill River Levee Embankments and calculated a factor of safety against slope instability under various loading conditions. The slope stability models were created using SLOPE/W, a two-dimensional limit equilibrium slope stability modeling software included in the GeoStudio Suite. Factors of safety against slope instability were estimated by the Spencer Method as implemented by SLOPE/W. Porewater pressures developed from the previously-described steady state seepage analyses were directly input by the software into the slope stability analyses, so that the models were able to consider seepage forces and phreatic surfaces. The material parameters used in the slope stability analyses are listed in Table 1. The stability of the riverside slope of the levee embankment under “rapid drawdown” from flood conditions to the normal level of the Mill River was performed using the USACE three-stage method as implemented by SLOPE/W. The slope stability under seismic loading was also evaluated using a pseudo static approach under normal condition. Based on USACE guidance 10 , GZA used the 2/3’s of a regionally developed peak ground acceleration (PGA) value by USGS 11, with a return period of 2,475 years as the input for the pseudo static seismic analysis. The resulting acceleration used in the analyses was 0.12g. The graphical output for the Slope/W stability analyses, including the critical failure slip surfaces and their associated factors of safety are presented in Appendix E. The factors of safety for the riverside and landside slopes were calculated under the loading conditions listed in Table 3. The calculated factors of safety meet or exceed the minimum required values as outlined by USACE guidance12 with the exception of the riverside stability near Sta. 20+00 under seismic load. The graphic result for Sta. 20+00 under seismic load indicates that the calculated critical slip surface passes through the varved clay (CVVC) layer, where its undrained strength profile needs further investigation. 10 USACE EM1110-2-6053, “Earthquake Design and Evaluation of Concrete Hydraulic Structures” 11 USGS Seismic Design Maps webtool, https://earthquake.usgs.gov/ws/designmaps March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 7 Proactive by Design Table 3. Slope Stability Analysis Results for Mill River Levee Loading Condition Levee Face Factor of Safety Minimum Required* Station 6+00 9+00 18+00 20+00 22+00 100-year Flood (Steady State) Landside 1.4 1.5 1.6 1.8 1.9 1.6 Riverside 1.7 1.6 2.1 2.1 2.2 Sudden Drawdown - 100-year Flood Landside 1.0 - 1.2 1.2 1.4 1.4 1.4 2.5 Normal Conditions Landside 1.4 1.5 1.5 2.1 2.1 1.8 Riverside 1.7 1.5 1.5 1.5 2.7 Seismic (Pseudostatic, normal conditions) Landside 1.0 1.2 1.2 1.4 1.3 1.4 Riverside 1.2 1.0 1.0 0.9 1.3 * Required factors of safety are based on USACE guideline 12 except for seismic case, where a minimum factor of safety greater than 1.0 is typically used in dam engineering practice. CONCLUSIONS GZA offer the following conclusions: • Portions of the artificial fill/existing fill identified below the bottom of the levee/flood wall as shown on the O&M Plan (Plate XV A), was apparently partially removed prior to the construction of portions of the levee embankments. An apparent isolated pocket of the artificial fill/existing fill was identified at the upstream end of the Smith College Dike and adjacent to the floodwall section. The transition between artificial fill/existing fill below the Diversion Dike was not obvious based on the visual classification. Additional laboratory testing is necessary to refine the soil stratigraphy/engineering parameter assignment, specifically below the Diversion Dike. • The interim steady seepage analyses results indicate that the Mill River Levee Embankment adequately meets the criteria against piping under normal conditions and 100-yr flood conditions even with conservative landside water levels assumptions and ignoring the sheetpile cutoff and toe drain functionality. However, when the presence of a cutoff or toe drain is ignored, relatively large subsurface seepage flows are predicted by the models below the landside toe of the levees. • The slope stability analyses results suggest that most portion of the Mill River Levee meets the required factor of safety for slope stability of the riverside and landside slopes under loading conditions specified in EM 1110-2-1902, with the exception of the Section near Sta. 20+00. The riverside slope of Section 20+00 yielded marginally low factors of safety under seismic load conditions. • The slope stability factors of safety in some areas of the levee are significantly dependent on the strength properties of the existing fill layer and the underlying CVVC deposit. 12 USACE EM1110-2-1902, “Slope stability” March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 8 Proactive by Design RECCOMENDATIONS GZA offer the following recommendations: • A sensitivity analysis should be performed to determine if a functional toe drain and cutoff would reduce the seepage flow quantity below the landside toe in the sections of Sta. 6+00, 9+00, and 18+00 under the flood conditions. If the analysis results suggest that a functional toe drain can effectively improve the results, GZA would likely recommend confirming the working status of the toe drains. • Additional review of the subsurface information collected during the 2019/2020 subsurface exploration program should be performed to identify samples for additional laboratory testing including strength testing, index testing, and consolidation testing. The results of which should be used to refine the subsurface soil stratigraphy used for the model development and the assignment of soil parameters used in the geotechnical analyses. The results of the additional laboratory testing should be used to update seepage and stability analyses, where appropriate, as well as to support the subsequent levee embankment settlement analyses and flood wall stability analyses. • GZA recommends performing laboratory tests on the varved clay samples to refine the estimate of the undrained shear strength profile. Given that these soils have been subjected to over 60 years of consolidation under the levee embankments, an increase in strength over time would be expected. o This is particularly important for the pseudostatic analyses, some of which are marginally low or below the required values and could potentially be worse if a larger acceleration or lower clay strength is considered. • If the laboratory strength tests are unable to provide a refined estimated of the varved clay strengths (either due to sample disturbance or inability to capture in-situ stress and or porewater conditions), seismic cone penetration test (SCPT) testing in areas of the Mill River Levee where of the varved clay was encountered should be considered to allow for site-specific strengths to be better categorized. o Additionally, the SCPT probes would allow for a better understanding of how the CVVC deposits respond to seismic forces. REMAINING TASKS TO BE COMPLETED In accordance with our agreement (WF7-19-2019) dated July 19, 2019, GZA has the following tasks to be completed: • Task 4.1 – Levee Embankment Seepage and Stability Analysis – Finalize the analyses after FEMA issues the updated H&H data for the Connecticut River System. • Task 4.2 Levee Embankment Settlement Analysis – Complete the analysis for one (1) representative cross section of the Mill River Levee System. The analysis should be performed after consolidation testing has been completed; and March 3, 2021 File No. 01.0174343.00 Interim Geotechnical Analyses Memo – Mill River Levee System Page | 9 Proactive by Design • Task 4.3 Evaluation of the Floodwall Stability for two (2) cross sections for the Mill River Levee System – The analysis should be performed in a similar manner as the levee embankment seepage and stability analyses (i.e. interim and then final once the H&H data has been issued). • The interim geotechnical analysis memorandum will be updated with the final results of Task 4.1 to 4.3. CLOSING We trust that the information contained in this memorandum meets the City’s needs at this time Please feel free to contact us if you have any questions or comments regarding the content of this memorandum. Figures Figure 1 – Locus Plan Figure 2 – Analysis Cross-Section Location Plan Appendices: Appendix A – Limitations Appendix B – Record Drawings and Existing Flood Level Information Appendix C – 3D Leapfrog Model Screenshots Appendix D – Model Parameters Appendix E – Output for Seepage and Slope Stability Analyses Proactive by Design FIGURES PROJ. MGR.: CLB DESIGNED BY: YY REVIEWED BY: CLB OPERATOR: YY DATE: 8-26-2019 JOB NO. 401,000 2,000500 SCALE IN FEETUSGS QUADRANGLE LOCATION © 2020 - GZA GeoEnvironmental, Inc., J:\170,000-179,999\174343\174343-00.CLB\Memos\Stability\CT Levee Appendix\Figures\Figure 1 - LOCUS PLAN - Northampton-12-29-2020.mxd, 12/29/2020, 2:54:48 PM, Yixing.yuanCONNECTICUT RIVER & MILL RIVER LEVEENORTHAMPTON, MASSACHUSETTS FIGURE NO. 01.174343.00 1 SOURCE: THIS MAP CONTAINS THE BING MAPS AERIAL ONLINE MAP SERVICE. LOCUS PLAN Legend E Station Floodwall Levee A GZA_Boring PROJ. MGR.: CLB DESIGNED BY: YY REVIEWED BY: CLB OPERATOR: YY DATE: 8-26-2019 JOB NO. 401,000 2,000500 SCALE IN FEETUSGS QUADRANGLE LOCATION © 2020 - GZA GeoEnvironmental, Inc., J:\170,000-179,999\174343\174343-00.CLB\Memos\Stability\Mill Levee Appendix\Figures\Figure 2 -SECTION LOCATION -MillRiver - Northampton-12-29-2020.mxd, 12/31/2020, 12:32:26 PM, Yixing.yuanMILL RIVER LEVEENORTHAMPTON, MASSACHUSETTS FIGURE NO. 01.174343.00 2 SOURCE: THIS MAP CONTAINS THE BING MAPS AERIAL ONLINE MAP SERVICE. ANALYSES SECTION LOCATION Legend E Station Floodwall Levee CrossSection A GZA_Boring Proactive by Design APPENDIX A LIMITATIONS GEOTECHNICAL LIMITATIONS File No. 01.0174343.00 Page | 1 October 2020 Proactive by Design USE OF REPORT 1. GZA GeoEnvironmental, Inc. (GZA) prepared this report on behalf of, and for the exclusive use of our Client for the stated purpose(s) and location(s) identified in the Proposal for Services and/or Report. Use of this report, in whole or in part, at other locations, or for other purposes, may lead to inappropriate conclusions; and we do not accept any responsibility for the consequences of such use(s). Further, reliance by any party not expressly identified in the contract documents, for any use, without our prior written permission, shall be at that party’s sole risk, and without any liability to GZA. STANDARD OF CARE 2. GZA’s findings and conclusions are based on the work conducted as part of the Scope of Services set forth in Proposal for Services and/or Report, and reflect our professional judgment. These findings and conclusions must be considered not as scientific or engineering certainties, but rather as our professional opinions concerning the limited data gathered during the course of our work. If conditions other than those described in this report are found at the subject location(s), or the design has been altered in any way, GZA shall be so notified and afforded the opportunity to revise the report,as appropriate, to reflect the unanticipated changed conditions . 3. GZA’s services were performed using the degree of skill and care ordinarily exercised by qualified professionals performing the same type of services, at the same time, under similar conditions, at the same or a similar property. No warranty, expressed or implied, is made. 4. In conducting our work, GZA relied upon certain information made available by public agencies, Client and/or others. GZA did not attempt to independently verify the accuracy or completeness of that information. Inconsistencies in this information which we have noted, if any, are discussed in the Report. SUBSURFACE CONDITIONS 5. The generalized soil profile(s) provided in our Report are based on widely-spaced subsurface explorations and are intended only to convey trends in subsurface conditions. The boundaries between strata are approximate and idealized, and were based on our assessment of subsurface conditions. The composition of strata, and the transitions between strata, may be more variable and more complex than indicated. For more specific information on soil conditions at a specific location refer to the exploration logs. The nature and extent of variations between these explorations may not become evident until further exploration or construction. If variations or other latent conditions then become evident, it will be necessary to reevaluate the conclusions and recommendations of this report. 6. In preparing this report, GZA relied on certain information provided by the Client, state and local officials, and other parties referenced therein which were made available to GZANat the time of our evaluation. GZA did not attempt to independently verify the accuracy or completeness of all information reviewed or received during the course of this evaluation. 7. Water level readings have been made in test holes (as described in this Report) at the specified times and under the stated conditions. These data have been reviewed and interpretations have been made in this Report. Fluctuations in the level of the groundwater however occur due to temporal or spatial variations in areal recharge rates, soil heterogeneities, the presence of subsurface utilities, and/or natural or artificially induced perturbations. The water table encountered in the course of the work may differ from that indicated in the Report. 8. Recommendations for foundation drainage, waterproofing, and moisture control address the conventional geotechnical engineering aspects of seepage control. These recommendations may not preclude an environment that allows the infestation of mold or other biological pollutants. GEOTECHNICAL LIMITATIONS File No. 01.0174343.00 Page | 2 October 2020 Proactive by Design COMPLIANCE WITH CODES AND REGULATIONS 9. We used reasonable care in identifying and interpreting applicable codes and regulations. These codes and regulations are subject to various, and possibly contradictory, interpretations. Compliance with codes and regulations by other parties is beyond our control. COST ESTIMATES 10. Unless otherwise stated, our cost estimates are only for comparative and general planning purposes. These estimates may involve approximate quantity evaluations. Note that these quantity estimates are not intended to be sufficiently accurate to develop construction bids, or to predict the actual cost of work addressed in this Report. Further, since we have no control over either when the work will take place or the labor and material costs required to plan and execute the anticipated work, our cost estimates were made by relying on our experience, the experience of others, and other sources of readily available information. Actual costs may vary over time and could be significantly more, or less, than stated in the Report. SCREENING AND ANALYTICAL TESTING 11. We collected environmental samples at the locations identified in the Report. These samples were analyzed for the specific parameters identified in the report. Additional constituents, for which analyses were not conducted, may be present in soil, groundwater, surface water, sediment and/or air. Future Site activities and uses may result in a requirement for additional testing. 12. Our interpretation of field screening and laboratory data is presented in the Report. Unless otherwise noted, we relied upon the laboratory’s QA/QC program to validate these data. 13. Variations in the types and concentrations of contaminants observed at a given location or time may occur due to release mechanisms, disposal practices, changes in flow paths, and/or the influence of various physical, chemical, biological or radiological processes. Subsequently observed concentrations may be other than indicated in the Report. ADDITIONAL SERVICES 14. GZA recommends that we be retained to provide services during any future: site observations, design, implementation activities, construction and/or property development/redevelopment. This will allow us the opportunity to: i) observe conditions and compliance with our design concepts and opinions; ii) allow for changes in the event that conditions are other than anticipated; iii) provide modifications to our design; and iv) assess the consequences of changes in technologies and/or regulations. Proactive by Design APPENDIX B RECORD DRAWINGS and Existing Flood Level Information Proactive by Design APPENDIX C 3D LEAPFROG MODEL SCREENSHOTS 3D digital elevation model for Mill River levee Figure C1 -Leapfrog 3D model integrating subsurface information for Mill River levee Historic soil profile excerpts from 1945 O&M manual GZA borings MR-1 to MR-8 Figure C2 -3D geological model for Mill River Levee based on subsurface information 3D geological model for Mill River levee Figure C3 -Soil profile for cross-sections at specified locations of Mill River Levee Section near Sta.6+00 Section near Sta.9+00 Section near Sta.22+00 Section near Sta.20+00 Section near Sta.18+00 Proactive by Design APPENDIX D Model Parameters GZA Engineers and JOB GeoEnvironmental, Inc.Scientists SHEET NO.1 OF 249 Vanderbilt Avenue CALCULATED BY YY DATE Norwood, MA 02062 CHECKED BY JGD DATE 781‐278‐3700 SCALE FAX 781‐278‐5701 http://www.gza.com Objective:This cover sheet summarizes the soil hydraulic conductivity and strength parameters determined for seepage and slope stability analyses of Connecticut River (CT) Levee and Mill River (MR) Levee in Northampton, MA Method: ‐ Estimate hydraulic conductivity for granular soil samples from test boring using laboratory data (grain size & USCS classification) and typical values of similar materials. See the appended correlation spreadsheets for more details 1) "Correlation of SPT‐N Values to phi Worksheet ‐ Connecticut River Levee" 2) "Correlation of SPT‐N Values to phi Worksheet ‐ Mill River Levee" ‐ Estimate friction angle for granular soils from test borings and typical values of similar materials. See the appended correlation spreadsheets for more details 3) "Empirical Correlations for Hydraulic Conductivity ‐ Connecticut River Levee" 4) "Empirical Correlations for Hydraulic Conductivity ‐ Mill River Levee" ‐ Estimate parameters for the varved clay based on the published value in the literature Subsurface Profile: ‐ The sub‐surface profiles for CT Levee and MR Levee was developed by using the following information: 1) Boring log information from GZA Borings CT1 to CT14 on CT Levee and Boring logs from GZA Boring MR1 to MR8 on MR Levee 2) Record Drawing ”Northampton Dike ‐ Subsurface Profile ‐ Conn. River Dike ‐ Operation and Maintenance Manual“ by Corps. of Engineers, U.S. Army, Providence, RI, dated April 1945, Plates VIII A & XV A 3) Record Drawing ”Northampton Dike ‐ Embankment Details ‐ Conn. River Dike ‐ Operation and Maintenance Manual“ by Corps. of Engineers, U.S. Army, Providence, RI, dated April 1945, Plate VIII & XIII 4) Design Report "Connecticut River Flood Control Project‐ Northampton Mass Connecticut & Mill Rivers Analysis of Design for Local Protection Works ‐ Item No.2 & No.3 " by Corps of Engineers, US Army dated April 1939 ‐ The Seequent 3D geological modeling software ‐ Leapfrog was then used to model the topography and the soil strata for the cross‐sections at a series of selected locations along the levee. ‐ The developed profile for each section was imported into the Seequent Geostudio program for seepage and stability analyses ‐ Three representative sections (two for CT Levee and one for MR levee) and the associated soil layers are shown below as example. ‐ The material parameters determined for the soil layers identified in the sections below are summarized in Table 1. Fig.1 Section Sta. 10+00 of CT‐ Levee Fig.2 Section Sta. 47+00 of CT‐ Levee Fig.3 Section Sta. 20+00 of MR Levee N/A 174343.00 Northampton Levee Certification Support 2 5/30/2020 6/1/2020 Existing_Embank Top Soil Pervious Fill Impervious FillRandom_Fill Sand Varved_Clay Top Soil Pervious Fill Impervious Fill Existing_Fill Random_Fill Silt_and_Clay Sand Varved_Clay Existing_Fill Sand Varved_Clay Weathered_Sandstone riprap Impervious Fill Random_Fill Existing Fill Random_Fill Impervious Core Top Soil GZA Engineers and JOB GeoEnvironmental, Inc.Scientists SHEET NO.2 OF One Edgewater Drive CALCULATED BY YY DATE Norwood, MA 02062 CHECKED BY JGD DATE 781‐278‐3700 SCALE FAX 781‐278‐5701 http://www.gza.com Table 1. Summary of Material Properties: ft/s cm/s 120 0 31 100 10 1 4.2E‐07 1.3E‐05 120 0 30 1 4.3E‐04 1.3E‐02 120 0 32 200 10 1 4.2E‐07 1.3E‐05 120 0 32 1 1.6E‐04 4.8E‐03 125 0 34 500 11 1 1.5E‐06 4.6E‐05 145 0 40 1 1.0E‐01 3.0E+00 110 0 28 300 10 1 5.9E‐08 1.8E‐06 110 0 28 300 10 1 2.9E‐08 8.9E‐07 120 0 30 1 3.5E‐04 1.1E‐02 110 0.143 2.0E‐07 6.1E‐06 120 0 32 800 0 1 7.3E‐10 2.2E‐08 110 0.143 2.0E‐07 6.1E‐06 130 0 45 1000 0 1 7.8E‐09 2.4E‐07 Note (1) ‐ Unit weight values based on typical values for similar materials (2) ‐ Permeability values was estimated based grain size correlations and typical values for similar materials (3) ‐ Drained strength values based on correlations from SPT‐N testing and also typical values for similar materials (4) ‐ Undrained strength for Varved clay based on the lower bound of the range published by DeGroot & Lutenegger (2002). (5) ‐ Unit weight, Effective Strength, K‐ratio, and permeability values based on typical values published by DeGroot & Lutenegger (2002). Attachments: Attachment Excerpts of literature for material parameters of the varved clay Varved Clay su = 500psf Existing Fill (overlying) Top Soil Impervious Fill K Ratio (kv/kh) Impervious Fill Cohesion (psf) Pervious Fill Same as in CT Levee Same as in CT Levee Same as in CT Levee Sand Silt & Clay Connecticut River Levee Top Soil Saturated Horizontal Hydraulic conductivity, ksat Notes Friction Angle, (°) 174343.00 Northampton Levee Certification Support 5/30/2020 6/1/2020 N/A 2 Mill River Levee Total Unit Weight, t (pcf) Strength Parameters Cohesion, c' (psf) Strength (Drawdown) Riprap Existing Embankment Strata Random Fill Existing Fill same as effective strength same as effective strength su increases with depth su = 500psf Friction Angle, '(°) Same as in CT Levee Same as in CT Levee Same as in CT Levee su increases with depth (1),(2),(3) Varved Clay (4),(5) Riprap same as effective strength same as effective strength Weathered Bedrock (1),(2),(3) Selected Impervious Fill (Imperv. Core) Random Fill Sand (1),(2),(3) (4),(5) Attachment Excerpts of literature for material parameters of the varved clay Figure V1. Horizontal Hydraulic conductivity for varved clay (DeGroot & Lunenegger 2002) Selected kh=6E‐6cm/sec = 2E‐7ft/sec Figure V2. Undrained strength distribution for Varved clay suggested by Ladd and Wissa (1970) Figure V3. Table of undrained strength values for Varved clay suggested by Ladd and Wissa (1970) Selected undrained strength profile for Varved Clay CT Levee Elevation Depth [ft] su [ksf] 90 42 540 80 52 600 70 62 660 60 72 705 50 82 755 40 92 800 MR Levee Elevation Depth [ft] su [ksf] 108 32 480 98 42 540 88 52 600 20 30 40 50 60 70 80 90 100 400 500 600 700 800 900 Depth below levee crest [ft]Selected Undrained Strength su for Varved Clay [ksf] CT MR Proactive by Design APPENDIX E OUTPUT FOR SEEPAGE AND SLOPE STABILITY ANALYSES GZA GeoEnvironmental, Inc. 249 Vanderbilt Avenue JOB Norwood, MA 02062 SHEET NO.1 OF 781‐278‐3700 CALCULATED BY CJT/YY DATE FAX 781‐278‐5701 CHECKED BY JGD DATE http://www.gza.com SCALE Objective:Evaluate seepage and slope stability of Northampton Mill River Levee at the following Cross‐Sections 6+00, 9+00, 18+00, 20+00, 22+00 Method: 1) Develop typical cross section of levee at selected Stations 6+00, 9+00, 18+00, 20+00, 22+00 2) Determine material parameters from test borings and typical values of similar materials. 3) Calculate location of phreatic surface within levee for different conditions, using SEEP/W. Calculate exit gradient to evaluate piping failure (where applicable). Case #1 ‐ Steady‐state seepage at 100‐yr Flood Case #2 Steady‐state seepage under normal condition 4) Using pore water data from SEEP/W, calculate factors of safety against slope failure for the following load cases defined by requirements of EM 1110‐2‐1913, Section 6‐7302. Steady‐state factors of safety calculated for both riverside and landside slopes using Spencer method. Rapid drawdown factor of safety calculated using USACE 3‐stage method. Case #3 (A,B) ‐ Steady‐state seepage at 100‐yr Flood Case #3 (C) ‐ Rapid Drawdown from 100 yr Flood (Riverside only) Case #4 (A,B) ‐ Steady‐state seepage at Normal Pool Case #5 (A,B) ‐ Seismic (pseudostatic, 0.12g horizontal acceleration) 5) The above load cases conservatively ignored the toe drain at the downstream face, whose current functionality was not verified. Subsurface Information: ‐ Test borings MR‐1 through MR‐8 and Exploration Location Plan by GZA (December 2018‐ January 2019) ‐ "Analysis of Design and Local Protection Works Fiscal Year 1939 Section, Item N.2 Contract ‐ STA. 0 to High Ground Over Railroad And Highway" War Dept., Corps. of Engineers, U.S. Army, U.S. Engineer Office, Providence, RI, dated April 1939 ‐ "Analysis of Design and Local Protection Works Item N.3 Diversion Canal, Oxbow Bridge and Dike Along East Bank Mill River Part Contract, Part Hired Labor" War Dept., Corps. of Engineers, U.S. Army, U.S. Engineer Office, Providence, RI, dated April 1939 ‐ "Operation and Maintenance Manual for Flood Protection System Northampton, Massachusetts." War Dept., Corps. of Engineers U.S. Army, U.S. Engineer Office, Providence, RI, dated April 1945 Assumptions: ‐ 0.12g Horizontal acceleration for pseudostatic seismic analysis calculated as 2/3 of the PGA for a Site Class E, per USGS Seismic Hazard Maps. ‐ Soil strata interpreted from available test boring data and design drawings, actual configuration may vary. Material Properties: ft/s cm/s 120 0 31 100 10 1 4.20E‐07 1.3E‐05 145 040 1 1.00E‐01 3.0E+00 120 0 30 1 4.3E‐04 1.3E‐02 120 0 32 200 10 1 4.2E‐07 1.3E‐05 120 0 32 800 0 1 7.3E‐10 2.2E‐08 125 0 34 500 11 1 1.5E‐06 4.6E‐05 120 0 30 1 3.5E‐04 1.1E‐02 110 0.143 2.0E‐07 6.1E‐06 130 0 45 1000 0 1 7.8E‐09 2.4E‐07 (1) ‐ Unit weight values based on typical values for similar materials (2) ‐ Permeability values based grain size correlations (3) ‐ Drained strength values based on correlations from SPT‐N testing, total strength values are estimated with typical values (4) ‐ Unit weight, Effective Strength, K‐ratio, and permeability values based on typical values for CVVC published by DeGroot & Lutenegger. (5) ‐ Permeability values based on results of Army Corps design analysis Analysis Results: 6+00 9+00 18+00 20+00 22+00 0.5 <0.1 <0.1 <0.1 <0.1 <0.1 Y 0.5 <0.1 <0.1 <0.1 <0.1 <0.1 Y ‐ Note: Factor of safety values less than recommended values are shown in italics (1) ‐ Flow and exit gradient estimated from results of SEEP/W analysis at landside face of the levee, was denoted "<0.1" when the value is negligible (2) ‐ Limiting gradient per requirements of US Army Corps Technical Letter ETL 1110‐2‐569 "DESIGN GUIDANCE FOR LEVEE UNDERSEEPAGE" 2 Normal Conditions 12/10/2020 12/16/2020 (1),(2),(3) (1),(2),(3) 1 100yr Flood Same as effective strength Same as effective strength Same as effective strength Cohesion, c (psf) 174343.00 Northampton Levee Certification Support Saturated Horizontal Permeability, ksat Limiting Gradient(2) Exit Gradient, ie(1) OK?Station N/A Notes 2 (4),(5) Sand Selected Impervious Fill (Imperv. core) Su increases with depth Top Soil Impervious Blanket Fill Varved Clay (1),(3),(6) su = 500psf (1),(2),(3) (1),(2),(3) (1),(2),(3) (1),(2),(3) Strength (Drawdown) K Ratio (kv/kh)Friction Angle, (°) Strength Parameters Cohesion, c' (psf) Rip Rap Strata Random Fill Overlying Fill Friction Angle, '(°) Total Unit Weight, t (pcf) Weathered bedrock (1),(2),(3) SEEPAGE ANALYSIS RESULTS ‐ EXISTING CONDITIONS Case River Elevation GZA GeoEnvironmental, Inc. 249 Vanderbilt Avenue JOB Norwood, MA 02062 SHEET NO.2 OF 2 781‐278‐3700 CALCULATED BY CJT/YY DATE FAX 781‐278‐5701 CHECKED BY JGD DATE http://www.gza.com SCALE Analysis Results Cont'd: 6+00 9+00 18+00 20+00 22+00 1.5 1.6 1.8 1.9 1.6 1.7 1.6 2.1 2.1 2.2 1.5 1.5 2.1 2.1 1.8 1.7 1.5 1.5 1.5 2.7 1.2 1.2 1.4 1.3 1.4 1.2 1.0 1.0 0.9 1.3 ‐ Note: Factor of safety values less than recommended values are shown in italics (1) ‐ FS = 1.0 applies to flood levels unlikely to persist for long periods prior to drawdown, FS = 1.2 applies to levels likely to persist for long periods prior to drawdown. (2) ‐ Earthquake loading applied as a lateral load using seismic coefficient of 0.12g (3) ‐ Factor of safety not provided in EM 1110‐2‐1913 ‐ Refer to Attached SLOPE/W slope stability analysis graphical results 100‐year Flood (Steady State)U/S 1.4 Levee Face U/S Factor of Safety StationMinimum Comments / Notes 1.2 1.4 5 (A,B)Seismic(2) (Pseudostatic, normal conditions) D/S 1.0(3) Normal Conditions D/S 1.4 SLOPE STABILITY ANALYSIS RESULTS ‐ EXISTING CONDITIONS 1.4 2.5 4 (A,B) Loading Condition U/S 3 (C) Load Case D/S N/A 3 (A,B) 1.4 Sudden Drawdown ‐ 100‐year Flood U/S 1.0 ‐ 1.2(1) 174343.00 Northampton Levee Certification Support 12/10/2020 12/16/2020 Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Top SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09LandsideRiverside100yr Flood Water Level = 134'Groundwater Level = 129'XY Gradient < 0.14.2e-071.5e-060.14.2e-07Water Flow Rate = 1E-5 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Seepage Analysis100 Year Flood Level1-1 Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Top SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09LandsideRiversideNormal Condition Elevation = 118'Groundwater Level = 118'XY Gradient < 0.14.2e-071.5e-060.14.2e-07Water Flow Rate = 1E-14 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Seepage AnalysisNormal Conditions1-2 1.5Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45LandsideRiverside100yr Flood Water Level = 134'Groundwater Level = 129'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+001-3ADownstream Slope Stability500 Year Flood Level 1.7Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45LandsideRiverside100yr Flood Water Level = 134'Groundwater Level = 129'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Upstream Slope Stability100 Year Flood Level1-3B 1.2Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModel Unit Weight(pcf)Effective Cohesion(psf)EffectiveFriction Angle (°)CohesionR (psf)Phi R (°)Impervious Fill Mohr-Coulomb 120 0 32 200 10Overlying FillMohr-Coulomb 120 0 30 0.1 29Random_FillMohr-Coulomb 125 0 34 500 11riprapMohr-Coulomb 145 0 40 1 39SandMohr-Coulomb 120 0 30 1 29Top SoilMohr-Coulomb 120 0 31 100 10Varved_Clay_Su500psf Mohr-Coulomb 110 500 0 500 0Weathered_Sandstone Mohr-Coulomb 130 0 45 1,000 0LandsideRiversideGroundwater Level = 129'100yr Flood Water Level = 134'Normal Condition Elevation = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Rapid Drawdown100 Year Flood Level1-3C 1.5Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45LandsideRiversideNormal Condition Elevation = 118'Groundwater Level = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Downstream Slope StabilityNormal Conditions1-4A 1.7Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45LandsideRiversideNormal Condition Elevation = 118'Groundwater Level = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Upstream Slope StabilityNormal Conditions1-4B 1.2Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45LandsideRiversideNormal Condition Elevation = 118'Groundwater Level = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Downstream Slope Stability - SeismicNormal Conditions1-5A 1.2Distance [ft]020406080100120140160180200220240260280300Elevation (NAVD) [ft]90100110120130140150Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45LandsideRiversideNormal Condition Elevation = 118'Groundwater Level = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.6+00Upstream Slope Stability - SeismicNormal Conditions1-5B Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Top SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09100yr Flood Water Level = 134'Groundwater Level = 129'XY Gradient < 0.14.2e-071.5e-060.14.2e-07Water Flow Rate = 1E-5 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-1Seepage Analysis100 Year Flood Level Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Top SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09Groundwater Level = 118'XY Gradient < 0.1Normal Condition Elevation = 118'4.2e-071.5e-060.14.2e-07Water Flow Rate = 1E-17 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-2Seepage AnalysisNormal Conditions 1.6Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45100yr Flood Water Level = 134'Groundwater Level = 129'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-3ADownstream Slope Stability100 Year Flood Level 1.6Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45100yr Flood Water Level = 134'Groundwater Level = 129'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-3BUpstream Slope Stability100 Year Flood Level 1.4Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameModel Unit Weight(pcf)Effective Cohesion(psf)EffectiveFriction Angle (°)CohesionR (psf)Phi R (°)Impervious Fill Mohr-Coulomb 120 0 32 200 10Overlying FillMohr-Coulomb 120 0 30 0.1 29Random_FillMohr-Coulomb 125 0 34 500 11riprapMohr-Coulomb 145 0 40 1 39SandMohr-Coulomb 120 0 30 1 29Top SoilMohr-Coulomb 120 0 31 100 10Varved_Clay_Su500psf Mohr-Coulomb 110 500 0 500 0Weathered_Sandstone Mohr-Coulomb 130 0 45 1,000 0100yr Flood Water Level = 134'Groundwater Level = 129'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-3CRapid Drawdown100 Year Flood Level 1.5Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 118'Normal Condition Elevation = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-4ADownstream Slope StabilityNormal Conditions 1.5Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 118'Normal Condition Elevation = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-4BUpstream Slope StabilityNormal Conditions 1.2Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideGroundwater Level = 118'Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Normal Condition Elevation = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-5ADownstream Slope Stability - SeismicNormal Conditions 1.0Distance [ft]020406080100120140160180200220240260280300Elevation (NAVE) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 118'Normal Condition Elevation = 118'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.9+002-5BUpstream Slope Stability - SeismicNormal Conditions Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Selected Impervious FillTop SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09Groundwater Level = 123'100yr Flood Water Level = 131'XY Gradient < 0.14.2e-071.5e-060.17.3e-104.2e-07Water Flow Rate = 1E-5 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-1Seepage Analysis100 Year Flood Level Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Selected Impervious FillTop SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09Groundwater Level = 115'XY Gradient < 0.1Normal Condition Elevation = 115'4.2e-071.5e-060.17.3e-104.2e-07Water Flow Rate = 1E-17 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-2Seepage AnalysisNormal Conditions 1.8Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 123'100yr Flood Water Level = 131'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-3ADownstream Slope Stability100 Year Flood Level 2.1Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 123'100yr Flood Water Level = 131'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-3BUpstream Slope Stability100 Year Flood Level 1.4Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModel Unit Weight(pcf)Effective Cohesion(psf)EffectiveFriction Angle (°)CohesionR (psf)Phi R (°)Impervious Fill Mohr-Coulomb 120 0 32 200 10Overlying FillMohr-Coulomb 120 0 30 0.1 29Random_FillMohr-Coulomb 125 0 34 500 11riprapMohr-Coulomb 145 0 40 1 39SandMohr-Coulomb 120 0 30 1 29Selected Impervious FillMohr-Coulomb 120 0 30 800 0Top SoilMohr-Coulomb 120 0 31 100 10Varved_Clay_Su500psf Mohr-Coulomb 110 500 0 500 0Weathered_Sandstone Mohr-Coulomb 130 0 45 1,000 0Groundwater Level = 123'100yr Flood Water Level = 131'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-3CRapid Drawdown100 Year Flood Level 2.1Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-4ADownstream Slope StabilityNormal Conditions 1.5Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-4BUpstream Slope StabilityNormal Conditions 1.4Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-5ADownstream Slope Stability - SeismicNormal Conditions 1.0Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260Elevation (NAVD) [ft]90100110120130140150160RiversideLandsideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.18+003-5BUpstream Slope Stability - SeismicNormal Conditions Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Selected Impervious FillTop SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09100yr Flood Water Level = 131'Groundwater Level = 125'XY Gradient < 0.14.2e-071.5e-060.17.3e-104.2e-07Water Flow Rate = 1E-8 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-1Seepage Analysis100 Year Flood Level Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameSat Kx (ft/sec)Impervious FillOverlying Fill0.00043Random_FillriprapSand0.00035Selected Impervious FillTop SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09Groundwater Level = 115'XY Gradient < 0.1Normal Condition Elevation = 115'4.2e-071.5e-060.17.3e-104.2e-07Water Flow Rate = 1E-17 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-2Seepage AnalysisNormal Conditions 1.9Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45100yr Flood Water Level = 131'Groundwater Level = 125'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-3ADownstream Slope Stability100 Year Flood Level 2.1Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 125'100yr Flood Water Level = 131'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-3BUpstream Slope Stability100 Year Flood Level 1.4Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModel Unit Weight(pcf)Effective Cohesion(psf)EffectiveFriction Angle (°)CohesionR (psf)Phi R (°)PiezometricLine After DrawdownImpervious Fill Mohr-Coulomb 120 0 32 200 10 2Overlying FillMohr-Coulomb 120 0 30 0.1 29 2Random_FillMohr-Coulomb 125 0 34 500 11 2riprapMohr-Coulomb 145 0 40 1 39 2SandMohr-Coulomb 120 0 30 1 29 2Selected Impervious FillMohr-Coulomb 120 0 30 800 0 2Top SoilMohr-Coulomb 120 0 31 100 10 2Varved_Clay_Su500psf Mohr-Coulomb 110 500 0 500 0 2Weathered_Sandstone Mohr-Coulomb 130 0 45 1,000 0 2Groundwater Level = 125'100yr Flood Water Level = 131'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-3CRapid Drawdown100 Year Flood Level 2.1Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-4ADownstream Slope StabilityNormal Conditions 1.5Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-4BUpstream Slope StabilityNormal Conditions 1.3Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-5ADownstream Slope Stability - SeismicNormal Conditions 0.9Distance [ft]020406080100120140160180200220240260Elevation (NAVD) [ft]90100110120130140150160LandsideRiversideColor NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Impervious Fill Mohr-Coulomb 1200 32Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45Groundwater Level = 115'Normal Condition Elevation = 115'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.20+004-5BUpstream Slope Stability - SeismicNormal Conditions Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameSat Kx (ft/sec)Overlying Fill0.00043Random_FillriprapSand0.00035Selected Impervious FillTop SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09RiversideLandside100yr Flood Water Level = 131'Groundwater Level = 131'XY Gradient < 0.11.5e-060.17.3e-104.2e-07Water Flow Rate = 1E-9 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-1Seepage Analysis100 Year Flood Level Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameSat Kx (ft/sec)Overlying Fill0.00043Random_FillriprapSand0.00035Selected Impervious FillTop SoilVarved_Clay2e-07Weathered_Sandstone 7.8e-09RiversideLandsideGroundwater Level = 126'XY Gradient < 0.1Normal Condition Elevation = 126'1.5e-060.17.3e-104.2e-07Water Flow Rate = 1E-17 ft^3/secCity of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-2Seepage AnalysisNormal Conditions 1.6Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45RiversideLandside100yr Flood Water Level = 131'Groundwater Level = 131'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-3ADownstream Slope Stability100 Year Flood Level 2.2Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45RiversideLandside100yr Flood Water Level = 131'Groundwater Level = 131'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-3BUpstream Slope Stability100 Year Flood Level 2.5Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModel Unit Weight(pcf)Effective Cohesion(psf)EffectiveFriction Angle (°)CohesionR (psf)Phi R (°)Overlying FillMohr-Coulomb 120 0 30 0.1 29Random_FillMohr-Coulomb 125 0 34 500 11riprapMohr-Coulomb 145 0 40 1 39SandMohr-Coulomb 120 0 30 1 29Selected Impervious FillMohr-Coulomb 120 0 30 800 0Top SoilMohr-Coulomb 120 0 31 100 10Varved_Clay_Su500psf Mohr-Coulomb 110 500 0 500 0Weathered_Sandstone Mohr-Coulomb 130 0 45 1,000 0RiversideLandside100yr Flood Water Level = 131'Groundwater Level = 131'Normal Condition Elevation = 126'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-3CRapid Drawdown100 Year Flood Level 1.8Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45RiversideLandsideGroundwater Level = 126'Normal Condition Elevation = 126'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-4ADownstream Slope StabilityNormal Conditions 2.7Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45RiversideLandsideGroundwater Level = 126'Normal Condition Elevation = 126'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-4BUpstream Slope StabilityNormal Conditions 1.4Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45RiversideLandsideGroundwater Level = 126'Normal Condition Elevation = 126'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-5ADownstream Slope Stability - SeismicNormal Conditions 1.3Distance [ft]0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220Elevation (NAVD) [ft]90100110120130140150160Color NameModelUnit Weight(pcf)CohesionFnEffective Cohesion(psf)EffectiveFriction Angle (°)Overlying FillMohr-Coulomb 1200 30Random_FillMohr-Coulomb 1250 34riprapMohr-Coulomb 1450 40SandMohr-Coulomb 1200 30Selected Impervious FillMohr-Coulomb 120 0 30Top SoilMohr-Coulomb 1200 31Varved_ClaySpatial Mohr-Coulomb 110 Su (Depth)0Weathered_Sandstone Mohr-Coulomb 1300 45RiversideLandsideGroundwater Level = 126'Normal Condition Elevation = 126'City of Northampton Department of Public WorksPREPARED FOR:PREPARED BY:GZA GeoEnviornmental, Inc.Engineers and Scientistswww.gza.comPROJ MGR: CLBDESIGNED BY: CJTREVIEWED BY: CLBDRAWN BY: CJTDATE:PROJECT NO.:FIGURE01.0174343.0012/10/2020Mill River Levee Analysis Sta.22+005-5BUpstream Slope Stability - SeismicNormal Conditions