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Final Northampton Test Pit and Soil Infiltration Report 022820 Copyright  2020 GZA GeoEnvironmental, Inc. An Equal Opportunity Employer M/F/V/H Via Email February 28, 2020 File No. 01.0171439.10 Mr. Haris Awal, P.E. Parsons 100 High Street Boston, Massachusetts 02110 Re: Test Pit and Soil Infiltration Results Report Bio-Retention Ponds & Mast Arm Foundations I-91 over Route 5 and Boston & Maine Railroad and I-91 over Hockanum Road Bridge Nos. N-19-059 and N-19-060, MassDOT Project No. 606552 Northampton, Massachusetts Dear Haris: GZA GeoEnvironmental, Inc. (GZA) is pleased to submit this revised letter summarizing the soil evaluation conducted at the proposed bioretention pond locations for the replacement of the I-91 Bridge over Route 5 and B&M Railroad Bridge (Bridge No. N- 19-059) and the replacement of the I-91 Bridge over Hockanum Road (Bridge No. N- 19-060). The objective of this work was to conduct a Stage 2 Soil Investigation for two proposed bioretention ponds for the purpose of evaluating infiltration rates of soils at the two bioretention pond locations. This letter is subject to the limitations contained in Appendix A. BACKGROUND The project proposes two bioretention ponds identified as the “I-91 Bioretention Pond” and the “Route 5 Bioretention Pond” in Northampton, MA (“Site”). Our understanding of the project and the proposed location of bioretention ponds is based on the plan set titled “Bridge Replacements N-19-059 and N-19-060 over U.S. Route 5 and B&M RR I-91 over Hockanum Road in Northampton County, MA,” prepared by Parsons dated October 16, 2019. Based on correspondence with Parsons, GZA understands that a Stage 2 Soil Investigation, as described in the 2008 Massachusetts Stormwater Handbook (Volume 3) is required at the I-91 and Route 5 bioretention ponds to support design review by MassDOT, to document compliance with the Massachusetts Stormwater Standards and to support engineering design of the ponds by Parsons. February 28, 2020 01.0171439.10 Test Pit and Soil Infiltration Results Report Page | 2 Existing Conditions The project site and bioretention ponds are proposed to be located in the interior of the existing Ramp B at the intersection of Route 5 and I-91 in Northampton (see Figure 1 Site Locus). The Site is bordered by I-91 northbound to the north and extends approximately 803 feet south to the Ramp B and Route 5 intersection. The Site is bordered to east by Route 5, and to the south and west by Ramp B. The area is currently maintained as a mix of grass and low growing vegetation. Vegetated wetland systems occur on Site and are shown on the plans referenced above. Wetland 2A directly borders the western side of the proposed Route 5 Bioretention Pond. Proposed Development The project consists of replacing two existing bridges on I-91 which includes the construction of two bioretention ponds to support compliance with the 2008 Massachusetts Stormwater Standards. The I-91 Bioretention Pond (i.e. I-91 Pond) is proposed in the northwestern portion of the Site adjacent to the I-91 northbound lane. The proposed I-91 Pond will accept stormwater runoff from four separate outflow pipes as depicted on the plans referenced above. An overflow spillway approximately 20 feet in length is proposed in the northeastern portion of the I-91 Pond. The Route 5 Bioretention Pond (i.e. Route 5 Pond) is proposed along the eastern edge of the Site adjacent to Route 5. The proposed Route 5 Pond will contain a sediment forebay in the northern portion of the Pond. An overflow spillway approximately 20 feet in length will be located in the southern portion of the Route 5 Pond. Stormwater Discharge and Area Design Requirements The 2008 MassDEP storm water regulations require the following information be determined for performing Stage 2 Soil Investigation regulated by the Wetlands Protection Act (310CMR 10.00) as part of the design: 1. Soil type and textural analysis; 2. Depth to estimated seasonal high water table; and 3. Infiltration rate of the underlying soils. Soil textural analysis, or relative composition of sand, silt and clay in the soil, is determined using procedures described in the USDA, NRCS, 2007 National Soil Survey Handbook, Section 618, Exhibit 8. The depth to estimated seasonal high water table is determined by identifying redoximorphic features (soil mottles) within the soil profile. The infiltration rate may be determined by using designated infiltration rates provided in the regulations described as the “Static” or “Simple Dynamic” method. These methods provide infiltration rates based on soil textural analysis and using the rates associated with the slowest of the Hydrologic Soil Groups determined to exist at the point where recharge is proposed. Infiltration rate may also be determined using the “Dynamic Field” method which requires field evaluation to determined saturated hydraulic conductivity rates at the actual location and soil layer where recharge is proposed. SUBSURFACE EXPLORATIONS A total of nine test pits were excavated by New England Boring Contractors (NEBC) on February 18, 2020 using a small rubber-tired excavator, including five test pits in the proposed I-91 Pond and four test pits in the proposed February 28, 2020 01.0171439.10 Test Pit and Soil Infiltration Results Report Page | 3 Route 5 Pond (See Figures 2 and 2A). The location, number, and depth of test pits were selected based on the requirements of the 2008 Stormwater Handbook. The test pits were excavated to depths varying between approximately six feet to nine feet below ground surface based on observed variation of soil conditions. Upon completion, the test pits were backfilled with the excavated material and tamped with the back of the excavator bucket. Locations of the explorations were made by tape measurements from nearby site features. Test Pit logs and photographs of the test pits prepared by GZA are included in Appendices B and C, respectively. GZA personnel coordinated and observed the test pits. A GZA MassDEP Approved Soil Evaluator reviewed the soil samples and classified the soil using the United States Department of Agriculture (USDA) textural analysis methodology. The depth to seasonal high water table and any evidence of redoximorphic features indicative of fluctuating seasonal high water tables were noted on the logs where such conditions were encountered. Soil infiltration testing at the I-91 Pond and Route 5 Pond was proposed to supplement the soil textural analysis using a Compact Constant Head Permeator (i.e. an Amoozemeter) to assess saturated hydraulic conductivity. However, the equipment does not function well when ambient temperatures are near freezing. During field work, the temperatures were such that the unit did not function. SUMMARY OF RESULTS Subsurface Conditions Subsurface conditions observed in the explorations in the Route 5 Pond generally consist of topsoil overlying natural granular soils and massive floodplain alluvial soils. Fill material was encountered in Test Pit Nos. 1-4 within the proposed location of the Route 5 Pond. The depth to groundwater was not encountered at the test pit locations. Surface conditions observed in the explorations in the I-91 Pond generally consist of topsoil overlying natural silt loam and clayey soils. No fill material was encountered in Test Pit Nos. 5-9 which were excavated within the proposed location of the I-91 Pond. The depth to groundwater was not encountered at the test pit locations. Refer to the test pit logs in Appendix B for specific information at each exploration. NRCS Hydrologic Soil Group and Infiltration Rate The Natural Resources Conservation Service (NRCS) Hydrologic Soil Group and corresponding Infiltration Rate (Rawls Rates) for the soil encountered in the test pits and test borings at the proposed BMP areas are provided in Table 1. In Test Pits #1, 2, 3, 4, 7, and 9, the NRCS Hydrologic Soil Group classifications ranged from Hydrologic Group A to C, based on the USDA Soil Textural Class presented in Table 2.3.3 of the MassDEP Stormwater Management Regulations dated February 2008 (see Table 1). However, the MassDEP Stormwater Management Regulations Volume 2, Chapter 2 assign hydrologic soil classifications of ‘D’ where the bottom of an infiltration basin does not meet the minimum two foot vertical clearance to the top of the seasonal high water table. However, as previously mentioned, the observed seasonal high water tables are due to perched water table conditions as a result of clay and silt loam soils, and are not a result of groundwater influence. As a result, a hydrologic classification of ‘D’ based solely on the seasonal high water table may not be appropriate, unless the textural analysis also indicates a classification of ‘D’ (e.g. at the Route 5 Pond). February 28, 2020 01.0171439.10 Test Pit and Soil Infiltration Results Report Page | 4 In Test Pits #5, 6, and 8, the NRCS Hydrologic Soil Group classifications were determined based on the USDA Soil Textural Class presented in Table 2.3.3 of the MassDEP Stormwater Management Regulations. These test pits were dominated by silt clay soils, and are therefore classified as Hydrologic Soil Group D regardless of the distance to the seasonal high water table. The infiltration rates (i.e. Rawls rates) were determined based on the USDA Soil Textural Class presented in Table 2.3.3 of the MassDEP Stormwater Management Regulations. In the Route 5 Pond, Rawls infiltration rates range from 0.27 in/hour to 2.41 in/hour, with an average of 1.34 in/hour. The NRCS has mapped the Route 5 Pond Area as Hadley-Winooksi, with infiltration rates assigned by NRCS of 0.6 in/hour to 6.0 in/hour. In GZA’s opinion, given that the lowest rate reported by NRCS falls within the predicted Rawls rates, utilizing an infiltration rate of 0.6 in/hour is appropriate. In the I-91 Pond, Rawls infiltration rates range from 0.04 in/hour to 2.41 in/hour, with an average of 0.13 in/hour. The rates in the I-91 Pond are lower than what is reported by NRCS for the soil type (Hadley-Winooksi soils). This is expected to occur where inclusions of other soils are present in the soil unit. Based on the test pit evaluation completed by GZA, the Route I-91 Pond consists of poorly drained soil, which is an inclusion of a separate soil unit with lower infiltration rates. Given that two of the three test pits located within the proposed basin where infiltration is proposed to occur, including Test Pit #6 and #8, were designated an infiltration rate of 0.04 in/hour, it is GZA’s opinion that a recommended infiltration rate of 0.04 in/hour is appropriate in this basin (see Table 1). Estimated Seasonal High Water Table Seasonal high water table depths are typically estimated based on soil morphology and the presence of redoximorphic features (soil mottles) indicative of a fluctuating seasonal high water table. However, it was noted by GZA that observed redoximorphic features and estimated seasonal high water tables were a result of surface water influence due to a perched water table over clay soils, rather than by groundwater influence. Soil mottles were observed in each of the nine test pits. Soil mottles were observed between 3 and 4 feet beneath the ground surface in the Route 5 Pond test pits. Soil mottles were observed at a more shallow depth between about 0.7 to 1.5 feet beneath the ground surface in the I-91 Pond test pits. There were no observable water tables during test pit explorations. REFERENCE DOCUMENTS The following documents were used as part of the Stage 2 Soil Investigation and to prepare this summary letter. • Massachusetts Department of Environmental Protection, Massachusetts Stormwater Handbook, Volume 2, Chapter 2, “Stormwater Best Management Practices,” February 2008. • Massachusetts Department of Environmental Protection, Massachusetts Stormwater Handbook, Volume 3, Chapter 1, “Documenting Compliance,” February 2008. CONCLUSIONS We understand that the findings of the exploration program will be used by Parsons for final design of the bioretention ponds. We anticipate that some of the proposed storm water discharge areas in the Route 5 Pond and the I-91 Pond will need to be modified based on the findings of the recent explorations due to presence of silt loam and clay soils and to provide adequate vertical distance between the estimated seasonal high water table and the bottom of the storm water discharge areas. February 28, 2020 01.0171439.10 Test Pit and Soil Infiltration Results Report Page | 5 It should be noted that subsurface conditions at the storm water discharge areas may vary from those encountered in the test pits discussed herein. In addition, fluctuations in the level of surface water may occur due to variations in season, rainfall, and other factors different than those existing at the time the explorations were made. RECOMMENDATIONS GZA recommends the following to support the design of the Route 5 and I-91 infiltration ponds: • Based on the test pit evaluation, estimated seasonal high water tables observed in the test pits are a result of a perched water table, and not by groundwater influence. Therefore, GZA recommends the NRCS Hydrologic Soil Group classifications based on the USDA Soil Textural Class, and not on the nearness to the seasonal high water table, are appropriate to consider at the Site for estimating infiltration rates of the bioretention ponds. • Given the presence of a perched water table, GZA recommends that Parsons evaluate the feasibility of removing clay soil layers in the I-91 Pond and restrictive silt loam soil layers in the Route 5 Pond to expose soils with more suitable textures for infiltration, and backfilling with granular soils that allow for faster infiltration rates. • As an alternate to, or in addition to removal of the clay and silt loam soils, Parsons should consider installation of underdrains beneath the bioretention soil layer to improve the function of the ponds where low permeability soils are present, particularly for the I-91 Pond where the lower infiltration soils are prevalent. The underdrains should be constructed within crushed stone and wrapped all-around with non- woven filter fabric. GZA can assist Parsons to size the underdrains if needed. Please call us with any questions. Very truly yours, GZA GEOENVIRONMENTAL, INC. Terese M. Kwiatkowski, P.E. Tracy L. Tarr, CWS, CESSWI Senior Principal Consultant/Reviewer TMK/TLT p:\01jobs\01.0171439.10 northampton bioretention ponds\test pit report\draft northampton test pit and soil infiltration report 022720 tmk1_ (002).docx Attachments: Figures Table Appendix A – Geotechnical Limitations Appendix B – Soil Test Pit logs Appendix C – Soil Test Pit Photo Log Figures SITE Copyright:© 2013 National Geographic Society, i-cubed © 2020 - GZA GeoEnvironmental, Inc. P:\01Jobs\01.0171439.10 Northampton Bioretention Ponds\Figures\Site Locus.mxd, 2/25/2020, 8:53:07 AM, lindsey.white1FIGURE 01.0171439.10FEBRUARY 2020 TLTERS LEW TMK LEW 1 in = 2,000 ft I-91 SB and NB Over Route 5 and B&M RRI-91 SB and NB Over Hockanum RoadNorthampton, Massachusetts LOCUS 4 PREPARED FOR: PARSONS100 HIGH STREETBOSTON, MASSACHUSETTS UNLESS SPECIFICALLY STATED BY WRITTEN AGREEMENT, THIS DRAWING IS THE SOLE PROPERTY OF GZAGEOENVIRONMENTAL, INC. (GZA). THE INFORMATION SHOWN ON THE DRAWING IS SOLELY FOR THE USE BY GZA'S CLIENTOR THE CLIENT'S DESIGNATED REPRESENTATIVE FOR THE SPECIFIC PROJECT AND LOCATION IDENTIFIED ON THEDRAWING. THE DRAWING SHALL NOT BE TRANSFERRED, REUSED, COPIED, OR ALTERED IN ANY MANNER FOR USE AT ANYOTHER LOCATION OR FOR ANY OTHER PURPOSE WITHOUT THE PRIOR WRITTEN CONSENT OF GZA, ANY TRANSFER,REUSE, OR MODIFICATION TO THE DRAWING BY THE CLIENT OR OTHERS, WITHOUT THE PRIOR WRITTEN EXPRESSCONSENT OF GZA, WILL BE AT THE USER'S SOLE RISK AND WITHOUT ANY RISK OR LIABILITY TO GZA. DATE: DESIGNED BY: PROJ MGR: PROJECT NO. DRAWN BY: REVIEWED BY: REVISION NO. SCALE: CHECKED BY: PREPARED BY: GZA GeoEnvironmental, Inc.Engineers and Scientistswww.gza.com DATEISSUE / DESCRIPTIONNO.BY Legend Test Pit Location Notes 1) Locations of test pits were made by tape measurements from nearby site features. Test pit locations should be considered accurate to the degree implied by the method used. 2)Test pits were observed and logged by GZA Test pits were performed by New England Boring Contractors of Brockton, Massachusetts on February 18, 2020. 3) Figure 2 - Test Pit Exploration Location Plan Figure 2A - Test Pit Exploration Location Plan Table TEST PIT HYDROLOGIC SOILS GROUP AND INFILTRATION RATES I-91 SB and NB Over Route 5 and B&M RR I-91 SB and NB Over Hockanum Road Northampton, Massachusetts BMP Area: I-91 Bioretention Pond Test Pit # Exploration Coordinates Existing Ground Surface Elevation (feet) Depth of Exploration (feet) Bottom of Exploration Elevation (feet) USDA Soil Textural Class NRCS Hydrologic Soil Group Rawls Rate Infiltration Rate (in/hour) Recommended Infiltration Rate (in/hour) (Rawl’s and NRCS) Depth to Estimated Seasonal High Water Table (feet) Elevation of Estimated Seasonal High Water Table During Exploration (feet) Depth to Bedrock (feet) Latitude Longitude 5 42°18'20.31"N 72°37'28.22"W 114.9 7 107.9 Silt loam/silt clay D/C 0.04-0.27 0.04 0.67 114.2 >7 6 42°18'21.69"N 72°37'27.44"W 114.8 7.2 107.6 Silt clay D 0.04 0.83 114 >7.2 7 42°18'22.77"N 72°37'26.38"W 114 7 107 Silt loam/fine sand C/A 0.27-2.41 0.83 113 >7 8 42°18'23.41"N 72°37'25.84"W 113.7 7 106.7 Silt clay/silt loam D/C 0.04-0.27 0.83 112.9 >7 9 42°18'23.19"N 72°37'25.30"W 112 6 106 Sand layer on top/silt loam at 18” C/A 0.27-2.41 1.5 110.5 >6 1 Exploration Coordinates were approximated using field sketches and Google Earth Pro, and do not represent surveyed GPS point coordinates. 2 Existing ground surface elevation was approximated using the plans entitled “Bridge Replacements N-19-059 and N-19-060, I-91 Over US Route 5 and B&M RR, I-91 Over Hockanum Road in Northampton, Hampshire County, MA: Bioretention Sheet 1 of 2 and Sheet 2 of 2,” dated October 16, 2019, provided by Parsons. 3 The NRCS Hydrologic Soil Group classifications were determined based on the USDA Soil Textural Class presented in Table 2.3.3 of the MassDEP Stormwater Management Regulations dated February 2008. It should be noted that hydrologic soil group classifications based on Table 2.3.3 are generic and do not take into consideration specific site conditions. If the basins are constructed as proposed, the bottom of each basin would not meet the minimum two foot vertical clearance to the top of the seasonal high water table per MassDEP Stormwater Management Regulations Volume 2, Chapter 2 and all test pits would be classified as Hydrologic Soil Group D. However, the observed seasonal high water tables are due to a perched water table conditions due to clay and silt soils, and is not a result of groundwater influence. 4 Rawls Rate infiltration rates are determined based on the USDA Soil Textural Class presented in Table 2.3.3 of the MassDEP Stormwater Management Regulations dated February 2008. 5 The Depth to Estimated Seasonal High Water is determined to be the depth below the ground surface where redoximorphic features are first observed in the soil profile. This is an estimated depth based on field conditions at the time of explorations and can fluctuate due to variations in season, rainfall, and other factors other than those existing at the time of explorations. It should also be noted that perched water table conditions were observed as a result of clay soils in the profile. 6 The Elevation of the Estimated Seasonal High Water Table is the ground surface elevation where observable redoximorphic features in the soil profile begin. This is an estimate based on field conditions at the time of explorations and can fluctuate as mentioned in note 5 above. File No: 01.0171439.10 Date: 2/18/2020 BMP Area: Route 5 Bioretention Pond GZA Personnel: James Long, NHCSS Lindsey White Test Pit # Exploration Coordinates 1 Existing Ground Surface Elevation (feet)2 Depth of Exploration (feet) Bottom of Exploration Elevation (feet) USDA Soil Textural Class NRCS Hydrologic Soil Group 3 Rawls Rate Infiltration Rate (in/hour)4 Recommended Infiltration Rate (in/hour) (Rawl’s and NRCS) Depth to Estimated Seasonal High Water Table (feet)5 Elevation of Estimated Seasonal High Water Table During Exploration (feet)6 Depth to Bedrock (feet) Latitude Longitude 1 42°18'23.41"N 72°37'23.28"W 114 7 107 Silt loam C 0.27 0.6 3.83 110.2 >7 2 42°18'23.24"N 72°37'23.27"W 114.5 7 107.5 Silt loam C 0.27 3.83 110.7 >7 3 42°18'23.01"N 72°37'23.12"W 113.7 8 105.7 Very fine sand A 2.41 3.67 110 >8 4 42°18'22.80"N 72°37'23.04"W 114 9 105 Very find sand A 2.41 3 111 >9 Appendix A – Geotechnical Limitations GEOTECHNICAL LIMITATIONS 01.0171439.10 Page | 1 February 2020 Proactive by Design USE OF REPORT 1. GZA GeoEnvironmental, Inc. (GZA) prepared this letter 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 Letter Report. Use of this letter 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 Letter 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 letter 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 letter 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 Letter Report. SUBSURFACE CONDITIONS 5. The generalized soil profile(s) provided in our Letter 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 letter report. 6. In preparing this letter report, GZA relied on certain information provided by the Client, state and local officials, and other parties referenced therein which were made available to GZA at 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 Letter Report) and monitoring wells at the specified times and under the stated conditions. These data have been reviewed and interpretations have been made in this Letter 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 Letter Report. GEOTECHNICAL LIMITATIONS 01.0171439.10 Page | 2 February 2020 Proactive by Design 8. GZA’s services did not include an assessment of the presence of oil or hazardous materials at the property. Consequently, we did not consider the potential impacts (if any) that contaminants in soil or groundwater may have on construction activities, or the use of structures on the property. 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. ADDITIONAL SERVICES 10. 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. Appendix B – Soil Test Pit Logs File No. 01.0171439.10 Evaluated by: GZA GeoEnvironmental, Inc. James Long, NHCSS Excavation Equipment Used: Kubota mini excavator Date: 2/18/2020 TP Subcontractor: New England Boring Contractors Weather: Low 30’s, overcast, intermittent snow and rain TEST PIT EVALUATION REPORT I-91 SB and NB Over Route 5 and B&M RR I-91 SB and NB Over Hockanum Road Northampton, Massachusetts Test Pit No. 1 NOTES: Route 5 Bioretention Pond Depth (inches) Description (NRCS) ^10-22 10YR3/2 Very dark grayish brown, gravelly loamy sand, granular, friable (fill) 22-30 10YR3/2 Very dark grayish brown, silt loam, massive, friable 30-46 2.5Y5/4 Light olive brown, silt loam, massive, friable 46-68 2.5Y4/3 Olive brown, silt loam, massive, friable 2.5Y6/2 Light brownish gray redoximorphic features 68-84 2.5Y4/2 Dark grayish brown, silt loam, angular, firm 2.5Y6/2 Light brownish gray redoximorphic features Estimated Seasonal High Water Table @ 46 inches Observed Water Table @ none inches Restrictive @ 68 inches Roots @ 50 inches Refusal @ none inches Test Pit No. 2 NOTES: Route 5 Bioretention Pond Depth (inches) Description (NRCS) ^0-16 10YR3/2 Very dark grayish brown, gravelly loamy sand, granular, friable (fill) 16-30 10YR3/2 Very dark grayish brown, silt loam, massive, friable 30-46 2.5Y4/4 Olive brown, silt loam, massive, friable 46-84 2.5Y4/3 Olive brown, silt loam, massive, friable 2.5Y6/2 Light brownish gray redoximorphic features Estimated Seasonal High Water Table @ 46 inches Observed Water Table @ none inches Restrictive @ none inches Roots @ 36 inches Refusal @ none inches 1 A layer of fill material is indicated by a “^” symbol. File No. 01.0171439.10 Evaluated by: GZA GeoEnvironmental, Inc. James Long, NHCSS Excavation Equipment Used: Kubota mini excavator Date: 2/18/2020 TP Subcontractor: New England Boring Contractors Weather: Low 30’s, overcast, intermittent snow and rain TEST PIT EVALUATION REPORT I-91 SB and NB Over Route 5 and B&M RR I-91 SB and NB Over Hockanum Road Northampton, Massachusetts Test Pit No. 3 NOTES: Route 5 Bioretention Pond Depth (inches) Description (NRCS) ^0-26 10YR3/2 Dark brown, gravelly loamy sand, granular, friable (fill) 26-44 2.5Y4/4 Dark brown, very fine sand, granular, friable 44-60 2.5Y4/3 Yellowish brown, very fine sand, granular, friable 2.5Y6/2 Light brownish gray with 7.5YR4/6 Strong brown redoximorphic features 60-96 2.5Y4/2 Light olive brown, very fine sand, granular, friable 2.5Y6/2 Light brownish gray with 7.5YR4/6 Strong brown redoximorphic features Estimated Seasonal High Water Table @ 44 inches Observed Water Table @ none inches Restrictive @ none inches Roots @ 30 inches Refusal @ none inches Test Pit No. 4 NOTES: Route 5 Bioretention Pond Depth (inches) Description (NRCS) ^0-16 2.5Y3/2 Very dark grayish brown, gravelly loamy sand, granular, friable (fill) 16-36 5YR4/3 Reddish brown, sand, single grain, loose 36-108 2.5Y4/3 Olive brown, very fine sand, granular, friable 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features Estimated Seasonal High Water Table @ 36 inches Observed Water Table @ none inches Restrictive @ none inches Roots @ 40 inches Refusal @ none inches File No. 01.0171439.10 Evaluated by: GZA GeoEnvironmental, Inc. James Long, NHCSS Excavation Equipment Used: Kubota mini excavator Date: 2/18/2020 TP Subcontractor: New England Boring Contractors Weather: Low 30’s, overcast, intermittent snow and rain TEST PIT EVALUATION REPORT I-91 SB and NB Over Route 5 and B&M RR I-91 SB and NB Over Hockanum Road Northampton, Massachusetts Test Pit No. 5 NOTES: I-91 Bioretention Pond Depth (inches) Description (NRCS) 0-8 2.5Y3/2 Very dark grayish brown, silt loam, granular, friable 8-32 5Y4/2 Olive gray, silty clay, angular blocky, firm 5Y6/1 Gray and 7.5YR4/6 Strong brown redoximorphic features 32-40 2.5Y4/3 Olive brown, sand, single grain, loose 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features 40-84 5Y4/1 Dark gray, silt loam, angular blocky, firm 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features Estimated Seasonal High Water Table @ 8 inches Observed Water Table @ none inches Restrictive @ 8 inches Roots @ 16 inches Refusal @ none inches Test Pit No. 6 NOTES: I-91 Bioretention Pond Depth (inches) Description (NRCS) 0-10 2.5Y3/2 Very dark grayish brown, silty clay loam, granular, friable 10-42 5Y4/2 Olive gray, silty clay, angular blocky, firm 2.5Y6/2 Light brownish gray redoximorphic features 42-70 2.5Y4/3 Olive brown, silt loam, angular blocky, firm 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features 70-86 5Y4/1 Dark gray, silty clay, angular blocky, firm 5Y6/2 Light olive gray and 7.5YR4/6 Strong brown redoximorphic features Estimated Seasonal High Water Table @ 10 inches Observed Water Table @ none inches Restrictive @ 10 inches Roots @ 26 inches Refusal @ none inches File No. 01.0171439.10 Evaluated by: GZA GeoEnvironmental, Inc. James Long, NHCSS Excavation Equipment Used: Kubota mini excavator Date: 2/18/2020 TP Subcontractor: New England Boring Contractors Weather: Low 30’s, overcast, intermittent snow and rain TEST PIT EVALUATION REPORT I-91 SB and NB Over Route 5 and B&M RR I-91 SB and NB Over Hockanum Road Northampton, Massachusetts Test Pit No. 7 NOTES: I-91 Bioretention Pond Depth (inches) Description (NRCS) 0-10 2.5Y3/2 Very dark grayish brown, silt loam, granular, friable 10-26 2.5Y4/2 Dark grayish brown, silt loam, angular blocky, firm 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features 26-48 5Y4/2 Olive gray, silt loam, angular blocky, firm 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features 48-84 2.5Y4/3 Olive brown, very fine sandy loam, granular, friable 2.5Y6/2 Light brownish gray redoximorphic features Estimated Seasonal High Water Table @ 10 inches Observed Water Table @ none inches Restrictive @ 10 inches Roots @ 26 inches Refusal @ none inches Test Pit No. 8 NOTES: I-91 Bioretention Pond Depth (inches) Description (NRCS) 0-4 10YR3/3 Dark brown, loamy very fine sand, granular, friable 4-10 2.5Y4/4 Olive brown, loamy sand, granular, friable 10-20 2.5Y4/3 Olive brown, loamy sand, granular, friable 2.5Y6/2 Light brownish gray and 7.5YR4/6 Strong brown redoximorphic features 20-64 Gley 1 4/10Y Dark greenish gray, silty clay, angular blocky, firm 64-84 5Y4/2 Olive gray, silt loam, angular blocky, firm 5Y6/2 Light olive gray redoximorphic features Estimated Seasonal High Water Table @ 10 inches Observed Water Table @ none inches Restrictive @ 20 inches Roots @ 22 inches Refusal @ none Inches File No. 01.0171439.10 Evaluated by: GZA GeoEnvironmental, Inc. James Long, NHCSS Excavation Equipment Used: Kubota mini excavator Date: 2/18/2020 TP Subcontractor: New England Boring Contractors Weather: Low 30’s, overcast, intermittent snow and rain TEST PIT EVALUATION REPORT I-91 SB and NB Over Route 5 and B&M RR I-91 SB and NB Over Hockanum Road Northampton, Massachusetts Test Pit No. 9 NOTES: I-91 Bioretention Pond Depth (inches) Description (NRCS) 0-6 2.5Y3/3 Dark olive brown, very fine sandy loam, granular, friable 6-18 5Y4/3 Olive, sand, single grain, loose 18-60 2.5Y4/3 Olive brown, silt loam, angular, firm 2.5Y6/2 Light brownish gray redoximorphic features 60-72 2.5Y4/3 Olive brown, very fine sand , granular, friable 2.5Y6/2 Light brownish gray redoximorphic features Estimated Seasonal High Water Table @ 18 inches Observed Water Table @ none inches Restrictive @ 18 inches Roots @ 20 inches Refusal @ none inches Appendix C – Soil Test Pit Photo Log APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 1: Rt 5 Bioretention Pond: View of Test Pit 1. Photograph No. 2: Rt 5 Bioretention Pond: View of soils excavated from Test Pit 2. APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 3: Rt 5 Bioretention Pond: View of soils excavated from Test Pit 3. Photograph No. 4: Rt 5 Bioretention Pond: View of Test Pit 4. APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 5: I-91 Bioretention Pond: View of Test Pit 5. Photograph No. 6: I-91 Bioretention Pond: View of soils excavated from Test Pit 5. APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 7: I-91 Bioretention Pond: View of Test Pit 5. Photograph No. 8: I-91 Bioretention Pond: View of Test Pit 6. APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 9: I-91Bioretention Pond: View of Test Pit 7. Photograph No. 10: I-91 Bioretention Pond: View of soils excavated from Test Pit 7. APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 11: I-91 Bioretention Pond: View of Test Pit 8. Photograph No. 12: I-91 Bioretention Pond: View of soils excavated from Test Pit 8. APPENDIX C – TEST PIT PHOTO LOG Route 5 and I-91 Bridge Replacement Infiltration Basin Test Pits Northampton, Massachusetts Photos Taken: February 18, 2020 01.0171439.10 GZA GeoEnvironmental, Inc. Photograph No. 13: I-91 Bioretention Pond: View of Test Pit 9. Photograph No. 14: I-91 Bioretention Pond: View of soils excavated from Test Pit 9.