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OTO_360 Riverside Drive 3rd Party Evaluation July 2022.pdf P0285-40-01 August 1, 2022 City of Northampton 210 Main Street, Room 11 Northampton, Massachusetts 01060 Attention: Sarah LaValley, Conservation, Preservation & Land Use Planner Re: Third-Party Review - Notice of Intent 360 Riverside Drive Northampton, Massachusetts Dear Ms. LaValley: As requested, O'Reilly, Talbot & Okun Associates, Inc. (OTO) has performed a review of the Notice of Intent (NOI) that was filed with the Northampton Conservation Commission by Epsilon Associates, Inc. (Epsilon) on behalf of Cutlery Building Associates (CBA) (updated April 19, 2022) for work proposed at the above-referenced property (the Site), which is located along the Mill River. OTO has performed this third-party review at the request of the City of Northampton. BASIS FOR THE THIRD-PARTY REVIEW A third-party review of the NOI was requested by the City of Northampton to determine if the alternative provided by the applicant and selected for the project is the alternative that will cause the least impact the wetland habitat and river resource areas. The purpose of the review is to provide professional support to the City of Northampton Conservation Commission in understanding if the proposed alternative should be permitted as a limited project based upon the provisions of the Massachusetts Department of Environmental Protection (MassDEP) Wetlands Protection Regulations, specifically 310 CMR 10.53(3)(q). The purpose of the review is not to redesign the alternative that has been presented or provide additional alternatives to the one that was presented in the NOI, but to evaluate whether the selected alternative and plan to implement it is the least impactful to the riverine environment. LIMITED PROJECT PERFORMANCE STANDARDS Multiple alternatives to reach a level of No Significant Risk (NSR) were considered since 2011 in the Temporary Solution Report, and again reconsidered in the 2011 and 2016 Periodic Reviews of the Temporary Solution for Area of Concern (AOC)-2 and AOC-3. Since 2011, there have been no feasible alternatives to reach NSR for the Temporary Solution portions of the Site. Since then, funds from the pending sale of a portion of the property made the engineered barrier alternative the best pathway to achieving NSR and a Permanent Solution at the Site. Throughout this process, although these alternatives were focused on the achieving NSR for the release condition, the alternatives presented in the 2022 Phase IV RIP meet the standard of the Wetland regulations pursuant to 310 CMR 10.53(3)(q)1. Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 2 The 2021 LSP inspection of the Site identified several areas of bank stabilization efforts that were less impactful to the resource area as ineffective in preventing erosion of contaminated soils. Since 2005, those less impactful alternatives were performed and although they stabilized the banks for approximately 3 years, they were not effective in long term stabilization that could result in No Significant Risk and a Permanent Solution for the Disposal Site. IDENTIFICATION OF PROPOSED ALTERNATIVES AND CONSIDERATION OF IMPACTS Epsilon provided a single multi-step remedial alternative in the NOI. The Wetlands Protection regulations 310 CMR 10.53 (3)(q) indicates that a Comprehensive Remedial Alternative that is selected in accordance with provisions of the MCP (310 CMR 40.0851 through 40.0869) shall be deemed to meet 310 CMR 10.53(3)(q)(1) of the Wetlands regulations. This section of the Wetlands regulations further states that the “…projects shall be designed, constructed, implemented, operated, and maintained to avoid, or where avoidance is not practicable, to minimize impacts to the resource areas…” We developed considerations and questions in our review for each step and various aspects of the selected remedial alternative. OTO recommends that these questions or concerns be presented to the applicant for response and clarification. Repoint Vertical Mortared Wall It is unclear in the NOI if there is land to stand on at the base of the wall during the repointing activities or if the wall is partially submerged. The application doesn’t indicate if dewatering is required to repoint the bottom of this wall. The NOI and plan C4.4 indicate the wall will be accessed by timber mats and the mats are located at an elevation between the mean low water line and ordinary/mean highwater line. Our comments on timber matting are in a separate section below. Remove Trees & Lower the Slope of the Bank The Mill River is identified as a cold-water fishery. Loss of tree cover and shading could potentially influence temperature of the water altering habitat as it flows past the cleared area. The applicant has not explained how the loss of canopy will impact the fishery and how potential impacts will be monitored. There is special concern regarding removal of the larger diameter at breast height (DBH) trees, as these higher canopy trees provide the most shade. This is a short-term and long-term concern since the applicant does not indicate in the NOI that any tree canopy restoration is planned. OTO questions if a shade study been completed to evaluate the concern of how reduced shading could impact the cold-water fishery. Generally, the presence of plant roots increases bank stabilization. By cutting 96 trees and removing their root balls, the bank may lose stabilization until matting is placed. Although detailed excavation, fill, erosion control, mat barrier placement procedures are Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 3 provided on Plans C8.1 and C8.2, OTO has the following questions regarding this step of implementation of the remedial alternative:  What is the timeline for each phase of work? This information would be helpful to understand the duration of time the bank would be cleared from trees and vegetation and exposed before stabilization activities (e.g., reinforcement with matting);  During this period of time, how would the exposed bank be protected from erosion from stormwater?  Are there any areas of trees, specifically larger trees, that could be retained? We understand the concern of trees falling and destabilizing the bank. Instead of removing the trees while they are viable, could a tree monitoring program be implemented that would assess the viability and stability of the trees on a regular basis, and include planned felling of trees that appear to be in poor condition or in danger of destabilizing the bank?  Could the clearing work be performed in a step-wise, section-by-section process that would reduce the area of soil that is disturbed and exposed at the same time?  Much of the described work will include operation of heavy equipment in or in close proximity to multiple resource areas. Specifically, what measures will be taken to prevent spills (which includes a sheen on surface water) to the environment? Will there be an oil-only sorbent boom placed inside the turbidity curtain?  Is the planting of shrubs, starter plants, or saplings planned in the restoration plans or will the area only be replanted using wetland seed mixes? Variation in canopy height is important to restoring the habitat and providing shade to the cold-water fishery. There are additional concerns regarding the loss in shading in uplands habitat and potential temperature changes due to loss in canopy cover and the impact on the habitat of the endangered species (Ocellated Darner) identified in this area. Re-build Collapsed Dry-laid Stone Wall OTO has the following questions regarding the re-building of the dry-laid stone wall to support the levee:  Is the re-build only adding to the height of the wall?  Where are portions of collapsed dry-laid stone wall?  What is the length collapsed portions of wall to be rebuilt?  Was there consideration to rebuild this area as a gabion wall if there are intact areas of the base of the wall?  Will there be any replication for the loss of wetland area for the installation of the dry-laid bolder retaining wall located to the west of the isolated wetland?  Long term, this wall may improve the wetland holding capacity. Would a replication area improve the applicant’s ability to meet the general performance standard? Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 4 Gabion Wall OTO has the following question regarding the installation of the gabion wall:  Where are the sections of the collapsed wall located? We were unable to identify specific portions of the wall that are compromised on the plans provided by the applicant.  What is the length of the collapsed wall to be replaced with gabion wall? Extend Retaining Wall OTO has the following questions regarding the extension of the retaining wall:  During construction, how will intermittent increased stream flow and stage changes in the Mill River due to unexpected storms be managed?  In areas where a turbidity curtain is used around the timber matting, is the curtain where it is attached to the bank placed at a high enough elevation to withstand the fluctuation in river water?  The implementation plan indicated that a silt fence will be placed along the shoreline even where there is a turbidity curtain. The plans be adjusted to depict this. OTO suggests that the stones used to extend the walls should not be collected from the riverbed but should be brought in from an outside source if they are not from a previously collapse portion of the wall. As noted on Page 12 of the NOI, habitat for the endangered Ocellated Darner includes shaded, clear, cold, rocky streams and rivers and associated shaded uplands. OTO has concerns that removing native rocks from the streambed may further degrade the habitat of the dragonfly, which is already being altered by the removal of shading trees and other plantings. Stone Rip-Rap OTO notes that rip-rap rock is actually good for the identified endangered species habitat as long as there is enough shading. This could be considered an improvement for the habitat especially because the habitat some has already been lost due to the last expansion of the stockpile. OTO has the following question regarding the rip-rap placement above the retaining wall:  Is this area part of the engineered barrier? Will the fabric, gravel, and rip-rap need to be surveyed in between each stage for the AUL? Geocell Turf Reinforcement Mat Treatment OTO has the following questions regarding the geocell turf reinforcement mat that is planned along the reworked slope above the rip-rap.  Is this area considered part of the engineered barrier? Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 5  If it is not within the engineered barrier, can any saplings be planted along this slope? Saplings and their root structures could be beneficial as they act as natural anchors for the matting in addition to providing shade and variable heights of canopy. Soil Stabilization OTO has the following questions regarding the application of metals stabilization materials to soils along the levee and the levee bank to the top of the stone retaining wall:  Will soils that are assumed to be contaminated located at the base of the excavated grade be treated with Blastox before the filter fabric in rip-rap area or geocell mat is placed?  The application of the Blastox metals stabilization materials will occur in situ and require soil mixing. What measures will be taken to prevent accidental releases of the Blastox to the waterway? How will materials be stored on Site?  Will application timing be limited to dry conditions to eliminate Blastox material from running off into a resource area creating unintended treatment of river sediment, potentially impacting the uptake of natural minerals within that resource area. A response to these questions could be provided in a spill prevention plan.  If the Blastox application will result in stabilization of the metals-contaminated soil such that the metals are no longer leachable, what is the reasoning for stockpiling the soil? If the metals are no longer leachable, the materials could theoretically be eligible for transportation as non-hazardous remediation waste and would eliminate the need for expansion of the stockpile.  Was excavation of the soil, stockpiling, and treatment in an area away from the riverbank followed by disposal after treatment considered? Stockpile Excavated Soil The original plans submitted in the NOI discussed work within the southern end of the Isolated Wetland. Revisions submitted by the applicant indicate that loss of the southern end of the Isolated Wetland is no longer a concern. OTO has the following questions regarding the stockpile:  Based on the revisions, an area that has a UCL exceedance will not be capped by the engineered barrier. Will a Permanent Solution with Conditions still be achievable if this area is not capped?  Is the stockpile engineered barrier permeable? Is an impermeable membrane not required because the soil is being treated with Blastox?  Instead of the stockpile being stabilized with grass, would the applicant consider a pollinator mix and a wetland mix on the northern end of the stockpile? Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 6  Has additional stormwater runoff from the stockpile to the parking lot to the south been considered? From our limited site visit (from the street), we have concerns about the holding capacity and competency of the existing stormwater outfall if an impermeable membrane is used on the stockpile. Additionally, OTO questioned whether a stormwater management will be in place during implementation activities? OTO recommends the limits of the final stockpile not to exceed existing dimensions. If soil quantities to be excavated and moved to the stockpile exceed the pre-approved stockpile limits, shipment off Site for disposal should be considered. Removal of Organic Matter OTO has the following questions regarding the removal of organic matter along the riverbank:  What is the nature of the timber matting that will be used for the log-mat road and the road parallel with the levee? Our concern is that the wood for the matting could contain creosote or arsenic soaked wood if they are constructed from former utility poles or railroad ties. Do these types of timber mats have treatments that could impact resource areas? Note: A sheen observed on a surface water is a reportable release condition.  How does the lower area access road connect to the construction entrance? Where is the access road? Is the planned access road permanent or temporary?  Can the work be performed on the access road without the width of the access road being 36’ wide? Additional questions regarding the access roads are provided in the following section.  Can the crane stabilization areas be defined and kept outside of the Isolated Wetland (IW)? The Erosion controls plan depicts silt fence around IW and Site preparation plan (C4.3) depicts timber map placement across more than ½ of the IW. OTHER PROJECT SPECIFICS OTO has the following general questions regarding implementation of the remedial alternative and its potential for temporary or permanent impacts to the wetland: Access Road  We would like additional details regarding the constructed 12’ wide access road. Is this a permanent or temporary disturbance? Will compacted sublayers be removed? Will there be other plantings or just seeding? Will this be installed with the intension of using it to access the area by foot or by vehicle in the future? If Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 7 vehicular traffic is not planned once the excavation and stabilization work is completed, can native shrubs or trees be planted along or within this access road?  Once the remedial alternative has been implemented, will the planned construction entrance be restored? Post-Excavation Sampling  There are 20 proposed post-excavation samples planned for a 35’ x 650’ area. Is this sampling frequency adequate to demonstrate effectiveness of the Blastox application? OTO would recommend that TCLP testing also be performed to confirm that the application has effectively stabilized the metals. Engineered Barriers  What are the planned limits of the engineered barrier(s)? There are several types of engineered barriers planned. Since leachability of metals is being stabilized through the application of Blastox, it appears each of these barriers is permeable. If it is permeable, is it possible to replant saplings anywhere there is not an engineered barrier required for the AUL?  Will the fabric under the rip-rack rock be considered an engineered barrier? Fencing  As part of the requirements of the AUL (specifically related to arsenic), will the chain link fence need to be restored? Post Completion Monitoring  The current post-completion monitoring plan sets a goal of 75% cover after two years. Past erosion control measures implemented at the Site have lasted approximately 2-3 years before erosion began. OTO would recommend monitoring for five years to ensure the erosion controls are effective for at least as long as the temporary controls that have previously been implemented. Specifically, higher frequency monitoring should occur in initial months following completion of the alternative, followed by a reduction in frequency over the next few years. The monitoring program should require inspections following spring highwater and after large storm events.  The plan did not specify the post-implementation duration, or frequency of temperature monitoring of the Mill River to evaluate the long-term impacts of the removal of shade plantings. OTO also had questions regarding the monitoring of water quality changes in the river and whether the post-completion monitoring program accounted for large storm events and changes in the river level.  As noted above, OTO would recommend the planting of starter plants, wetland shrubs, or saplings in addition to the wetlands mix to increase the height variability Third-Party Evaluation of NOI 360 Riverside Drive Northampton, Massachusetts August 1, 2022 8 and coverage of the canopy in areas where practicable and where the plantings do not interfere with engineered barriers. Restoration or Replication  As noted above, OTO believes that alternative restoration and/or replication of wetland habitats may be possible that would reduce the overall long-term impact of the project on these wetlands. Additional Mitigation Measures  If large areas of the project area are to be unvegetated for a substantial period of time during the implementation of the remedial alternative, OTO would recommend the placement of dust monitors upwind, downwind, and at the southern end (closest to the nearest inhalation receptor). OTO would recommend logging intervals of 30 minutes. OTO also recommends that dust suppression should be supplied by a contractor-provided water source (tank trailer). The plan should stipulate that the source of dust suppression water will not be the Mill River. OTO personnel are available to attend a Site visit and/or attend conservation commission meeting(s) with the Site owners, the LSP-of-record, and city officials, if requested. These services can be provided on a Time and Materials basis in addition to the proposal we have fulfilled by completing this review. We thank you for the opportunity to provide our services to the City of Northampton. Sincerely yours, O'Reilly, Talbot & Okun Associates, Inc. Sabrina A. Moreau Lori McCarthy, LSP Project Manager Senior Project Manager