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Home My WebLink AboutStormwater Report - 315 TURNPIKE STREET 1/10/2012 Egg8estq,��r'i Environmental September 28, 2011 North Andover Planning Board l6OU Osgood Street North Andover, M/\ 0l845 z11 u: Jndy1,ymnu, Iop/o Planner North Andover Conservation Counmiaoioo IdOO Osgood Street North Andover, MA 0 184 Attn: Jennifer Hughes, Conservation Coordinator IlB: Stnnmvvetcr Management Review Merrimack College, Volpe Center Expansion Dear Ms. 7vonooand Ms. Hughes: Per your request, Ibavn conducted an initial technical review of the submissions filed in support of Merrimack College's Application for Site Plan Approval and Notice of Intent (NOI) for the proposed Volpe Center Expansion with respect to stormwater managernent. Included in the 000tsdala I received and reviewed were the lbUovviog: � � * /\ogoot 5, 2011 Cover Letter and Site Plan/\oorovu\Application, including Fiscal and Community Impact Statements � * Notice of bdeut' Volpe Athletic Center Expansion, prepared for Mer/bnuob � College hy\/anaaaeIIooAnoBruudio^ Inc. /\/HB\' dated August l2, 2011. Is Btorou9a1crIlepod, Athletic Center Expansion, prepared for Merrimack College hyYanaoamIlungou8ruadiu, Inc. /l/8U0\, dated August, 20l|. M Site Plans Issued for I.00n| Perm htiog,\/n|no Athletic Center Bxynumioo` 325 Turnpike St, Sbcc10 C-1 —C-6, I.'l, and S\/-1, prepared by \/ouamoo l{ungon 8runtlin, Inc, (\/IIB), dated August 5, 20lI, revised through August l2, 2U|I. � I also conducted o brief site visit to the property to observe existing conditions and � drainage patterns. Most recently, l received and reviewed a September 2l, 2011 letter to the Conservation Commission bonn Jeff I)uggat of Merrimack College, outlining several conceptual design alternatives for the project. 9Wv primary focus in this initial review is no the overall o(orm*'oter cuauugoruout approach and design 0000ey1m used in the project, as well as its oonzpUaooc with the Town of North Andover's xnubug rcguire0000io for Site Plan Review, the K8unonobuan1im Wetlands Protection /\d (VVPA), the North Andover Wetlands Bylaw, and the Massachusetts Department of Environmental Protection (DBP) StounvvckocM4nuogouzeo1 Standards and Regulations. My comments are aimed at assisting both the Planning Board and the Conservation Cncoonisnlon in their respective coviovvo of the project. 32 Old FramiDgha0Rd Unit 39 5UdburyNA 01776 teL5OB.Z59.1137 fax 866.820.7840 Volpe Athletic Center,Technical Review 2 September 28, 2011 The project site is the Volpe Athletic Complex, which occupies an approximately 10.7 acre area of the Merrimack College Campus located between Cullan Avenue and Salem Turnpike. The site includes the existing 79,000 sf building, a paved parking area to the west of the building, two asphalt tennis courts to the east of the building, and associated landscaping. Immediately to the north of the site are two vegetated wetland systems. Surface drainage on the property is generally in a southerly direction, to the existing closed drainage system in Cullan Ave. and through that system to a discharge location within the Town of Andover. However, some portion of the existing building roof is discharged through two outfalls to the wetland to the northeast of the building. The two tennis courts and the area to the east of the building also drain overland to the same wetland. The proposed project calls for an approximately 76,000 sf expansion and modification of the existing Volpe Center building, in conjunction with several infi•astructure improvements, including a new parking area in the area of the existing tennis courts, and reconfiguration of the existing parking lot to the west of the building. As proposed, runoff from the new parking area would be treated onsite and redirected to the closed drainage system on Cullan Avenue. My comments are outlined below: 1. The proposed project is considered a mix of new development and redevelopment under Standard 7 of the DEP Stormwater Management Standards, since the site is previously developed but a net increase in impervious area is proposed. All new impervious areas on the site are fully subject to the requirements of the ten state standards, and existing stormwater discharges on the site are subject to Standards 1, 7, 8, 9, and 10 fillly, and Standards 2 through 6 to the "maximum extent practicable", i.e. reasonable effort must be made to comply filly with these standards and the project should be implementing the highest practicable level of stormwater management. A redevelopment project must also improve existing conditions. While the proposed project is aimed at complying with the DEP standards for the expanded building and new parking area, nothing is currently being proposed to bring existing stormwater discharges into compliance or to improve existing conditions. 2. The Applicant makes the case that drainage fi-om the project site is covered under a Stormwater Master Plan, for which the Andover Conservation Commission issued an Order of Conditions in October, 2001, and that the detention basin(s) to which the project area drains have adequate capacity (flow "credit§") to attenuate the projected flow rates. The Plan and the approved Order of Conditions (OOC) fi-om the Andover Conservation Commission were included in the submittal but it is unclear whether the basins were ever constructed and, if so whether they were built in accordance with the approved design and maintained accordingly. In addition, it appears from this material that the "wetland/football field basin" is actually a berm designed to detain flow within the naturally occurring wetland Volpe Athletic Center;Technical Review 3 September 28, 2011 system to the south and west of the football field. The current DEP stormwater regulations prohibit the use of wetland resources for this purpose; all of the stormwater standards including peals rate attenuation need to be met prior to discharge to a wetland resource. 3. Subcatchment M-113-1 discharges to the wetland to the northeast of the building (Wetland 2) through what appears to be two roof drain outlets, as well as in the form of overland flow in area to the east of the building, including the tennis courts. In order to more accurately assess impacts on that wetland, these areas should be modeled individually and the wetland treated as a separate design point. 4. The building extension in the southeast corner of the existing building has roof drains along the eastern wall and looks like it should be included in the Existing Conditions Subarea M-1B-1, not in M-1B-3A which discharges to the south. 5. Additional information on the proposed modifications and additions to the building are needed in order for me to better understand the roof drainage areas modeled. The plans merely show the footprint of the building, but it appears that a number of existing roof drains are being redirected. 6. The hydrologic calculations should include the 1-year storm, in accordance with the North Andover Wetlands Bylaw. In addition, impacts to both the rate and the volume of discharge need to be quantified for each wetland resource, and flow paths and control points should be shown on the pre-development and post- development watershed maps. 7. The three pipes exiting the existing building at the concrete headwall on the south side of the building are unlabelled;what is the source of the discharge? 8. Appendix A contains rip rap sizing calculations for three outfalls; FES-1, FES- Roof-North and FES-Roof-South. However, only two outfalls are shown on the on the design plans and both are unlabeled and on the north side of the building. In addition, it is unclear what the basis for the discharge rates used in the calculations is;they do not correspond to the HydroCAD calculations. 9. The design plans call for replacing the existing drain line that extends south from DMH-2 in Cullan Ave. A significant portion of the flow fi•om the proposed project will be discharged to the 15-inch drain from CB-1 and not the drain from DMH-2; has it been determined that this drain has adequate capacity to accommodate the increased flow? 10: The proposed plan makes no effort to offset lost recharge on the site, on the basis that the soils are poor (HSG C and D) and the groundwater table is high, and that it is consistent with the Stormwater Master Plan Approval by the Andover Conservation Commission. The Andover OOC does not provide any such waiver of recharge requirements, except for projects entailing < 2,000 sf net impervious Volpe Athletic Center,Technical Review 4 September 28, 2011 area within the Town of Andover, and I do not believe it has any bearing on wetlands permitting by the Town of North Andover. Stormwater Management Standard 3 does require that sites comprised solely of C and D soils comply with the recharge requirement "to the maximum extent practicable", e.g. the applicant must make all reasonable efforts to meet the Standard, including evaluating alternatives that minimize impervious surfaces. The Geotechnical study conducted by McPhail Associates indicated that groundwater levels in the areas studied (to the south and west of the building) range from 2 to 4 ft below grade, suggesting that there should be some opportunity for infiltration on the site. Alternatively, I would suggest that the college might be able to provide compensatory recharge elsewhere on the campus. 11. 1 am aware that Merrimack College and VHB recently submitted two conceptual design alternatives outlined in a letter to the Conservation Commission dated September 21, 2011. The plans include several design modifications aimed at minimizing buffer zone incursion, shrinking and relocating the new parking lot and providing LID elements in the form of a rain garden. Based on the configuration and proposed grading it does not appear that any of the paved areas on the site would drain to the rain garden, therefore I presume that its purpose would be to capture and recharge roof runoff only. While this may address the requirement to provide groundwater recharge to the maximum extent practicable on the site, additional detail on the soils in that area and projected recharge volume would be needed. 12. The treatment train for the proposed new parking lot is comprised of deep sump catchbasins and an in-line Stormeeptor 450i treatment unit. The calculations use a 75% TSS removal credit for the Stormeeptor unit based on the NJCAT evaluations cited on the MASTEP website. The NJCAT evaluation did corroborate a 75% TSS removal rate for the unit in laboratory studies; however their approved TSS removal rate for field installations is 50%. This is the removal rate that should be used in the TSS removal calculations. 13. The existing catchbasins in Cullan Avenue are in-line and in series, one has a broken grate, and in all likelihood they do not have deep sumps or oil/debris hoods. Even if flow attenuation is provided further downstream in the system, the proposed increase in the flow rate discharged through these storm drains has the potential to mobilize sediments accumulated in the catchbasins. Consideration should be given to moving the catchbasins in Cullan Avenue (particularly CB-1 through which much of the proposed flow is discharged) offline and upgrading them with deep sumps and outlet hoods. 14. The proposed plan does not call_ for any drainage improvements for the existing parking area to the west of the building, even though the parking lot is being reconfigured. It is unclear what condition the existing catchbasins serving this lot are in and whether they provide any degree of water quality treatment. Volpe Athletic Center,Technical Review 5 September 28, 2011 15. The application does not address the fact that there is an approved Total Maximum Daily Load allocation (TMDL) for bacteria in the Shawsheen River basin, and that the Town is required through its Phase 2 NPDES Permit to reduce the discharge of these pollutants. To the maximum extent practicable, the project should employ stormwater BMPs that are effective at addressing these pollutants, e.g. through filtration or infiltration. 16.As is indicated in the Stormwater Management Report, the proposed project entails the disturbance of more than one acre and will therefore require a Construction Stormwater Pollution Prevention Plan(SWPPP) filed under the EPA General Permit. I recommend that the Construction S WPPP be prepared by or in conjunction with the contractor selected for project construction, and that the Conservation Commission and Planning Board have adequate time to provide input prior to the plan being filed. 17.Measures to prevent illicit discharges from the proposed project are addressed in the Long-Term Pollution Prevention Plan. They are, however, somewhat generic and not specific to the sports facility or the nature of the operations. More specific snow storage areas need to be designated, and the use of alternative deicers should be discussed, particularly in wetland buffer areas. An Illicit Discharge Statement is also required under Standard 10 and has not been submitted. Given that the existing building is being rehabbed rather than replaced, that some portion of the interior plumbing (roof drains) appear to discharge directly to the wetland, and that the Shawsheen River has an approved TMDL for elevated levels of bacteria largely attributed to illicit discharges, the existing building should be thoroughly dye-tested to confirm that there are no illicit connections to the storm drain system. I appreciate the opportunity to assist the North Andover Planning Board and Conservation Commission with the review of this project, and hope that this information is suitable for your needs. Please feel free to contact me if you or the applicants have any questions regarding the issues addressed herein. Sincerely, EGGLESTON ENVIRONMENTAL Lisa D. Eggleston, P.E. i Transportation Land Development Environmental ° S e r v i c e s I imagination mnovato ton I energy Creating results for our clients and benefits for our communities i October 18,2011 yanasse Haneen Brustlin, Inc Mr.John Simons,Chairman North Andover Planning Board 1600 Osgood St.-Bldg 20-Suite 2-36 North Andover,Ma 01845 North Andover,Massachusetts Mr.Louis Napoli,Chairman North Andover Conservation Commission 1600 Osgood Street,Suite 2-36 North Andover,MA 01845 Re: Response to Stormwater Peer Review Comments DEP File#:242-1531 Volpe Athletic Center Expansion—Merrimack College North Andover,Massachusetts Dear Chairmen Board members and Commissioners, r On behalf of Merrimack College,VHB provides the following information in response to the peer review comment letter prepared by Eggleston Environmental and dated September 28,2011. The responses also reflect input from a coordination meeting with Eggleston Environmental and the Town of North Andover on October 13,2011. The site plans have been revised to reflect these comments as well as the previously discussed concepts to pull the proposed building expansion out of the"50-foot"No-Build Zone". The Eggleston Environmental comments are listed below,followed by the response in italics. Comment: 1. The proposed project is considered a mix of new development and redevelopment under Standard 7 of the DEP Stormwater Management Standards,since the site is previously developed by a net increase in impervious area is proposed. All new impervious areas on the site are fully subject to the requirements of the ten state standards,and existing stormwater discharges on the site are subject to Standards 1,7,8,9,and 10 fully,and Standards 2 through 6 to the"maximum extent practicable",i.e.reasonable effort must be made to comply fully with these standards and the project should be implementing the highest practicable level of 101 Walnut Street Post Office Box 9151 Watertown,Massachusetts 02471-9151 L:V 617.924.1770 ■ FAX 617.924.2286 1625.00\does\letters\StonmvaterRTC.doc email:info @vhb.com www,vhb.com Stormwater Response to Comments Project No.: 11625.00 October 18,2011 Page 2 stormwater management. A redevelopment project must also improve existing conditions. While the proposed project is aimed at complying with the DEP standards for the expanded building and new parking area,nothing is currently being proposed to bring existing stormwater discharges into compliance or to improve existing conditions. i Response:The project design has been modified to include stormwater quality improvements along Cullen Avenue and portions of the lobby parking lot.This includes the addition of a water quality structure and new catchbasins with deep sumps and hoods. Additional outlet protection is also proposed at existing roof drain outlets adjacent to Wetland 2. j Comment: j 2. The Applicant makes the case that drainage from the project site is covered under a Stormwater Master Plan,for which the Andover Conservation Commission issued an Order of Conditions in October,2001,and that the detention basins were ever constructed and,if so whether they were built in accordance with the approved design and maintained accordingly. In addition,it appears from this material that the"wetland/football field basin" is actually a berm designated to detain flow within the naturally occurring wetland system to the south and west of the football field. The current DEP stormwater regulations prohibit the use of wetland resources for this purpose;all of the stormwater standards including peak rate attenuation need to be met prior to discharge to a wetland source. Response: The improvements detailed in the Stormwater Master Plan were constructed in 2001-2002 and modifications were made in 2005 to the football field basin. Certificates of Compliance were issued for the initial construction and the 2005 modifications. The stormwater improvements projects were constructed to not only address future growth of the campus,but also to address existing downstream flooding issues partially caused by upstream areas flowing through the Merrimack campus. Merrimack is filing for an Amended Order of Conditions with the Town of Andover Conservation Commission to update the Stormwater Master Plan to reflect the Volpe Center Expansion project. This submittal will reflect the modifications presented in this letter. i Comment: 3. Subcatchment M-113-1 discharges to the wetland to the northeast of the building(Wetland 2) through what appears to be two roof drain outlets,as well as in the form of overland flow in area to the east of the building,including the tennis courts. In order to more accurately assess L:\11625.00\does\letters\Stormwater RTC.doc Stormwatef Response to Comments Project No.: 11625.00 October 18,2011 Page 3 i impacts on that wetland,these areas should be modeled individually and the wetland treated as a separate design point. Response: The stormwater model has been revised to break out the areas draining to wetland 2.And these have been modeled as separate areas. The wetland is treated as a separate design point. The design intent is not to mods the existing internal plumbing associated with the roof drain systems. Comment: — 4. The building extension in the southeast corner of the existing building has roof drains along the eastern wall and looks like it should be included in the Existing Conditions Subarea M- 1B-1,not in M-1B-3A which discharges to the south. Response:Agreed. The model has been adjusted to reflect this as well as additional feedback on the plumbing system. Comment: 5. Additional information on the proposed modifications and additions to the building are needed in order for me to better understand the roof drainage areas modeled. The plans merely show the footprint of the building,but it appears that a number of existing roof drains are being redirected. I Response:The plumbing and roof drain system have not been designed for the building. The proposed stormwater design delineates areas that the plumber and architect will need to incorporate into their designs. We would suggest a condition of approval would be for the plumbing plans to be submitted for record prior to construction. Comment: 6. The hydrologic calculations should include the 1-year storm,in accordance with the North Andover Wetlands Bylaw. In addition,impacts to both the rate and the volume of discharge need to be quantified for each wetland resource,and flow paths and control points should be shown on the pre-development and post-development watershed maps. Response:The 1-yr storm has been modeled and rates and volumes provided for each resource. Flow paths have been added to the drainage figures. ■ L:\11625A 0\docsVetters\Stormwater RTC.doc i Stormwater Response to Comments Project No.: 11625.00 October 18,2011 Page 4 Comment: 7. The three pipes exiting the existing building at the concrete headwall n the south side of the building are unlabelled;what is the source of this discharge? Response:The three pipes are part of the under drain/permafrost system under the rink. They are not part ' of the roof drain system. These pipes will be re-routed under the new foundation and directed to the storm drain system.This will be included on the plumbing plans. Comment: 8. Appendix A contains rip rap sizing calculations for three outfalls;FES-1,FES-Roof-north and FES-Roof-South. However,only two outfalls are shown on the design plans and both are unlabeled and on the north side of the building. In addition,it is unclear what the basis for the discharge rates used in the calculations is;they do not correspond to the HydroCAD calculations. Response:The outlets have been adjusted based on the proposed design modifications and labels added. Outlet protection sizing has been performed based on discharge rates for the 25-year storm for FES-Roof- North and FES-Roof-South. The outlet protection was sized based on the full flow capacity of the proposed 30"drain. Comment: 9. The design plans call for replacing the existing drain line that extends south from DMH-2 in Cullen Ave. A significant portion of the flow from the proposed project will be discharged to the 15-inch drain from CB-1 and not the drain from DMH-2;has it been determined that this drain had adequate capacity to accommodate the increased flow? Response:The proposed project design will not result in increased rates or volumes of stormwater to the 15"pipe. Merrimack Facilities reports that there have not been surcharge issues with this system. Comment: 10. The proposed plan makes an effort to offset lost recharge on the site,on the basis that the soils are poor(HSG C and D)and the groundwater table is high,and that it is consistent with L:\11625.00\does\letters\Stormwater RTC.doc i Stormwater Response to Comments Project No.: 11625.00 October 18,2011 Page 5 the Stormwater Master Plan Approval by the Andover Conservation Commission. The Andover OOC does not provide any such waiver of recharge requirements,expect for the projects entailing<2,000 sf net impervious area within the Town of Andover,and I do not believe it has any bearing on wetlands permitting by the Town of North Andover. Stormwater Management Standard 3 does require that sites comprised solely of C and D soils comply with the recharge requirement"to the maximum extent practicable:,e.g,the applicant must make all reasonable efforts to meet the Standard,including evaluating alternatives that minimize impervious surfaces. The Geotechnical study conducted by McPhail Associates indicated that groundwater levels in the areas studied(to the south and west of the building)range from 2 to 4 ft below grade,suggesting that there should be some opportunity for infiltration on the site. Alternatively,I would suggest that the college might be able to provide compensatory recharge elsewhere on the campus. Response: The proposed project will attempt to provide recharge to the maximum extent practicable through the construction of rain garden systems to promote infiltration. Additional testing will be done, but initial indications are that the DEP guidelines for separation from groundwater will not be attainable. Modifications to the plan have reduced impervious area. Comment: 11. I am aware that Merrimack College and VHB recently submitted two conceptual design alternatives outlined in a letter to the Conservation Commission dated September 21,2011. The plans include several design modifications aimed at minimizing buffer zone incursion, shrinking and relocating the new parking lot and providing LID elements in the form of a rain garden. Based on the configuration and proposed grading it does not appear that any of the paved areas on the site would drain to the rain garden,therefore I presume that is purpose would be to capture and recharge roof runoff only. While this may address the requirement to provide groundwater recharge to the maximum extent practicable on the site, additional detail in the soils in that area and projected recharge volume would be needed. Response:Additional soil testing will be done,but based on record information we are not confident that there are areas on site that provide the 2'ofseparation from groundwater required by DEP. Comment: 12. The treatment train for the proposed new parking lot is comprised if deep sum catch basins and an in-line Stormceptor 450i treatment unit. The calculations use a 75%TSS removal r r L111625.00\dots\letters\Storm;vater RTC.doc Stormwater Response to Comments Project No.: 11625.00 October 18,2011 Page 6 credit for the Stormceptor unit based on the NJCAT evaluation cited on the M<ASTEP website. The JJCAT evaluation did corroborate a'75%TSS removal rate for the unit in laboratory studies;however their approved TSS removal rate for field installations is 50%. This is the removal rate that should be used in the TSS removal calculations. Response:The design has been modified to include STC 900 units. Water quality calculations are included in the Stormwater Report documenting 80%TSS Removal. i Comment: I j 13. The existing catch basins in Cullen Avenue are in-line and in series,one has a broken grate, and in all likelihood they do not have deep sumps or oil/debris hoods. Even if flow attenuation is provided further downstream in the system,the proposed increase in the flow rate discharged through these storm drains has the potential to mobilize sediments accumulated in the catch basins. Consideration should be given to moving the catch basins in Cullen Avenue(particularly C13-1 through which much of the proposed flow is discharged)offline and upgrading them with deep sumps and outlet hoods. Response:The proposed design has been modified to provide new cathchbasins with deep sumps and hoods and to eliminate the catchbasin to catchbasin connections. A Stormceptor unit is also proposed downstream of the Cullen Avenue system, i I Comment: 14. The proposed plan does not call for any drainage improvements for the existing parking area to the west of the building,even though the parking lot is being reconfigured. It is unclear j what condition the existing catch basins serving this lot are in and whether they provide any degree of water quality treatment. Response:The Monican Boulevard Relocation Project in 2004 included the replacement of the existing catchbasins with new catchbasin with deep sumps and hoods. A stormceptor has also been added downstream of this catchbasin on the easterly side of the lot to treat flows from the lot and Cullen Avenue. Comment: 15. The application does not address the fact that there is an approved Total Maximum Daily Load allocation(TMDL)for bacteria in the Shawsheen River basin,and that the Town is Aft �i LA11625.00\does\1etters\St0rmwater RTC.doc i Stormwater Response to Comments Project No.: 11625.00 October 18,2011 Page 7 j required through its Phase 2 NPDES Permit to reduce the discharge of these pollutants. To I the maximum extent practicable,the project should employ stormwater BMPs that are effective at addressing these pollutants,e.g.through filtration or infiltration. Response:As noted in Comment 17,the typical source of bacteria is from illicit connections and CSOs. As part of the plumbing design,the existing systems will be confirmed and all existing connections modified appropriately. Recharge is also being attempted on site. Comment: 16. As is indicated in the Stormwater Management Report,the proposed project entails the disturbance of more than once acre and will therefore require a Construction Stormwater Pollution Prevention Plan(SWPPP)filed under the EPA General Permit. I recommend that the Construction SWPPP be prepared by or in conjunction with the contractor selected for project construction,and that the Conservation Commission and Planning Board have adequate time to provide input prior to the plan being filed. Response:Merrimack will submit the SWPPP to the Commission and the Planning Board and address comments provided. The Commission will also have access to the site throughout construction and any concerns identified by the Commission will be addressed by the contractor and included in the active SWPPP maintained on site. Comment: 17. Measures to prevent illicit discharges from the proposed project are addressed in the Long- Term Pollution Prevention Plan. They are,however,somewhat generic and not specific to the sports facility or the nature of the operations. More specific snow storage areas need to be designated,and the use of alternative deicers should be discussed,particularly in wetland buffer areas. An Elicit Discharge Statement is also required under Standard 10 and has not been submitted. Given that the existing building is being rehabbed rather than replaced,that some portion of the interior plumbing(roof drains)appear to discharge directly to the wetland,and that the Shawsheen River has an approved TMDL for elevated levels of bacteria largely attributed to illicit discharges,the existing building should be thoroughly dye-tested to confirm that there are no illicit connections to the storm drain system. Response:As part of the plumbing design for the building,the plumbing engineer will confirm that there are no illicit connections and that all modifications to the system are designed per code. L:\1 1625.00\do Metters\Stormwa ter RTC.doc Stormwater Response to Comments Project No.: 11625.00 October 18,2011 Page 8 The college provides for snow storage in Austin Field which is adjacent to Rock Ridge Road. They are aware of and don't push any snow towards the isolated wetland adjacent to Volpe. The college also has all roads and parking lots swept of sand three times per year and removes all debris from catch basins yearly. The College uses a sand/salt mix on roads and walkways to prevent slips and falls and limits use of ice melt product primarily to exterior stairs. Merrimack College is appreciative of the input provided on the project and the willingness of the parties to meet to further discuss the project. We look forward to continuing to work with the Commission and Eggleston Environmental to make this a project that we can all be proud of. i We look forward to the opportunity to present these updates at the October 26"'Conservation Commission meeting and the November 1"Planning Board meeting. j Very truly yours, VANNASE HANGEN BRUSTLIN,Inc Christopher M. ov ,P ,LEED AP Senior Project ager Cc: Lisa Eggleston—Eggleston Environmental Jeff Doggett—Merrimack College—Chief of Staff Robert Coppola—Merrimack College—Director of Facilities Attachments: Site Plans Stormwater Report L:\11625.00\dots\letters\Stormwater RTC.doc I Transportation Land Development a Environmental ° Services 0 s Imagination I mnovatwn energy Creating results for our clients and benefits for our communities December 8,2011 -Yyl.?2Gtsw—Ha12.gen.-Bi�ustlht,_I?2_ Mr.Robert Douglas,Conservation Director Andover Conservation Commission Town Office Building 36 Bartlet Street Andover,MA 01.810 Re: Response to Peer Review of the Stormwater Design Request for Amended Order of Conditions Merrimack College Andover,Massachusetts DEP File#:90-0750 Dear Mr.Douglas and Commission Members, On behalf of Merrimack College,VHB provides the following information in response to the peer review comment letter prepared by ESS Group,Inc.on November 22,2011. The ESS Group,Inc.comments are listed below,followed by the response in italics. Comment: 1. VHB analyzed the watershed areas,soil curve,numbers,and tunes of concentration for Pre- Development and Post-Development Conditions utilizing the SCS TR-55 methodology as required. ESS Group,Inc.has reviewed the calculations and methodologies and found them to be acceptable. However the proposed watershed areas for subcatchment M-1B 31 and M- 1B 31A need clarification;specifically how the roof areas are divided and how the large landscaped area at the entrance off Cullen Avenue was divided. Additional detail should be provided to confirm these areas are accurate. Response: Existing and proposed roof areas have been delineated based on Plans of record and proposed plumbing plans. Refer to attached draft Figure B-Roof Plu inbing Plait for reference, We would suggest a Condition of Approval wotdd be for the plumbing plans to be submitted for record prior to construction. The tuatei shed divides at the large landscape area at the entrance off Cullen Avenue have been revised to be ineltided entirely within subcatchment M-1B 31 as shown on Figures 2 and 3, Existing and Proposed Conditions Drainage Areas. The grading in this area shall remain generally 101 Walnut Street Post Office Box 9151 Watertown,Massachusetts 02471-9151 617.924.1770 o FAX 617.924.2286 email:info @vhb.com www.vlib.com Response to Peer Review Comments VHB Project No.: 11625.00 December 8,2011 Page 2 unchanged in the proposed conditions. Stormwater nilloff will sheet flow dozen to the road and flow northerly towards the closed drainage system in Cullen Avenue. Revised hydrologic data, peak rates and runoff volumes associated with these.updates have been included in the attached stormzvater report revisions. As before,the results of the analysis indicate that there is no increase in peak discharge rates between the existing and proposed conditions far areas M-1B-1.1,M-1B-1.2,M- 1B-1.3,M-M-1A and M-1B-3. The design does include increase in M-1B-3A,bttt these are well within those approved by the Storrnwater Master Plan. Comment: 2. It appears as if subcatchment M-113 1.1 and M-113 11.1 should be identical but the areas are different. An explanation should be provided. Response: Based on further information from the existing/proposed phanbing plans for the Volpe Athletic Center,areas M-1B 1.1 and M-1B 11.1 have been revised to be identical. Comment: 3. ESS reviewed the proposed renovations to the football field detention basin in 2005;were these renovations completed? Response: Yes,the renovations were completed. Comment: 4. From the information provided it is not clear how the existing drainage pipes are connected to the football field detention basin. An overview of the campus which clearly shows the storm drain pipe network from the Volpe Athletic Center to the detention basin should be provided for clarity. Response: Refer to attached Figure A—Overall Drainage Plan,outlining the storm drain pipe network between the Volpe Athletic Center and the Football Field Detention Basin. Comment: 5. An overview of the drainage pipe network which illustrates how the proposed drainpipes. connect to the detention basin should also be provided for clarity. 16 Response to Peer Review Comments VHB Project No.: 11625.00 December 8,2011 Page 3 Response: Refer to attached Figure A—Overall Drainage Plan,outlining the storm drain pipe network between the Volpe Athletic Center and the Football Field Detention Basin. Comment: 6. The applicant should verify that there is no curb in the parking area near the Rain Garden 2. It appears that runoff will sheet flow from the parking area over the vegetated filter strip before reaching the rain garden,The vegetated filter strip is considered stormwater pretreatment required for rain gardens to function efficiently. Response: Correct,there is no curb along the nnajority of the south-eastern edge of the proposed parking area near Rain Garden 2(as denoted EOP on the Layout and Materials Plan). The plans inchtde a grass and gravel combination filter strip per the Massachusetts Storinwater Handbook, which requires a winintum 8 inches of gravel followed by 3 to 5 feet of sod. Adjacent to the proposed edge of pavement,the design plans include a 12-inch gravel strip followed by 20 ft.of sod prior to sheet flowing into Rain Garden 1. Comment: 7. The applicant should confirm that Rain Garden 1 is capturing clean roof runoff and therefore additional pretreatment is not required, Response: The area tributaj to Rain Garden 1 (subcatchment M-113 11.38)is comprised of clean roof runoff and n small portion of pervious area within the vicinity of the Rain Garden,therefore no pretreatment nor water gtcality uteasntres are required. Based on discussions with the peer reviewer assigned per the North Andover Conservation Commission, it was suggested that the application of Rain gardens be explored,with the understanding that they would be located in areas where minimal infiltration could be attained. Therefore,the Rain Gardens are proposed in order to provide recharge to the maximum extent practicable. It is understood that due to soil conditions,the infiltration systems will not meet the requirements set forth by DEP,however they will provide additional uneanns of water quality and,although minor,infiltration. Comment: 8. The Rip Rap Sizing Calculations found in Appendix A indicates three flared end sections (FES).The flows from Roof-North and Roof-South appear to have been obtained from the 25- year HydroCAD modeling computations.Applicant should clarify how the flow of 21.68 cfs was calculated for FES-1. e � a Response to Peer Review Comments VHB Project No.: 11625.00 December 8,2011 Page 4 Response: A flow rate of 21.68 cfs was used to size the rip-rap dimensions of FES-1 as it represents the full-flow capacity of the most restricting branch of the proposed drain line, following all upstream connections. Revised calculations have adjusted this full flow capacity to 25.62 cfs;refer to attached Rip-Rap Sizing Calculations, Comment: 9. The Drainage Diagram for Existing and Proposed Conditions indicates that Wetland 2 flows into the Football Field/Wetland Detention,the applicant should provide clarification on how this connection is trade. Response: Wetland 2 rums southerly away front the Volpe Center and discharges to an interrrrittent stream on the other side of Cullen Avenue. The stream runs southwest along the athletic fields down and around the zuest side of the football field,eventually tying into the basin. Mapping inforrntation has been compiled from the Storntzuater Master Plan,Merrhitack College Plants of Record and MassGIS. Comment: 10. Under LID Measures in the MassDEP checklist for Stormwater Report,Bioretention Cells (Rain Gardens)could be checked. Response. As noted,in response to Continent#7,the Rains Gardens are proposed in order to provide recharge to the rnaxitn tan extent practicable as well as additional nneans of water quality. As they will not meet the full requirements set forth by DEP due to soil conditions,this box was not checked. Comment: 11. The rain gardens appear to be sized adequately;however,the detail should be revised to meet the requirements within the Stormwater Manual.The soil media should be a minimum of 30-inches thick;depth to ground water should be confirmed;there are no overflow pipes on the drainage plan,however there is one shown on the detail;the plants should be appropriate for rain gardens'under drains be incorporated or is stormwater expected to infiltrate through the media?VHB should provide additional detail for the rain gardens to verify they have been designed and will be constructed appropriately. r Response to Peer Review Comments VHB Project No.: 11625.00 December 8,2011 Page 5 Response: The detail has been revised to show a 30"minimanz thickness for bioretention soil media,and to exclude the overflowltinderdrain to match the plans. Test pit data,pet formed by Soil Exploration Corp.,has been attached to this response letter in a report front Kevin Martin,P.E.dated November 4,2011. Soil information at the proposed Rain Garden locations indicate groundwater at O- ft. below existinggrade(Elev.239±). This groundwater elevation would allow for the 2-ft.separation required,however the seasonal high groundwater elevation has not been confirmed. Rain garden plantings have been proposed as shown on Sheet L-1—Planting Plan. Comment: 12. Calculations should be provided to verify the closed drainage system pipes have been sized adequately,specifically the pipe which is being called out to be replaced. Response: Refer to the attached,Storm Drain Calculations,documenting adequate sizing of the closed drainage system pipes. Per the Merrimack College Storinwater Master Plan,a design flow of 22.77 cfs would be required in the drain line running front Existing CB-2 to the Football Field Detention Basin. As capacities of the existing three segments of this drain pipe were 4.63 cfs,10.10 cfs and 3.32 cfs,it has been upsized to account for the intended master plan development,as well as to provide some additional capacity. Comment: 13. On.the site plans an area on the north side of the building is called out as Ice Storage Area. What is the purpose of this area which is located within the 100-footbuffer zone? Response: This area is utilized for the storage of excess material swept off of the hockey rink by the zamboni. The plans have been revised to include a proposed bituminous curb surrounding the existing pavement to ensure no siface runoff from this area is diverted to the existing wetlands. Comment: 14, The Long Term Pollution Prevention Plan(LTPPP)does not discuss street sweeping;in earlier submissions for Merrimack College street sweeping was part of normal operations and maintenance.The LTPPP should incorporate procedures already incorporated in the college's routine maintenance program.Has Merrimack College reviewed the LTPPP and accepted it? le Response to Peer Review Comments VHB Project No.: 11625.00 December 8,2011 Page 6 Response: The L,TPPP has been reviewed with Merrimack College and it has been noted that the campus is swept 3 tunes per year,typically around early April,nrid-May and August. Comment: 15. During construction where will soil stock piles be located?Applicant should verify that stock piles will be placed outside the 100-foot buffer zone and surrounded by erosion controls. Response: The Erosion and Sedimentation Control Manual shall be submitted along with the Stornazvater Pollution Prevention Plan(SWPPP)included for the National Pollutant Discharge Elimination System(NPDES)Permit,which documents that soil stock piles shall remain outside of the 100 foot buffer zone, The proposed silt fence barrier shozun on sheet C-3—Grading,Drainage and Erosion Control Plan shall provide additional protection of the existing Wetlands. Comment: 16. An existing chain link fence is located around the tennis courts adjacent to Wetland 2.Will the sides of the fence adjacent to the wetland remain? Response: The existing chain link fence around the tennis courts adjacent to Wetland 2 shall be removed in its entirety. Disturbed areas adjacent to Wetland 2 shall be re--vegetated with New England Conservation/Wildlife nnix per Sheet L-1—Planting Plan, Comment: 17. A portion of the proposed construction will occur within the 25-foot no disturb zone, including work around the tennis courts and placing the rip rap at the discharge points of the roof drains.The applicant should describe how construction will occur within the 25-foot no disturb zone to avoid any impact to the wetlands. Response: Work within the 25 foot no disturb zone consists of additional ontlet protection at existing drain,plantings along the northeast edge of the existing building,as well as the removal and re- vegetation of existing impervious areas(tennis courts). This work is proposed within the 25 foot banffer zone in order to provide additional erosion protection for existing onutfalls and enhance the areas adjacent to the existing Wetland 2. Constn fiction activities within the 25 font no disturb zone shall be limited to these areas and protection of the existing Wetlands shall be as required in the NPDES Pernnit per MassDEP.Additional protection of the existing Wetlands is provided per the proposed silt fence barrier. � 8 � D Response to Peer Review Comments VHB Project No.: 11625.00 December 8,2011 Page 7 Merrimack College is appreciative of the input provided on the project and we look forward to continuing to work with the Commission and ESS Group,Inc. We look forward to the opportunity to present these updates at the December 15"'Conservation Commission meeting. Very truly yours, VANNASE HANGEN BRUSTLIN,Inc rEhiistopherM` o�./e PE LEED AP Senior Projec/ ;nager Cc: Janet Bernardo—ESS Group,Inc. Jeff Doggett--Merrimack College—Chief of Staff Robert Coppola—Merrimack College—Director of Facilities Attachments: • Revised Site Plans- C-3 Grading,Drainage&Erosion Control Plan C-4 Utility Plan C-6 Site Detail 2 L-1 Planting Plan • Revised Stormwater Report Materials Figure 2—Existing Conditions Drainage Areas Figure 3—Existing Conditions Proposed Areas Hydrologic Data/Peak Flows&Runoff Volume Tables Storm Drain Calculations Rip-Rap Sizing Calculations • Figure A—Overall Drain Network • Figure B—Roof Plumbing Plan e s . Revised Storm Water Report Materials Merrimack College Volpe Athletic Center Expansion Stormwater Report Revisions Hydrologic Data Table 2 Existing Conditions Hydrologic Data Time of Design Area Curve Concentration Drainage Area Discharge Location Point (acres) Number (min) M-113-1.1 Wetland 2 2 1.2 98 6.0 M-113-1.2 Wetland 2 2 0.4 98 6.0 M-1 B-1.3 Wetland 2 2 1.2 93 6.0 M-113-IA Football Field Detention 1 L 1.3 92 6.0 M-1 B-3 Football Field Detention 1 L 1.3 83 6.0 M-1 B-3A Football Field Detention 1 L 0.9 87 6.0 Table 3 Proposed Conditions Hydrologic Data Time of Design Area Curve Concentration Drainage Area Discharge Location Point (acres) Number (min) M-1 B-11.1 Wetland 2 2 1.2 98 6.0 M-1 B-11.2 Wetland 2 2 0.4 98 6.0 M-1 B-1 1.3A Wetland 2 2 0.5 85 6.0 M-1 B-11.31, Wetland 2 2 0.3 93 6.0 M-1 B-1 1.3C Wetland 2 2 0.2 90 6.0 M-113-11A Football Field Detention 1 L 1.1 97 6.0 M-1 B-31 Football Field Detention 1 L 0.4 86 6.0 M-1 B-31A Football Field Detention 1 L 2.2 97 6.0 Merrimack College Stormwater Report Revisions Volpe Athletic Center Expansion Page 1 of 3 Peak Discharge Rates &Volumes Table 4.1 Peak Discharge Rates (cfs)&Volumes (ac-ft)-Wetland 2 Watershed Area 1-year 2-year 10-year 100-year M-113-1.1 Existing(M-1B-1.1) Rate(cfs) 2.7 3.7 5.6 7.1 Volume(ac-ft) 0.22 0.30 0.47 0.60 Proposed(M-1B-11.1) Rate(cfs) 2.7 3.7 5.6 7.1 Volume(ac-ft) 0.22 0.30 0.47 0.60 M-113-1.2 Existing(M-113-1.2) Rate(cfs) 1.0 1.3 2.0 2.6 Volume(ac-ft) 0.08 0.11 0.17 0.22 Proposed(M-1 B-11.2) Rate(cfs) 1.0 1.3 2.0 2.6 Volume(ac-ft) 0.08 0.11 0.17 0.22 M-113-1.3 Existing(M-1 B-1.3) Rate(cfs) 2.4 3.4 5.4 6.9 Volume(ac-ft) 0.17 0.25 0.41 0.55 Proposed(M-1B-11.3) Rate(cfs) 0.9 2.4 4.1 5.5 Volume(ac-ft) 0.10 0.16 0.29 0.41 Net Discharge to Wetland 2 Existing Rate(cfs) 6.1 8.4 13.0 16.6 Volume(ac-ft) 0.47 0.67 1.05 1.36 Proposed Rate(cfs) 4.4 7.4 11.7 15.1 Volume(ac-ft) 0.39 0.57 0.93 1.22 Merrimack College Stormwater Report Revisions Volpe Athletic Center Expansion Page 2 of 3 Table 4.2 Peak Discharge Rates (cfs) &Volumes (ac-ft)-Football Field Detention Watershed Area 1-year 2-year 10-year 100-year M-1 B-1A Existing(M-1B-1A) Rate(cfs) 2.5 3.7 5.9 7.7 Volume(ac-ft) 0.19 0.28 0.45 0.60 Proposed(M-1B-11A) Rate(cfs) 2.4 3.3 5.0 6.4 _.._...._.._,.........................._......................................._..__......,._Volume(ao-ft)....._.......--_..._0.19....................._.-._0.26__.....___0.41.........._...........-........0.53.._................. M-1 B-3 Existing(M-1 B-3) Rate(cfs) 1.6 2.7 4.9 6.7 Volume(ac-ft) 0.12 0.19 0.36 0.50 Proposed(M-1 B-31) Rate(cfs) 0.6 1.0 1.8 2.4 Volume(ac-ft) 0.05 0.07 0.13 0.18 M-1 B-3A* Existing(M-1 B-3A) Rate(cfs) 1.4 2.2 3.8 5.1 Volume(ac-ft) 0.10 0.16 0.28 0.38 Proposed(M-1B-31 A) Rate(cfs) 5.1 7.0 10.7 13.6 .......................................... .........._.Volume.(ac-f t)...._....._......_.._0.40.................._ 0.56 -- _ 0.87 ___ -. 1.12 Wetland 2 Existing Rate(cfs) 6.1 8.4 13.0 16.6 Volume(ac-ft) 0.47 0.67 1.05 1.36 Proposed Rate(cfs) 4.4 7.4 11.7 15.1 Volume(ac-ft) 0.39 0.57 0.93 1.22 Net Discharge to Football Field Detention Existing Rate(cfs) 11.6 16.9 27.5 36.1 Volume(ac-ft) 0.88 1.29 2.13 2.83 Proposed Rate(cfs) 12.6 18.7 29.1 37.5 Volume(ac-ft) 1.03 1.47 2.34 3.05 Master Plan approval currently maintains a 50.3 cfs credit for the 100-year storm event. Master Plan stormwater management improvements include two large extended detention basins that provide peak flow mitigation for all storms prior to discharging from the campus. Merrimack College Stormwater Report Revisions Volpe Athletic Center Expansion Page 3 of 3 Project Name: Volpe Center Expansion Proj. No.: 11625.00 Project Location: North Andover, MA Sheet: 1 of 1 Calc'd By: NJS Date: October 2011 Revised: JWK Date: December2011 Tw>_0 5D Tw<0.5Do 3Do <Do } 5(min.) W-Do+0.4La Z W=Do+La Do j �,_ La -I FES-1 Do= 30 in. 3Do= 90 in. Tw<0.5Do Q= 25.62 cfs W= 12.5 ft. La= 10.0 ft. W(2:1)= 17.5 ft. Rip-Rap Dimensions: 3Do= 7.5 ft. d50= 6 in. La= 10.0 ft. Z= 12 in. W= 17.5 ft. FES-Roof-North Do= 8 in. 3Do= 24 in. Tw<0.5Do Q= 6.3 cfs W= 10.7 ft. La= 10:0 ft. W(2:1)= 12.0 ft. Rip-Rap Dimensions: 3Do= 2.0 ft. d5o= 6 in. La= 10.0 ft. Z= 12 in. W= 12.0 ft. FES-Roof-South Do= 10 in. 3Do= 30 in. Tw<0.5Do Q= 2.3 cfs W= 10.8 ft. La= 10.0 ft. W(2:1)= 12.5 ft. Rip-Rap Dimensions: 3Do= 2.5 ft. d50= 6 in. La= 10.0 ft. Z= 12 in. W= 12.5 ft. Rip Rap\\MAWALD\Id\11625.00\ssheets\Rip Rap Sizing Figures I1 h1AWALD11d111625.001radVd\EngTX-FIGURE.dwg SALEM ) ( LEGEND (PUBLIC - 110' WIDE ROUTE 125 ROUTE 114) TUR1Vp ; xFt-loo IKE SUBCATCHMENT DRAINAGE I AREA DESIGNATION 1\Fi-Im WETLAND 1 310A { I-1o5 �_ � -� - q 1 POND WF 2 W-110 nz ' \�; u' PNF2-95 � �n-moo, HE g2_I91� -16 WETLAND li, qF2-99 �- _� M — . _ qF2 DESIGN POINT -� xF2-IO5 qFZ-m _ q t wrz . - ___ !" 4F2 =245 24' 45 I% \ =24521 DRAINAGE AREA BOUNDARY .. i 4 6,069 S.F. '\ (10 699 ACRES) 70A t qF — 100" BUFFER ZONE I E E=24525' _. qF2-I13 3 1 OA WETLAND BOUNDARY 4-220 4-219 M-1B J .� SOIL TYPE BOUNDARY M-1B VOLPE ATHLETIC COMPLEX 1.2 1 </ FFE 245.15 ffi —__w__.y___—► I ' j"F2 — TIME OF CONCENTRATION j 1 E 245.19' 1�1 FLOW LINE C VA1Ai M= fts emu Emm FFE-24 W2-1 NRCS SOIL CLASSIFICATIONS (HSG) ® 24522' ® ° ® �a FFE_24 SoRr°:<rn ,�s2 M-1B ? FFE?5 UE 2452 ® ®FS / AW 1.3 °� 70/� RIDGEBURY FINE SANDY LOAM 3� `,, i ' /// ROpF /• X41- HSG C y ' ° 2_0 qFZ n2 LOAM — 240.5 72A G � . c7"'R y. 0 I HS D • M-1B M-1B 72A WOODBRIDGE FINE SANDY LOAM e _ 310A HSG C ' `FLEC.fiH CULLEN AVENUE _... - 70A - / , 1 TO FOOTBALL FIELD DETENTION AREA Figure 2 December 2011 Existing Conditions Drainage Areas 1L Volpe Athletic Center Expansion 0 40 80 Feet N.Andover,Massachusetts IIMAWALDftl1625.0fta NdlEnglPR-FIGUREAvig SALEM (PUBLIC ) ( AI LEGEND — 110' WIDE ROUTE 125 ROUTE 114) T f 4, —s_- AREA SUBCATCHMENT DRAINAGE AREA DESIGNATION WETLAND 1 • i 1 iI .o 1 POND t S 3 III r t WETLAND' WTI I �,f®- •- i\� _I -, DESIGN POINT imew < 1 �: _ i _ ® � s ®, 7--n-7-1 ( .4 A: sv y�, i®6 -- r�j.=/r if; i�l 'i t ®—`,_ i _ ii✓/i.+i i ri�rt>� �Fy \� , ,x, a RAIN GARDEN M 1B a 11 1 M N 11.3 f 1 4" t DRAINAGE AREA BOUNDARY f _ EXIS ri NG� - A VOLP E C ENTER 100" BUFFER z ZONE M-1B lip 1` M-1B j WETLAND BOUNDARY t ® 1 4-220 4-219 3 11 i,�.,_, �, # — SOIL TYPE BOUNDARY , b° , r j ✓ 1 s 1 j. ✓�//l✓�%, ._ �'_3® ® ® ��3 ✓ %t 7 j -° — TIME OF CO NCENTRATION EN N f r I �' T E`�•�'i.. Y�l4, M-1B til�!�L��i�..3�/ll�%✓��rl� �m '._{»i`' r. / - yt y��-:., ® ,.- FLOW LINE M` {p r £ t t 4th r =° C✓.�%l�✓1/�Ylil%/��t< — i. `s�rt t 1 2 a 'iROPOS ` r ,r,V®L ?E4 PROPOSE® ?11.3 . G z # R � NRCS SOIL CLASSIFICATIONS HSG YOLPE'iCEIVI-ER �` t ,! /- t F� �,��TER XP,4 = 1 RY FINE SANDY LOAM f. E - NS O ® RIDGEB >T}' i' PANS�OIW ,:,: f l� 3 N I -,f ///�� HSG C U rS _ .4 ' N �I _\' - r M-1B n I � r LOAM �3 M-1B ! i d i3 ��; � C�� 72A HSG D AN s s ,� �— �•� �, tiro a%— -�z \ 31 , 1 WOODBRIDGE FINE SANDY LOAM �� r HSG C - - - .y -- I \ r — 1[ 1 - - CULLEN AVEN - _® ® . �. _r M s y t .. L TO FOOTBALL '} _ 1 FIELD DETENTION AREA Figure 3 December 2011 Proposed Conditions Drainage Areas 1L I Volpe Athletic Center Expansion 0 40 80 Feet N.Andover,Massachusetts Project: Volpe Athletic Center Expansion-Merrimack College Project p: 11625.00 Location: North Andover,Massachusetts Sheet: 1 of 1 Calculated By: JWK Date: December 2011 - Title: Storm Drain Calculations per Stormcad Model Conc. System DESIGN CAPACITY UPPER LOWER Description Start Stop Area C System CA Time Intensity Q Manning's Diameter Slope Q V Length Rim EGL HGL Invert Rim EGL HGL Invert Headloss Node Node (acres) - (acres) (min) - I (cfs) n (in) (ft/ft) (cfs) lift/s) (ft) (ft) (ft) (ft) (ft) (ft) (ft) - (ft) P-CB-Al CB-Al WQU-A1 0.18 0.82 0.15 5.0 6.0 0.91 0.011 12 0.011 4.51 4.49 148 242.25 239.55 239.40 239.00 241.40 237.92 237.60 237.30 1.80 P-EX-CB3 EX-CB3 WQU-A1 0.17 0.86 0.14 5.0 610 0.86 0.011 8 0.173 5.95 12.12 15 241.81 240.53 240.34 239.90 241.40 239.37 237.48 237.30 2.86 P-WQU-A1 WQU-Al EX-CB2 - - 0.29 5.5 5.9 1.73 0.011 12 0.044 8.80 8.71 55 241.40 237.79 237.56 237.00 237.67 235.47 235.36 234.60 2.20 '.. P-RD-A RD-A CO-Al 1.19 0.90 1.07 5.0 6.0 6.45 0.011 12 0.026 6.80 8.21 23 242.20 240.99 239.94 238.00 243.00 240.45 239.40 237.40 0.54 '.. P-CO-Al CO-Al DMH-A1 - - 1.07 5.0 6.0 6.44 0.011 12 0.024 6.58 8.20 45 243.00 239.87 238.82 237.40 242.90 238.82 237.77 236.30 1.05 P-RD-B RD-B CO-A2 0.59 0.90 0.53 5.0 6.0 3.22 0.011 12 0.040 8.42 10.01 15 245.20 239.15 238.77 238.00 243.00 238.61 238.33 237.40 0.44 P-CO-A2 CO-A2 DMH-A1 - - 0.53 5.0 6.0 3.22 0.011 12 0.046 9.01 10.53 24 243.00 238.55 238.17 237.40 242.90 238.03 237.77 236.30 0.40 '.. P-DMH-A1 DMH-A1 EX-CB2 - - 1.60 5.1 6.0 9.63 0.011 15 0.019 10.62 9.80 124 242.90 238.38 237.37 236.20 237.67 236.31 235.36 233.80 2.02 P-EX-CB2 EX-CB2 DMH-A2 - - 1.89 5.7 5.9 11.19 0.011 24 0.012 29.05 8.64 288 237.67 235.40 234.90 233.70 234.12 232.00 231.51 230.30 3.39 P-DMH-A2 DMH-A2 DMH-A3 - - 1.89 6.2 5.8 10.98 0.011 30 0.003 26.48 5.14 201 234.12 231.73 231.32 230.20 234.76 231.14 230.75 229.60 0.57 P-DMH-A3 DMH-A3 FES-1 - 1.89 6.9 5.6 10.73 0.011 30 0.003 25.62 4.99 179 234.76 231.02 230.63 229.50 234.00 230.51 230.10 229.00 0.53 P-CB-B1 CB-131 DMH-B1 0.04 0.90 0.04 5.0 6.0 0.21 0.011 12 0.011 4.34 2.86 94 239.20 236.45 236.39 236.20 238.50 235.58 235.57 235.20 0.82 P-CB-B2 CB-B2 DMH-B1 0.17 0.65 0.11 5.0 6.0 0.68 0.011 12 0.011 4.44 4.10 9 238.30 235.77 235.64 235.30 238.50 235.67 235.57 235.20 0.08 P-DMH-B1 DMH-B1 DMH-B2 - - 0.15 5.5 5.9 0.88 0.011 12 0.011 4.36 4.34 56 238.50 235.64 235.49 235.10 237.90 235.27 235.24 234.50 0.26 P-DMH-B2 DMH-B2 DMH-B3 - - 0.15 5.8 5.8 0.87 0.011 12 0.013 4.78 4.63 31 237.90 235.25 235.22 234.40 237.80 235.23 235.22 234.00 0.01 '.. P•CB-B3 CB-B3 DMH-B3 0.26 0.71 0.19 5.0 6.0 1.13 0.011 12 0.007 3.56 4.02 14 237.90 235.52 235.35 234.90 237.80 235.43 235.19 234.80 0.15 '.. P-EX-CB-B EX-CB-B DMH-B3 0.80 0.86 0.69 5.0 6.0 4.18 0.011 15 0.005 5.12 4.65 40 238.27 236.04 235.70 234.84 237.80 235.85 235.49 234.66 0.21 '.. P-DMH-B3 DMH-B3 WQU-B1 - - 1.03 5.9 5.8 6.03 0.011 15 0.010 - 7.63 6.90 10 237.80 235.21 234.69 233.70 238.30 235.13 234.50 233.60 0.20 Tl \\, W Wgj.<;;, t p $g j-I�$ � t �m +f mrr �ti `-� O v) ,j,� Y� j�axitbr�CY�,� u 'A1 � 1--•,� (j,ttt �x .�,�,T `� Q � � a.( WW c fC \f OR r fp � � i¢,�N {ZY2��J C7� in � f _ �,- �Jj��','.}�;4ch: � t�<R // w U Z cat (� ! E` '-.! Ca. ( co \� W t Seczs�r $ ;� v -c.3 �.✓ J'aac�d � V � - S t ..�} tt�t> c E � �cy �.L�:rca � 7 tz \7 �- n U tf !i E1 ° „ Q cu / O '�� -..,� r s t f y lJ l/ a.tz-. S n � Q \J € c> } '19 sort t••i i > 7 Xi Oy \. 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E EXISTING ROOF DRAIN EXIT(S) TO BE LOCATED PICKED UP WITH NEW EXIT 2 �-- ROOF PLUMBING PLAN , Volpe Athletic Center EXIT 1 _ - Merrimack College 1 r { z North Andover, MA Transportation ' Land Development ° Environmental S e r v i c e s 0 i imagination innovation energy Creating results for our clients and benefits for our communities December 22,2011 _Vanasse ffa.Wn Rru.ctlin, Tne Mr.John Simons,Chairman North Andover Planning Board 1600 Osgood St. North Andover,MA 01845 Mr.Louis Napoli,Chairman North Andover Conservation Commission 1600 Osgood Street,Suite 2-36 North Andover,MA 01845 Re: Response to Stormwater Peer Review Comments DEP File#:242-1531 Volpe Athletic Center Expansion—Merrimack College North Andover,Massachusetts Dear Chairmen,Board Members and Commissioners, On behalf of Merrimack College,VHB provides the following information in response to the peer review comment letter prepared by Eggleston Environmental on October 26,2011. The Eggleston Environmental comments are listed below,followed by the response in italics. Comment: 1. Additional information regarding the scope of the 2005 modifications to the Stormwater Master Plan,as well as copies of the Certificates of Compliance referenced in the response letter should be provided to the Commission. Response: Based on further conversations with the College,it is understood that Certificates of Compliance have not been issued for the drainage improvements,as the Order remains open. It is understood that a sitewalk was conducted on November 16"'to observe the constructed Stormwater master plan improvements. Please refer to the attached plans of the 2005 stormwater modifications at the"Athletic Game Field". 101 Walnut Street Post Office Box 9151 Watertown, Massachusetts 02471-9151 617.924.1770 a FAX 617.924.2286 L:\11625.00\does\letters\2011-12-21 EE Response to Volpe Center Comments#2.doc email: Info @vhb.com www,vhb.com Stormwater Response to Comments Project No.: 11625.00 December 22,2011 Page 2 Comment: 2. In response to my comment#5,VHB has indicated that the plumber and architect will need to incorporate the stormwater drainage areas used in the design into the design of the building,and suggested that the submission of the plumbing plans be made a condition of approval.Instead of asking the Town boards or their agents to verify the design,I suggest that this be made a requirement of the as-built certification provided by a registered Professional Engineer at the completion of construction. Response: Agreed, this requirement can be added to the Order of Conditions. Comment: 3. The proposed plan calls for two rain gardens to be located along the eastern edge of the project site;rain garden#1 would receive runoff from a portion of the new roof area,and rain garden#2 would receive runoff from a portion of the new parking area.The primary purpose of the rain gardens is to provide some degree of recharge on the site,despite the relatively low-permeability soils,and to retain the runoff within the drainage area to the onsite wetlands.Rain garden#2 will also provide treatment of the pavement runoff.VHB has noted that the 2 ft of separation called for in the DEP guidelines may not be attainable on the site, and I concur that this may well be the case.The DEP guidelines also do not permit infiltration structures within 50 ft of the wetlands,and both rain garden locations are located within the 50-ft wetland no-build zone.However,given that this is a redevelopment project and the areas proposed for the rain gardens seem to be the only feasible locations for infiltration on the site,I do not believe that strict compliance with the DEP guidelines is either necessary or preferable.Unless they are totally below the normal groundwater level,the proposed rain gardens will provide some degree of recharge during low groundwater periods,and will help to attenuate runoff flows to the wetland.In addition,the vegetative uptake coupled with infiltration and/or filtration in rain garden#2 will provide water quality enhancement for the pavement runoff.If the groundwater is at or near the bottom of the basins they may need to be constructed and planted as pocket wetlands;while the groundwater recharge would be minimal they would still provide recharge to the onsite wetlands and water quality treatment for the pavement runoff. Response: Agreed,based on discussions with the peer reviewer,it was suggested that the application of Rain gardens be explored,with the understanding that they would be located in areas where nininial infiltration could be attained. Therefore,the Rain Gardens are proposed in order to provide recharge to L:\11625.00\dots\letters\2011-12.21 EE Response to Volpe Center Comments#2.doc Stormwater Response to Comments Project No.: 11625.00 December 22,2011 Page 3 the maximum extent practicable. It is understood that due to soil conditions,the infiltration systems will not meet the requirements set forth by DEP;however they will provide additional means of water quality and infiltration. Test pit data,pet formed by Soil Exploration Corp.,has been attached to this response letter in a report from Kevin Martin,P.E.dated November 4,2011. Soil information at the proposed Rain Garden locations indicate groundwater at 4-ft, below existing grade(Elev.239±). This groundwater elevation would allow for the 2-ft. separation required,however the seasonal high groundwater elevation has not been confirmed. Comment: 4. It is not clear how the roof drainage from area 113B will drain to rain garden#1 as no roof drain connection is shown.If gutters or roof drains are not proposed for that part of the building addition I would suggest adding dripline trenches to further enhance infiltration. Response: Runoff from the portion of the building included in area 11.3B shall be collected in a roof drain and discharged via a downspout to Rain Garden 1. The proposed downspout location along with associated stone protection has been added to the plans. Comment: 5. Additional pretreatment,e.g.a filter strip,stone diaphragm,sediment forebay,or some combination thereof,is needed prior to the pavement runoff entering rain garden#2. Response: The plans have been updated to include a grass and gravel combination filter strip per the Massachusetts Stormwater Handbook,which requires a minimum 8 inches of gravel followed by 3 to 5 feet of sod. Adjacent to the proposed edge of pavement,the design plans shall include a 12-inch gravel strip followed by 20 ft. of sod prior to sheet flowing into Rain Garden 1. Comment: 6. The rain garden detail shown on Sheet C-6 is not consistent with the proposed design,which calls for an overflow swale and no landscape drain.The detail should also specify the bioretention soil mix.Additional detail on the proposed plantings for the rain gardens will need to be provided;I do not believe they were included on the landscape plan submitted to the Planning Board.Final determination of the plantings should be based on the groundwater hydrology when the basins are excavated. L:\11625.00\does\letters\2011-12-21 EE Response to Volpe Center Comments#2.doc Stormwater Response to Comments Project No.: 11625.00 December 22,2011 Page 4 Response: The Rain Garden detail on Sheet C-6 has been revised to reflect the design shown on the plans by removing the landscape drain. Sheet L-1—Planting Plan has been updated and provided,detailing proposed plantings at the Rain Gardens. Refer to Attachment A: Section 329500— Bioretention Areas for clarification on the bioretention soil mixture. This specification section shall be included in the project documents. Comment: 7. Per the attached 8/31/11 NJCAT certification letter,the proposed STC-900 units have an approved TSS removal rate of 50%for field(vs.laboratory)installations,not 75%as is used in the TSS calculations. Hence,the treatment train for the lower portion of the new parking lot, comprised of deep sump catch basins and the Stormceptor units,does not meet the 80%TSS removal called for in the DEP regulations.I believe this is offset at least to some extent by the net improvements in water quality provided by the proposed upgrades to the existing drainage system in Cullen Ave.The college does also sweep the streets and parking areas several times per year,which will help with TSS removal. Response: According to the manufacturer's sizing criteria,both STC-900 Units have been sized via the PCSWMM Stormceptor Sizing program which documents TSS Removal Efficiencies for WQU-A1 and WQU-A2of 91%and 80%,respectively. Sizing was based off of providing a minimum TSS Removal Efficiency of 80%for the required water quality volume(0.5"runoff depth)relative to each unit's tributary impervious area,per Standard 4 of the Massachusetts Stormwater Handbook. However,based on the NJCAT cert�flcation letter dated August 31,2011,the Stormceptor STC proprietary separators have been certified by NJDEP with a 50% TSS removal rate based on the criteria provided therein, therefore,the assumed TSS Removal efficiency rates have been adjusted. As shown on the attached, Weighted Average TSS Removal Calculations,a majority of the proposed parking lot(±6,745 sf.of impervious area)is diverted via sheet flow runoff to Rain Garden 2,which, with the use of the gravel/sod filter strip shall achieve treatment train of 90%TSS Removal per MassDEP. The remaining portion of new impervious area associated with the new parking lot and additional parking along Cullen Avenue(±4,535 sf of impervious area)is collected in the closed drainage system and diverted to the STC-900 unit(WQU-A1)which shall achieve a treatment train of 64% TSS Removal per the updated NJCAT certification and consequently,MassDEP. By pet forming a weighted average of these treatment trains based on the impervious areas,a removal efficiency of 80% can be attained for the new impervious area proposed as part of the project. As noted in the comment above,the project treats existing parking/road areas as well as the proposed new lot. Overall,the Stormceptor STC-900(WQU-B1)treats approximately 1.5-acres of impervious 0 LA11625,00\docs\letters\2011-12-21 EE Response to Volpe Center Comments#2.doc Stormwater Response to Comments Project No.: 11625.00 December 22,2011 Page 5 area(±1.7-acres of total area),roughly 1-acre of which is the existing parking lot and roughly 0.33-acres of which is part of the proposed building expansion. Considering that the project treats a significant portion of existing impervious areas,a majority of the proposed impervious area is comprised of roof runoff,and as a weighted TSS removal efficiency of 80% can be attained for the additional impervious area requiring treatment, VHB believes that sufficient measures are proposed in order to meet the MassDEP requirements to the maximum extent practicable. In addition to the Eggleston Environmental review, the proponent has also received comments from the Town of Andover Conservation Commission's peer reviewer (ESS). The Andover correspondence and related plan updates are appended to this letter. Merrimack College is appreciative of the additional input provided on the project and we look forward to the opportunity to present these updates at the January 17th Planning Board meeting Conservation Commission meeting and the January 25th Conservation Commission meeting. Very truly yours, VANNASE HANGEN BRUSTLIN,Inc ristopher M.LovettICE,Ll1D AP Senior Project Mana �r .1 . Cc: Lisa Eggleston—Eggleston Environmental Jeff Doggett—Merrimack College—Chief of Staff Robert Coppola—Merrimack College—Director of Facilities Attachments: • Stormwater Improvements—Football Basin-Construction Drawings • Geotechnical Memorandum • Updated Site Plans • Andover Peer Review Correspondence D D L:\11625.00\does\letters\2071-72-21 EE Response to Volpe Center Comments#2 doc Eggleston Environmental January 10, 2012 North Andover Planning Board 1600 Osgood Street North Andover, MA 01845 Attn: Judy Tymon, Town Planner North Andover Conservation Commission 1600 Osgood Street North Andover, MA 01845 Attn: Jennifer Hughes, Conservation Coordinator RE: Stormwater Management Review Merrimack College, Volpe Center Expansion Dear Ms. Tymon and Ms. Hughes: I have received and reviewed the December 22, 2011 Response to Peer review comments and revised plans and calculations from VHB, Inc. on the above-referenced project. The revised submittal satisfactorily addresses most of the comments in my previous letters of September 28, 2011 and October 26, 2011, however I do have the following comments: 1. It is still not clear whether the work called for in the Stormwater Master Plan, including the 2005 modifications, has been satisfactorily completed and the football field detention basin to which this project discharges functioning as designed. The response indicates that a Certificate of Compliance has not yet been issued, but have as-built plans and an engineer's certification been submitted, or can the Andover Conservation Commission indicate whether they are satisfied with that portion of the project? 2. Figure A in the December 8, 2011 Response packet submitted to the Andover Conservation Commission indicates that there are two wetland areas within the Town of North Andover near the terminus of the two drain lines that convey flow from the Volpe Center site to the football field detention basin. It is not clear whether these are jurisdictional wetlands and, if so, why they have not been included in the NOI filing. At least one of the drains is being replaced with a larger capacity pipes and outlet protection device in close proximity to the wetlands. 3. Figure A (referenced above) also calls for a portion of the drain from existing catchbasin B3 to be replaced/upsized and a new riprap apron installed, however I do not believe that was previously discussed as part of this project. 32 Old Framingham Rd Unit 29 Sudbury MA 01776 tet 508.259.1137 fax 866.820.7840 Volpe Athletic Center, Technical Review January 10, 2012 2 4. Maintenance of the grass and gravel filter strip upgradient of Rain Garden 2 should be included in the O&M Plan. I would suggest using a larger stone in the trench to keep it in place, as it is likely that snow from the parking lot will be plowed across it. If that is the case, the grass filter strip will also need to be periodically raked to prevent accumulated solids from entering the rain garden. 5. The composition of the bioretention soil mix for the rain gardens should be specified on the design details. Once again, I appreciate the opportunity to assist the North Andover Planning Board and Conservation Commission with the review of this project, and hope that this information is suitable for your needs. Please feel free to contact me if you or the applicants have any questions regarding the issues addressed herein. Sincerely, EGGLEsmN ENVIRoNwi'rN7-AL. Lisa D. Eggleston,P.E. Tvansporrtat ion .and Development a a Environmental - ° ° Services 0 a imagination i I energy Creating results for our clients andbenefits for our commnniAes January 17,2012 Mr. Robert Douglas,Conservation Director Andover Conservation.Commission Town Office Building 36 Bartlet Street Andover,MA 01814 Re: Response to Peer Review of the Stormwater Design. Request for Amended Order of Conditions Merrimack College Andover,Massachusetts DEP File#:90-0750 Dear Mr.Douglas and Commission Members, We appreciate the opportunity that we had to present the updates to the design of the Merrimack College Volpe Center Expansion at the public hearing on January 11"and are pleased that we were able to confirm the stormwater bank for the project. On behalf of Merrimack College,we are providing the following additional information in response to the three outstanding items that were identified at the public hearing. The comments are listed below,followed by the response in italics: Comment: 1. It was requested that the existing,"CB2"at the northerly end of the softball field be replaced with a manhole. Response: The plans have been nrod�ied to note that the Existing CB2 shall be converted to a.inanJ ole and a new CB will he installed to replace its collection functions. This is docilinented on the attached sheet G3 Grading Drainage and Erosion Control Plait, Comment; 2. Groundwater information was requested in the area of the rain gardens and a question was raised about the effectiveness of the water quality treatment. 101 Walnut Street Post Office Box 9151 Watertown, Massachusetts 02471-9151 617.924.1770 a FAX 61 Z924.2286 \\iIAINALD\ld\11625.00\does\letters\2012.1.16_ttesponseto Andover Peer Reviemdoc email: info @vlib.com lof4 www,vhb.com Response to Peer Review Comments VHB Project No.: 11625.00 January 17,2012 Page 2 Response: Soil Exploration Corr per formed boring tests in late October 2011. The boring logs are attached,and indicate groundwater at elevation 239.0(B-10). Rain Garden 1 (RG-1)receives roof runoff only(refer to attached Figure 1--Rain Garden Areas for Water Quality). Since this is considered clean under the DEP Stormwater Standards,RG1's primary purpose is recharge, The bottom of RG1 is at elevation 242 or 3'above observed groundwater. Rain Garden 2(RG-2)receives runoff from a small area(6,195 sf of impervious)from the sidewalk and parking lot on the southerly end of the building. It provides water quality treatment through a 12" gravel filter strip upstream-of the rain garden,and a 20 ft,wide sod strip designed to filter runoff(in comparison with the S"gravel strip and 3-5 feet of sod as required by DEP). The basin has been redesigned to raise the bottom to 242.25 and extend the limits,and will provide 1.5 times the required water quality va7iitire at a depth of 6". TJzis increases the vertical-W—(ration to;observed groundwater to approximately 3.25 ft.from the bottom of the basin(0.5 ft.from the bottom of the 30"planting media profile to support the rain garden—dote:DEP minimum is 24"of soil medium). While not in compliance with the DEP required 2'separation,the design is developed to meet the standards to the maximum extent practicable. Additional groundwater monitoring data was obtained fiorn the nearest U.S.Geological Survey (L1SGS)monitoring station located in Andover,MA,and is included in the attachments. Per the data provided,the annual high groundwater levels measured at the monitoring station(analyzed from January 2000 to January'2012)have been on average of 0.6 ft. higher than the groundwater levels measured at the time of the Volpe Athletic Center Test Pits. Applying this to the October groundwater level measurements at the Rain Gardens would provide an estimated annual high groundwater elevation of 239.6,which would intrude approximately 0.1 ft. into the proposed Rain Garden planting media profile but remain 2.6'below the bottom of the basins. We respectfully request that-the modified design be approved given the following: 1. The RG2 is located in North Andover,and was included to address concerns that the hydrology to the adjacent wetland be maintained. 2, Given the limited volume draining to the rain garden and the capacity of the importing media to accept this,the first flush of runoff will not result in standing 7vater,Even with standing water,water quality treatment world be provided. s \\R4AWALD\ld\11625.00\does\letters\2012-1-16_Response to Andover Peer tteeiew.doc 2of 4 Response to Peer Review Comments VHB Project No.: 11625.00 January 17,2012 Page 3 3. The previous RG design(which has been itrrproved)ivas found acceptable and in compliance with the DEP Stortnwater Management Standards to the inaxinittin extent practicable by both the North Andover and Andover peer review constdtants. Comment: 3. The Commission requested that a protocol be developed to document that the stormwater management system is functioning as per the approved design. Response: Merrimack proposes that a metering prograttt be developed for confirmation of the pond functionality. Within 6-months of the completion of a project increasing imperviotis area by greater than 5,000sf within the watersheds of the Football Field and Elnt Street detention areas,a flozo meter shall be installed within the outlet control structure of the appropriate pond. The meter shall be left in place and record data tnttil a storm of at 2.5"has occurred. A report shall be submitted to the Andover Conservation Report suantnarizing the metering data and consistency with the approved master plan design. The initial monitoring will be pet forined for both basins upon the col,tpletion of the construction of the Volpe Center Expansion. We look forward to the opportunity to present these updates at the January 25th Conservation Commission meeting. Very truly yours, VANNASE HANGEN BRUSTLIN Inc t istopher�Ivl.L tt,PE,LEED AP Senior Pr6cctA ager Cc: Janet Bernardo—ESS Group,Inc. Jeff Doggett—Merrimack College—Chief of Staff Robert Coppola—Merrimack College—Director of Facilities 1� e \\MAINALD\Id\II625.00\does\letters\20124-1b.Response to Andover Peer Reviecv.doc 3of 4 Response to Peer Review Comments VHB Project No.: 11625.00 January 17,2012 Page 4 Attachments; • Revised Site Plans: C-3 Grading,Drainage&Erosion Control Plan C-4 Utility Plan • Soil Exploration Corp Boring Logs • Figure 1—Rain Garden Areas for Water Quality • Revised Water Quality Volume Calculations • USGS Groundwater Levels&Locus Map B \\MAWALD\ld\11625.00\dots\letters\2012-1-16_Response to Andaver Peer Reviemdoc 4of 4 '1 m i .YES I� k• -- 4 nH t C� y�ppyyy��sss CL CL ip it 4 3` Ly �III 1 L s 111 Q W Z N 0'Q, Ill+i Q� ZW j5 151 co 'a' O WG. u� ti 41�:t£W W,s` k it ro op \ rI \ Soil Exploration Corp. g Volpe Center Expansion GeotechnicalDrillin BORING B-1 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4,2011 Ground Elevation: 243 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 27,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 27,2011 10/27/1 5 ft n/a Upori Completion Driller: GG Soil En ineer/Geologist: KM Depth Casing Sample Visual Identification Ft. bl/R No. Pen/Rec Depth Blows/6" Strata of Soil and/or Rock Sample Organic Topsoil 1 1 6" 0-110" 3-5 1' 1A 3" 1'0"-2'0" 7-9 Brown,fine to medium Sand,little silt(FILL) 2 14" 2'0"-4'0" 7-9-9-11 2' Brown,Fine Sand,some silt,trace gravel 5 3 16" 5'0"-7'0" 11-12-12-14 Same,wet (GLACIO-FLUVIAL) 10 4 2" 10'0"-10'4" 60/4" 10' Same,with cobbles and boulders. 15 5 13" 15'0"-17'0" 13-21-17-22 Grey, fine to medium Sand & Silt, trace gravel, trace clay, wet (TILL) 19' 20 Refusal at 19 ft 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff, 30+Hard. And 35%to 50% HAMMER FALL IN 30" NE Soil Exploration Corp. g Volpe Center Expansion GeotechnicalDrillin BORING B-2 Groun&vater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4,201 1 Ground Elevation: 242 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 27,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 27,2011 10/27/1 5 ft n/a Upon Completion Driller: GG Soil Engineer Geolo ist: KM Depth Casing Sample Visual Identification Ft. bun No. Pen/Ree Depth Blows/6" Strata of Soil and/or Rock Sample Organic Topsoil 1 1 6" 0-110" 3-5 1' 1A 6" 1'0"-2'0 5-5 2' Dark Brown,loamy Fine Sand&Silt,trace organics(SUBSOIL) 2 16" 2'0"-4'0" 5-5-6-6 Grey-Brown,mottled,fine to medium Sand&Silt,little gravel 5 3 15" 5'0"-7'0" 5-7-9-10 Same,wet (GLACIO-FLUVIAL) 9' 10 4 10" 10'0"-12'0" 16-22-25-26 Brown-Grey, fine to medium Sand& Silt, little gravel, cobbles wet(TILL) 15 5 2" 15'0"-15'4" 75/4" Fractured,weathered rock in spoon 17' Refusal at 17 ft Groundwater table at 7'0". 20 25 30 35 l Notes: Hollow Stem Auger Size-4-1/4" l Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff 30+Hard. And 35%to 50% HAMMER FALL IN 30" � z �-ORYN �oG SHEEr3 Soil Exploration Corp. G Volpe Center Expansion eotechnical Drilling BORING B-3 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4,2011 Ground Elevation: 240 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 28,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 28,2011 10/28/1 4 ft n/a Upon Completion Driller: GG Soil En ineer/Geologist: KM Depth Casing --- Sample Visual Identification Pen/Ree Ft. butt No, Depth Blows/6" Strata of Soil and/or Rock Sample Topsoil 1 6" 0-110" 2-3 1 1 A 6" 1'0"-2'0" 3-4 1' Rust Brown,loamy,Fine Sand&Silt,roots(SUBSOIL) 2 12" 2'0"-4'0" 3-4-4-5 Same(SUBSOIL) 4' 5 3 14" 5'0"-7'0" 5-7-7-9 Grey-Brown,mottled,fine to medium Sand&Silt, trace gravel, wet (GLACIO-FLUVIAL) 10 4 2". 10'0"-10'2" 75/2" 91 Weathered Bedrock 11' Refusal at 11 ft 15 20 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff, 30+Hard. And 35%to 50% HAMMER FALL IN 30" -, _ST ® I� G. : STREET 4 Soil Exploration Corp. Volpe Center Expansion Geotechnical Drilling BONG B-4 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4,2011 Ground Elevation: 242 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 27,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 27,2011 10/27/1 5 ft n/a Upon Completion Driller: GG Soil En ineer/Geologist: KM Depth Casing Sample Visual Identification Ft. bun No. Pen/Ree Depth BlowsW' Strata of Soil and/or Rock Sample Topsoil 1 5" 0-110" 3-5 1 1A 4" 1'0"-2'0" 4-5 1' Tan,fine to medium Sand,little silt (FILL) 2 13" 2'0"-4'0" 4-5-5-6 Same,dry(FILL). 3 8" 4'0"-5'0" 2-2 4' Black Organic Silt(TOPSOIL) 5 4 13" 5'0"-7'0" 11-17-20-21 5' Grey,fine to medium Sand,some gravel,little silt,cobbles,wet (TILL) 10 5 16" 10'0"-12'0" 12-24-24-27 Brown,fine to medium Sand&Silt,trace gravel,wet(TILL) 13' 15 6 15'0"-15'4 75/4" Weathered Bedrock 17' Refusal at 17 ft 20 25 30 35 Notes: Hollow-Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff, 30+Hard. And 35%to 50% HAMMER FALL IN 30" TEST=B� I�OG = SHEET -5 Soil Exploration Corp. Volpe Center Expansion Gcotechnical Drilling BORING B-5 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4,2011 Ground Elevation: 242 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 27,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 27,2011 10/27/1 5 ft n/a Upon Completion Driller: GG Soil En ineer/Geologist: KM Depth Casing Sample Visual Identification Ft. bvft No. Pen/Re- Depth Blows/6" Strata of Soil and/or Rock Sample Topsoil 1 6" 0-110" 3-3 1' 1 1A 7" 1'0"-2'0" 3-4 Rust Brown,loamy,Fine Sand&Silt(SUBSOIL) 2 12" 2'0"-4'0" 4-5-5-6 Rust Brown,Fine Sand&Silt,roots(SUBSOIL) 4' 5 3 8" 5'0"-6'2" 9-17-60/2" Brown, mottled, fine to medium Sand & Silt, little gravel, cobbles 10 4 16" 10'0"-12'0" 13-20-20-24 Same,wet(TILL) 15' Grey,weathered,fractured rock 15 5 2" 15'0"-15'2" 75/2" 17'6" _ Refusal at 17'6" 20 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff. 15-30 V.Stiff, 30+Hard. And 35%to 50% HAMMER FALL IN 30' T 'T BO__ O = S ST Soil Exploration Corp. G Volpe Center Expansion eotechnical Drilling BORING B-7 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4,2011 Ground Elevation: 243 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 27,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 27,2011 10/27/1 5 ft n/a Upon Completion Driller: GG Soil En ineer/Geolo ist: KM Depth Casing Sample Visual Identification Ft. bVtl No. Pen/Rec Depth Blows/6" Strata of Soil and/or Rock Sample 1 1 16" 0"-2'0" 3-4-5-5 Topsoil/Subsoil (TOPSOIL/SUBSOIL) 2 3" 2'0"-3'0" 4-4 Dark Brown,loamy,silty Sand,trace organics 2A 5" 3'0"40" 4-6 3' 5 3 17" 5'0"-7'0" 6-7-9-11 Grey-Brown,mottled,Fine Sand&Silt,trace gravel,wet (GLACIO-FUVIAL) 10 4 0" 10'0"-12'0" 15-20-20-21 10' No recovery 15 5 14" 15'0"-17'0" 19-23-30-30 Grey-Brown,fine to medium Sand&Silt, little gravel,cobbles, wet(TILL) 18'6" Refusal at 18'6" 20 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesioniess: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff, 30+Hard. And 35%to 50% HAMMER FALL IN 30" TEST BORING ® = SHEET 8 Soil Exploration Corp. Volpe Center Expansion Geotechnical Drilling BORING B-8 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive Leominster,MA 01453 North Andover,MA PROJECT N0. 11-1033 978 840-0391 DATE: November 4,2011 Ground Elevation: 243 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 28,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 28,2011 10/28/1 5 ft in/a Upon Completion Driller: GG Soil Engineer Geolo ist: KM Depth Casing Sample Visual Identification Ft. bllft No, Pen/Rec Depth Blows/6" Strata of Soil and/or Rock Sample Topsoil 1 17" 0"-2'0" 3-4-4-4 1' 1 2 3" 2'0"-4'0" 4-4-4-6 Dark Brown, loamy, silty Sand, little gravel, trace organic (FILL) 5 3 17" 5'0"-7'0" 7-11-10-10 Grey-Brown,mottled,Fine Sand&Silt,trace gravel,wet (GLACIO-FLUVIAL) 10 4 18" 10'0"-12'0" 10-10-10-10 Brown,fine to medium Sand&Silt,trace gravel,wet 14' 15 5 18" 15'0"-17'0" 20-20-25-25 Brown,fine to medium Sand&Silt,little gravel,cobbles,wet (TILL) 20 6 3" 20'0"-20'3" 60/3" Weathered Rock 20'3" Refusal at 20'3" 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff. 30+Hard. And 35%to 50% HAMMER FALL IN 30" Soil Exploration Corp. Volpe Center Expansion Geotechnieal Drilling BORING B-9 Groundwater Monitor Well Site: Merrimack College 148 Pioneer Drive PROJECT NO. 11-1033 Leominster,MA 01453 North Andover,MA 978 840-0391 DATE: November 4,2011 Ground Elevation: 243 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 28,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 28,2011 10/28/1 2 ft n/a Upon Completion Driller: GG Soil En ineer/Geologist: KM Depth Casing Sample Visual Identification Ft. evn No. Pen/Rec Depth Blows/6" Strata of Soil and/or Rock Sample Topsoil,wet 1 1 16" 0"-2'0" 3-5-5-4 2 6" 2'0"-3'0" 2-2 3' Grey-Brown,fine to medium Sand, some silt,little gravel,trace 2A 8" 3'0"-4'0" 5-7 organics,wet(FILL) 5 3 12" 5'0"-7'0" 7-10-11-11 5' Grey,Fine Sand&Silt,trace gravel,wet 4 14" 7'0"-9'0" 27-30-17-22 Brown,mottled,Fine Sand&Silt,little gravel(TILL) 10 5 4" 10'0"-10'4" 60/4" 10' Weathered,fractured Rock 11' Refusal at 11 ft 15 20 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff, 15-30 V.Stiff. 30+Hard. And 35%to 50% HAMMER FALL IN 30" TEST B0 EET to Soil Exploration Corp. G Volpe Center Expansion eotechnical Drilling BORING B-10 Groundwater Monitor Well Site: Merrimack College 148 Drive Pioneer Leominster,Pioneer ve North Andover,MA PROJECT NO. 11-1033 978 840-0391 DATE: November 4, 201 1 Ground Elevation: 243 ft+/- GROUNDWATER OBSERVATIONS Date Started: October 28,2011 DATE DEPTH CASING STABILIZATION Date Finished: October 28,2011 10/28/1 4 ft n/a Upon Completion Driller: GG Soil En ineer/Geolo ist: KM Depth Casing Sample Visual Identification Ft. butt No. Pen/Rec Depth Blows/6" Strata of Soil and/or Rock Sample 1 1 14" 1'0"40 5-7-9-9 Brown,fine to medium Sand&Gravel,little silt(FILL) 3' 2 17" 3'0"-5'0" 6-7-6-7 Grey,mottled,Fine Sand&clayey Silt,trace gravel(FILL) 5' 5 3 14" 5'0"-7'0" 19-20-17-15 Brown-Grey,mottled,Fine Sand&Silt,trace gravel,wet 10 4 16" 10'0"-12'0" 13-15-15-18 Brown,fine to medium Sand,some silt,little gravel,wet 15 5 8" 15'0"-15'10" 27-60/4" Grey,Fine Sand&Silt,little gravel,cobbles,wet(TILL) 17'6" Refusal at 17'6" 20 Bore Hole Permeability Tests @ 4 ft&5 ft 25 30 35 Notes: Hollow Stem Auger Size-4-1/4" Cohesionless: 0-4 V.Loose, 4-10 Loose, Trace 0 to 10% CASING SAMPLE CORE TYPE 10-30 M Dense, 30-50 Dense, 50+V Little 10 to 20% ID SIZE(IN) SS Cohesive: 0-2 V Soft, 2-4 Soft, 4-8 M Some 20 to 35% HAMMER WGT(LB) 140 lb. 8-15 Stiff 15-30 V.Stiff, 30+Hard. And 35%to 50% HAMMER FALL IN 30" suvf�,ecr�wuau f oca.wscaayasrf�tnmiscszu f ra f-f o_f f ozavu-rn Haul unrnen uramaga rve�.awg A9 \\\ f Affil 'tt � I err r=;�•�___ \ 7 ,. 243 244 : : : 1%1 9101 SF OF TRIBUTARY €F2- IMPERVIOUS AREA s t E=245 FFEm 215 38'* ✓ FFE=245,3 a_.. =a(,'0 c ! !� AINS DRAINS/ FE=2 6,86 W w _ - -PROP OSG b 1 6,195 SF OF TRIBUTARY IMPERVIOUS AREA ! f` ___'- --_ 243 " I —------------------ hl'P Vanasse i i r r Rain Garden Areas for Water Quality Figure 1 January 2012 Volpe Athletic Center Expansion N.Andover,MA 0 20 40 Feet VHB Project Name: Volpe Athletic Center Proj.No.: 11625.00 Project Location: North Andover,MA Date: January 2012 Calculated by: JWK Rain Garden 1 (runoff from Area M-1 B-11.313) Total Impervious Area= 0.21 Acres Required: Runoff Depth to Required be Treated(in.) Volume(c.f.) Water Quality Volume 0.5 375 Provided: Cumulative Bioretention Basin Elevation Area(s.f.) Volume(c.f.) 242.25 830 0 242.75 1,160 498 Rain Garden 2 (runoff from Area M-1 B-1 1.3C) Total Impervious Area= 0.14 Acres Required: Runoff Depth to Required be Treated(in.) Volume(c.f.) Water Quality Volume 0.5 258 _ Provided: Cumulative Bioretention Basin Elevation Area(s.f.) Volume(c.f.) 242.25 655 0 242.75 920 394 . January 2012\\MAWALD\Id\11625.00\ssheets\Drainage\Water Quality Volume Analysis Sites — �1 V _ f Map Satellite Hybrid Cowty Essex Terrain USGS Minimum number of levels=1 Lij e 3 Zooitt Box (123) ' Date range=01/01 200G aka 't5 1 -, 1 ,1 a' eta cxhi45t 01/12012 ❑ �ri3cut' } f v � 1X1 11 ti oxford,0 State Forest r { Alem� Andover ( 4� i -i x�k NdtJQPfJ" l in crs I rrr -� t - ti. ye ti3t 1 Cancel Drasvini List Sites HTM KM - ., ( l ^�, _,, }tiS, (19?• C LC'A8'! 193 r\ $Aktf}fCt _ .?olf ' ' Sinie F1?resi Site List:14 sites} MiduleaDxSF _ , .' ' } a #+ i 4 , r ? TOpsfb 423247071031301 ) MA-L6W 91 LYNNFIELQ MA :.. ". Lowell?' ~i 423505070491702 ❑ i'' 1' _ ?+. u F MA-WPW 76 WENHAM MA ! ?_, ( , ��y . f : } h 423609070490901 - - ��' hT > bye 5 s tPf 6 A HCW 208 TeAsbur Y ,j 423641071 10 501 r t `' _ s h - A-A7W 462 ANDOVER, MA - i� - I W i ;3:..i: -! ,I:• 1 t�Yr a . F+� Nei- P , Ctt�lttlsfOrd 423713070481301 , - nq MlddTefOn_ 62) Jet t . MA-EXW 11 - tio)„ .` ,, . , • '> Access Gata � -- -� bi,ndi8iwt7 N f. +•} (114 (=) 1 423749071225101 27)... �' MA-CHW 5$0 9 _ l '?k , - X�L- 'W N._>o. s h 423$45070542501 Ri>seil Mill Pond 1 TOPSFIELG, MA e Re 8( n1 7 gancToVn F4te (fa - st 4239160?0562401 ^) site oret Bate 44814Y f S'423927070530501 MA-IPW 340 �) Sag peerVn4 P(ot 6111 � )hA-TQJ 107 1ille rich g r b4 F' �) r txk8101e -l( rica ; d E /n j t _ 't- r +' aYinRit? at 424012070581101 ➢ MA-B1W 295 SOXFORD, hiA s OF4Yer 41 r i <, _ } ., r•tii Wilmington Rendirip u ( T?nm Firnok dr :s 42432207 5 ,7•` . ', �y c T Pg 0 92401 r-uErED>r MA 168 GEORGETOWN MA 2 mi r F j: �Q� _ r`4�) — t�vrnFor i 2x1 r`'• Re:ervAtinn r _ 0tsl 2 km (4)) - a 1. ��, i .; - (i2a) 'Zay�,aii ( Lynnfield f�Ta oafs @20'11 Go le f �n1 -of(1st Lat/Long: 42,5536390 N, 71.3949970 VW Cursor coordinates: UTM: I9T 303376.3 4714051,3 _ GD.DDGDDGQ _ DD°NIM.hMMM' DD°MM'SS.SS" _ References to non-U.S. Department of the Interior(DOI)products do not constitute an endorsement by the DOI, By viewing the Google Alaps API on this web site the user agrees to these TERMS of Service set forth by Google. USGS Groundwater for USA: Water Levels -- 1 sites Page 1. of 2 USGS Home Contact USGS " Search USGS National Water Information System:Web Interface USGS Vlater Resaurcec� Dafa Cateyury,. -_ GeogrrehiC Area; Groundwater ;_'United States News updated Nov,2011 Groundwater levels for the Nation Search Results-- 1 sites found Search Criteria Agency code =usgs site-no list • 423641071102501 Minimum number of levels=1 Date range=01/01/2000. 01/01/2012 Save file of selected sites to local disk for future upload USGS 423641071102501 MA-A]W 462 ANDOVER, MA Essex County,Massachusetts Latitude 42 136'41", Longitude 71 010'25" NAD27 Output formats Land-surface elevation 110 feet above NGVD29 Table of data The depth of the well is 32.5 feet below land surface, rab-separated data This well is completed in the Sand and gravel aquifers(glaciated regions) (N100GLCIAL) national aquifer. Graoh of data This well is completed in the Stratified Deposits, Undifferentiated Reselect period (112SRFD) local aquifer. Water Water Water level, Water level level; feet Referenced level, ' Date Time feet above vertical � Measuring feet Referenced Tt3 below Status g Date Time feet above vertical Measuring land specific datum Agency below Status vertical land specific datum Agency surface datum surface vertical datum 2000-02 03 16.40 12006-02-24 14.01�� USGS 2000-02-28 1 16.02 2006-03-28 14.65�� USGS 2000-03-28 IF-15.491�� 2006-04-27 11 14.79 F2000--04-25]r 15.08 2006-05-24 12.73 USGS 2000-05-30 0 15.09 2006-06-29 F-12.951 USGS 2000-06-27 F 15.02�� 2006-07-26 13.89��_�� USGS 2000-07-25 0 15.30�� 2006-08-24 F 14.551 USGS 2000-08-22 15.411 �=� 2006-09-26 _]F-14.941 E USGS 2000-09 26 15.72 �� 2006-10-24 [:714,97]= USGS 2000-10 25 15.95�E==1 USGS 12000-11-281 Effg= E= USGS 2000-12 Z9 USGS 2001-01-23 15.77 200Z-02-210 15.10 USGS 2001-02-21 15,75 2007-03-27 14.48 USGS 2001-03-27 0 13.81�� 2007-04-24 13.39��F USGS 2001-04-25 14.24 2007-05-23 13.71 USGS 2001-05-24 14.89�� 2007-06-26 14.45 2001-06-19 O 15.02�� 2007-07 24�� USGS USGS 2001-07 2007�O�g 2g 12:�p 15.45�� 2001-08-28 0� USGS 2001-09-26 16.12 USGS 2007-10-23 12:45 EDT 15.74 USGS 2001-10-23 16.35 USGS 2007-11-28 1200 ES 15.61 USGS 2001-11-28 16.68 USGS 2008-01-30 0842 EST 14.91 USGS 2001-12-28 16.52 L�� USGS 2008-02-25 1058 EST 14.14�L�� USGS 2002-01-30 16,40� USGS 2008-03-24 1215 EDT 13.84� U5GS 2002-02-25 16.40�� USGS 2008-04-23 14.20��_�� USGS 2002-03-27 16.13 USGS 2008 05-20 1436 EDT 14.43 USGS 2002-04-26 15.85 USGS 2008-06-24 1227 EDT 14.98 USGS 2002-05-31 15.41 USGS 2008 07-29 0847 EDT 14,50 =F USGS 2002-06-24 15.55�� USGS 2008-08-25 14:25 EDT 14.91��-l� USGS 2002-07-29 16.13 USGS 2008 09-22 13:44 EDT 14.97 1 USGS 2002-08-28 16.49�� USGS 2008-10-29 08:51 EDT 15.00�� USGS USGS Groundwater for USA: Water Levels -- 1 sites Paae 2 of 2002-11 190 15.740�� USGS 2008 11-24 11:56 EST 15.2�� USGS 2002-12 USGS 2008-12-23 12:58 EST 14.37�� USGS 2003-01-310 USGS 2009 01 21 09;52 EST 1445��-�C� USGS 2003-02 250 15.18��= USGS 2009 02-24 08:48 ES 14.57�� USGS 2003-03-250 14.71��0 USGS E:== USGS 2003-05-271 0 14.62�� USGS 2009-04-27 09:15 EDT 14.18��= USGS 2003-06 E:== E::=0] USGS 2003-07-23 1 E=== USGS 2003-08 210 14.83�� USG5 2009 07-30 12:26 ED 14.30�� USGS 2003-09 220 15.30�� USG5 2009 08-24 09:32 EDT 14.80��_�� USG5 2003-10 14.98��0 USG5 12003-11-241 15.36��0 USG5 2009 10-26 08:30 EDT 15.04[�� USGS 2003-12 = USGS 2009 i1-23 11:33 EST 14.87��0 USG5 2004-01-20 USGS 12009-12-211109:33 ES 14.51�� USGS 2004 02-25� 15.45000 USG5 2010 01-25 12:47 EST 14,90�� USGS 2004-03=300 15.3700 USG5 2010-02-22 10:36 EST 15.03��0 USGS 2004-04 Z9 0 14.09�� USG5 2010 03-26 12:14 ED 12.73�� USG5 2004 05-27 F-1 USGS 2010-04-26 09:38 EDT 13.15 �� USG5 2004-07-29� 14.89�� USG5 2010-06-28 09:28 EDT 14.65� �� USGS ao0o0o�� 2004.-08-230 14.4900 USGS 2010-07-26 12:17 ED 15.18��0� USGS . 2004-09 Z4 14.49�� USG5 2010 08-23 13:07 EDT 15.65�� USG5 2004-10-28 = USGS 2004-11-230 15.05�� USG5 2010-10-26 09:57 EDT 15.72C�� USGS 2004-1 �� USGS 2005-0 E== USGS 2005 03-25 0 14.29�0� USGS 2011-01-24 13:09 EST 15.65��_�= USGS 2005-04 220 13,99�� USGS 2011-02-22 13:37 ES 15.45=�_�0 USGS 2005-05-260 13.99�� USGS 2011-03-28 13:25 EDT 14.110E== USG5 2005-06-22 0 14.00�� USGS 2011-04-25 09:13 ED 14.09�� USGS . 2005-07-210 14.48��0 USG5 2011-05-23 13:11 ED 14.520��0 2005-08-300 15:22 2005-09-22 0 15.40�� USGS 2011-07-27 14:54 EDT 15.24 0r� 00. 2005-10-27 14.29�� USGS 2011 08-31 12:34 EDT 15.08 L�E::=0 USGS 2005-11 Z20 15.41000 LISGS11 2011-09-26 12;39 ED 15.06��0� 2005-12-20 15.38�� USGS 2011 10-24 13:48 EDT 14.56 0��0 2006-01-ZS 0 13.98 O�0 USGS 2011-11-28 12:03 ED 14.49 0��0 2011-12-27 12:50 EDT 14.22�� Explanation Section Code Description atus The reported water-level measurement represents a static level St Measuring Agency] Not determined Measuring Agency USG5 US GEOLOGICAL SURVEY 00.estions about sites/data? Data Thos Feedback on this web site Exolanation of terms Automated retrievals Subscribe for system changes Help News Accessibility Plug-Ins FOIA Privacy Policies and Notices r U.S.Department of the Interior I U.S.Geological Survey �J��,ppV Title:Groundwater for USA:Water Levels URL:http://nwis.waterdata.usgs.gov/nwis/gwievels? gaEn cn Page Contact Information: USGS water Data Support Team Page Last Modified:2012-01-16 16:18:47 EST 0.31 0.31 dadymOl - Transportation Land Development Environmental e s e ■ �magmationl mnova*on energy Creating results for our clients and benefits for our communities ■ Jan uary 19,2012 Mr.John Simons,Chairman North Andover Planning Board 1600 Osgood St. North Andover,MA 01845 Mr.Louis Napoli,Chairman North Andover Conservation Commission 1600 Osgood Street,Suite 2-36 North Andover,MA 01845 Re: Response to Stormwater Peer Review Comments DEP File#:2_"2-_15a1 Volpe Athletic Center Expansion—Merrimack College North Andover,Massachusetts Dear Chairmen,Board Members and Commissioners, College,VHB provides the following information° 10'2012.response to the peer On behalf of Merrimack g provides on January review comment letter prepared by Eggleston eston Environmental comments are listed below,followed by the response in italics. The Eggl Comment: ted and the football field detention basin to 1. It is still not clear whether the work called for in lee Stormwater Master Plan,.including the 2005 modifications,has been satisfactorily completed whether engineer's functioning as designed.The response indicates that a as-built plans and an which this project discharges Certificate of Compliance has not yet been issued,but have Commission indicate certification been submitted,or can the Andover o project?Conservation they are satisfied with that portion of the p e We have not been able to locate documentation accepting ehsiofoo otlid public hearing have tion, They did agree Response: W f requested from Andover Con v Volpe Center Expansion project was consistent (January 11,2012)that the proposed 1 of walnut street post Office Box 9151 Watertown,Massachusetts 02471 9151 617.924.1770 - FAX 17.924. 2 86 www.vhb.corn i i Stormwater Response to Comments Project No.: 11625.00 January 19,2012 Page 2 f with the master plan and the banking system. It should also be noted that Andover Conservation has accepted 5 other projects under the master plan approval(Sophomore Housing,Lot D Parking Lot Extension,Monican Boulevard Relocation,Game Field Renovations and Elm Street Entrance), t As part of the approval of the Volpe Center Expansion project,Merrimack College has committed to I implementing a post-construction metering program to document how the detention ponds are operating and submitting a report on the consistency to the master plan. Comment: i 2. Figure Ain the December 8,2011 Response packet submitted to the Andover Conservation _Commission indicates that there are two wetland areas within the Town of North Andover near the terminus of ttie two drain lines that convey flow from the Volpe Center site to the football field detention basin.It is not clear whether these are jurisdictional wetlands and,if so,why they have not been included in the NOI filing.At least one of the drains is being replaced with a larger capacity pipe and outlet protection device in close proximity to the F wetlands. Response: Work associated with the proposed up-sizing of the storm drain line leading to FES-1 will intrude into the 25 ft.no-disturb buffer of the wetlands associated with the Football Field Detention - Basin. This work consists of replacing the existing pipe in place and enhancing the outlet protection at the flared end section(FES). The proposed design would pull the extents of the pipe and apron 5' I finrther away from the wetland than the existing conditions. Additional relief is not possible due to the f proximity of an existing brick sidewalk. The area around the pipe will be restored to its existing lawn condition. The design of the proposed outlet is documented in the attached Figure B—Proposed Outlet Modification to Football Field Detention Pond. The second,northerly outlet shown on the referenced figure is an existing condition that will not be ! modf�ed as part of the proposed project. The proponent respectfidly requests that a waiver be granted for work within the 25'buffer, \\MAWALD\ld\11625.00\dots\letters\2012-01-11 HE Response to Volpe Center Comments 93.doc Stormwater Response to Comments Project No.: 11625.00 January 19,2012 Page 3 Comment: 3. Figure A(referenced above) also calls for a portion of the drain from existing catchbasin B3 to be replaced/upsized and a new riprap apron installed,however I do not believe that was previously discussed as part of this project. Response: The proposed drain re-routing from existing Catch Basin 3(EX-CB3)has been included as part of the Cullen Avenue drainage improvements. This inlet is.collecting runoff from mostly existing impervious area fi oin Cullen Avenue and diverts it to the proposed water quality unit,WQU-A1 (Stormceptor STC-900). Comment: 4. .Maintena2vlce-of-the grass and gravel filter strip upgradient of:Rain Garden 2 should be- - included in the O&M Plan.I would suggest using a larger stone in the trench to keep it in place,as it is likely that snow from the parking lot will be plowed across it.If that is the case, the grass filter strip will also need to be periodically raked to prevent accumulated solids from entering the rain garden. Response: The College provides for snow storage in Austin Field which is adjacent to Rock Ridge Road. Although no snow storage shall take place in the vicinity of the rain garden and grass/stone filter strip,it is agreed that plowing activities will still likely impact the filter strip. The O&M Plan has been updated accordingly to address inspection and maintenance measures associated with the grass and gravel filter strip. Per the MA Stormwater Handbook's reference to the North Carolina Stormwater Manual for grass/gravel combination pretreatment for rain gardens,No. 57 washed stone shall be used in the trench. Comment: 5. The composition of the bioretention soil mix for the rain gardens should be specified on the design details. Response: The bioretention soil mix shall be Agresoil Compost and Agresoil Bioretention Soil as distributed by Agresource,or approved equal,per Specification Section 329500, The Rain Garden detail has been revised to specify the bioretention soil mix. \\ivtAWALD\Id\11625.00\does\letters\2012-01-11 EE Response to Volpe Center Comments#3.doc Stormwater Response to Comments Project No.: 11625.00 January 19,2012 Page 4 j j I I I Merrimack College is appreciative of the additional input provided on the project and we look forward to the opportunity to present these updates at the January 17th Planning " Board meeting Conservation Commission meeting and the January 25th Conservation Commission meeting. t Very truly yours, VANNASE HANGEN BRUSTLIN,Inc 6�eniior stopher M.L t, E,LEED AP i Project ages Cc: Lisa Eggleston-Eggleston Environmental E Jeff Doggett-Merrimack College-Chief of Staff Robert Coppola-Merrimack College-Director of Facilities Attachments: • Revised Rain Garden Detail • Revised Long Term BMP Maintenance Checklist Figure A-Overall Drainage Plan Figure B-Proposed Outlet Modification to Football Field Detention Pond f i I I I C i \\NIAWALD\ld\11625.00\dots\letters\2012-01-11 EE Response to Volpe Center Comments k3.doc PRETREATMENT FILTER STRIP MINIMUM 3' WIDE SOD ,BORDER PER LANDSCAPE PLAN #57 WASHED STONE: 12" WIDE DOUBLE SHREDDED BY 24" DEEP HARDWOOD MULCH SOD,. WIDTH VARIES PLANTS PER 3—FT. MIN. LANDSCAPE PLAN WATER FLOW PONDING S/ 5' <,1_ _ 0 _ a VEL LE D P 1 \�/\�:\\//\\//\\//\\�j\\//\\/\\\ j 9 MAX. 1., ,' B I ORETEN TI ON,, 30„ S01 L M I XTU RE% MIN. �E STI N G /'UNCOMPACTED SOIL/\\//\j�\Y';', // \\ /i/ Notes: 1. SURFACE SIDE SLOPES SHALL BE 3: 1 MAX. 2% MIN. 2. BIORETENTION SOIL MIXTURE SHALL BE AGRESOIL COMPOST AND AGRESOIL BIORETENTION SOIL, AS DISTRIBUTED BY AGRESOURCE, OR APPROVED EQUAL. Rain Garden 6/08 N.T.S. Source: VHB LD_351 Volpe Athletic Center Expansion, North Andover, Massachusetts Long Term Best Management Practices — Maintenance/ Evaluation Checklist Best Date Cleaning/Repair Needed Date of Management Inspection Frequency Inspector Minimum Maintenance and Key Items to Check Performed by Practice ]yes ❑no (List Items) Cleaning/Repair Inspected Outfall Structures Monthly for the first 3 months after • Remove debris and excess vegetation, replace any dislodged riprap ❑yes ❑no construction, annually thereafter. In accordance with • Remove sediment from sediment storage facility (per manufacturer's ❑yes ❑no manufacturer's recommendations guidelines) Water Quality Devices but no less than twice a year . Remove oil and floatables in the oil/inspection port(per manufacturer's following installation and no less guidelines) than once a year thereafter. Ryes ❑no Twice during the first year and . Remove sediment, trash, and debris; once per year thereafter. . Inspect soil and repair eroded areas; Rain Gardens/ • Re-mulch void areas as needed and replace every two years, in the early Bioretention Areas spring; . Remove and replace dead vegetation twice per year, in the spring and fall; • Prune vegetation annually as needed depending on the species. Four times per year • Clean accumulated sand and sediment whenever the depth of deposits is ❑yes ❑no Deep Sump and greater than or equal to one half the depth from the bottom of the invert Hooded Catch basins of the lowest pipe in the basin; • Floatables Every six months for the first year • Inspect filter strip for sediment buildup and the vegetation for signs of ❑yes ❑no and annually thereafter erosion, bare spots, and overall health Gravel/Sod Filter Strip • Regularly rake and mow the grass • Remove sediment from the toe of slope and reseed bare spots, as needed. Stormwater Control Manager �5;� ..,i� I / 1 r c p Gx LIU, r ave r �7 fi:m r r 11'',, i f �Ir�m. ��W✓) 4 y �p�y pp�� 1 4m/Lb • 4 (7~ Z ral g}? yr ! pp pp � mmn« «rise W C) IL W f.l PaF Y < CI C7/5)�} / as ray,ts a u<tt ° a �{ u C ar m +� ®. 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C) Z j, t`tb A. f j LL a 1� Lo ii r A Enright, Jean From: Lisa Eggleston [lisa@egglestonenvironmental.com] Sent: Wednesday, January 25, 2012 2:21 PM To: Hughes, Jennifer Cc: Tymon, Judy Subject: Volpe Center Hi Jennifer, Just want to let you know that I have reviewed the January 19, 2012 response packet from VHB on the Merrimack College Volpe Center project, per your request. With the exception of the final approval of the football field detention basin as-built conditions, which appears to be pending from the Andover Conservation Commission, the submission satisfactorily addresses my review comments. I have no additional comments on the project at this time. I do remind you that an illicit discharge statement based on thorough investigation of the facility by the plumbing engineer is still needed, and the as-built certification prepared by a PE at the completion of project will need to include confirmation of the roof drainage areas in accordance with the approved plans; these can be included in your Order of Conditions. Let me know if you have any questions or need any additional information. Lisa D. Eggleston, P.E. Eggle.ston Environniental Ple,,:i�;e 110t6? OUT'17ew 177,3#11�g a(/cMes,�5., 32 Old Framingham Rd., Unit #29 Sudbury, MA 01776 tei 508.259.1.137 fax 866,,820.7 840 Rsa leston nViij �e ��eonmental.com Please note the Massachusetts Secretary of State's office has determined that most ernails to and from RILINCipal offices and officials are public records.For more information please refer to:tftp-,//vvwW.see.state.nia,us/Drg/preidx.htryi. Please consider the environment before printing this email. ° MASSACHUSETTS RHODE lsl_Mb VIRGINIA 100 Fifth Avenue,5th Floor 401 Wampanoag Trail,Suite 400 4410 E.Claiborne Square,Suite 334 A ' Waltham,Massachusetts 02451 East Providence,Rhode Island 02915 Hampton,Virginia 23666 gr o u p p 781.419.7696 p 401.434.5560 p 757.251.3790 December 15,2011 Mr. Robert Douglas Director of Conservation Community Development& Planning Town Office Building 36 Bartlet Street Andover, Massachusetts 01810 Re: Peer Review of the Stormwater Design for the Expansion of the Volpe Center at Merrimack College ESS Project No. A558-000 Dear Mr. Douglas and Commission Members: ESS Group, Inc. (ESS) is pleased to provide the Andover Conservation Commission with our final review of the Stormwater Report prepared for the Merrimack College Volpe Center Expansion as part of their Request for an Amended Order of Conditions.The report was prepared by Vanasse Hangen Brustlin, Inc. (VHB) to demonstrate compliance with the Massachusetts Department of Environmental Protection (MassDEP) Stormwater Management Standards. The proposed project consists of a 76,000 square foot expansion of the Volpe Athletic Center located, in the northeastern portion of the Merrimack College Campus. In 2001 Merrimack College obtained an Order of Conditions (DEP #90-0750) from the Andover Conservation Commission which included a Master Plan build out through 2020. The 2001 stormwater management system_included two large extended detention basins which were constructed and a peak - flow credit system was initiated. In 2001 the initial flow allowance banked was 62 cubic feet per second (cfs). ESS understands that since 2001 five projects were completed on the campus and the remaining peak flow credit is 50.33 cfs. This proposal estimates utilizing 1.6 cfs of the available peak flow credit leaving 48.7 cfs available for future development at the college. To verify the design is within the parameters of the 2001 Order of Conditions, ESS has reviewed the following documents: • Revised Stormwater Report Materials for Merrimack College Volpe Center Expansion, dated December 2011, prepared by VHB. • Response letter, addressed to the Andover_ Conservation Commission, dated December 8, 2011, prepared by VHB. Site Plans for the Volpe Athletic Center Expansion, Sheets C-3, C=4, C-6 and L-1, dated December 8, 2011, prepared by VHB. Conclusions After reviewing the plans and calculations, ESS believes that the applicant has adequately addressed ESS comments that have been generated during the review process. It is ESS' opinion that the project is designed in compliance with the MassDEP Stormwater Handbook, the Town. of Andover Stormwater Management Regulations and in accordance with the Merrimack College Master Plan 2001 Order of Conditions. 2011 ESS Group,Inc. Awellserver\jobs\a558-000 merrimack college\correspondence\review letter 121511.doc www.essgroup.com environmental consulting &engineering services group - Andover Conservation Commission December 15,2011 In addition the Andover Conservation Commission may choose to request the applicant submit for the record prior to construction; the plumbing plans with the roof drains highlighted, as well as the Stormwater Pollution Prevention Plan (SWPPP) in accordance with EPA's National Pollutant Discharge Elimination System (NP DES) Construction General Permit to be issued in February 2012. Furthermore, the applicant is advised that provision of these comments does not relieve him/her of the responsibility to comply with all Town of Andover Codes and By-Laws, Commonwealth of Massachusetts and Federal Regulations as applicable to this project. Please do not hesitate to contact Janet Carter Bernardo at 781-419-7751 with any questions or concerns. Sincerely, ESS GROUP, INC. 5 � Hanet er Bernar do, PE il Engineer Page 2 ©2011 ESS Group,Ina t\wellsetveAjobs\a558-000 merrimack collegelcorrespondence\review letter 121511.doc www.essgroup.com