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Home My WebLink About0_Prescott Street_North Andover_MA_Response to 2nd HW Comments - Civil Design Gr - Consultant Review - 0 Prescott Street 4/1/2026 4High Street, Suite 155 North Andover, MA 01845 C IVIL D ESIGN G ROUP, LLC Tel 978.794.5400 ENGINEERING. LAND USE. PLANNING. PERMITTING. www.cdgengineering.com April 1, 2026 via email Ms. Jean Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, MA 01845 Re:Proposed Residential Development –Comprehensive Permit Application 0 Prescott Street, North Andover, MA 01845 nd 2Peer Review-Response to comments Dear Ms. Enright and Board Members: On behalf of the applicant,East Mill Housing, LLC, Civil Design Group, LLC (CDG) is in receipt ofthe Horsley Witten Group(HW)second peer reviewcomment letter, dated03/03/2026.Our responsesto the remaining technical commentsare provided in boldbelow the originaland secondarycomments. Supporting plans, calculations and additional informationare enclosed herein: 2.j.In accordance with §250-23 E. (22), HW recommends that the Applicant provides pipe sizing calculations using Mannings Equation and confirms that the drainage pipes can accommodate a 25-year storm event. CDG Response: The Applicant has requested a waiver from the local Stormwater Bylaw. The plan intends to comply with the applicable stormwater regulations in accordance with the MassDEP Stormwater Handbook and the EPA NPDES/SWPPP requirements.The drainage connection points in High Street are 12” pipe, therefore, increasing pipe sizes based on onsite pipe capacity would be ineffective if its required. The Applicant intends to continue their conversation with the DPW regarding the regional flood management study and to explore alternatives to maximize runoff conveyance through the campus. HW March3,2026:TheApplicant hasrequested awaiverfromthelocalStormwater Bylaw.TheApplicanthas statedthatthedrainage connectionin HighStreet consistsof 12-inch pipes andincreasingthe pipe sizes basedon onsitepipecapacitywould be ineffective.TheApplicanthas statedthatitwill continueits conversationwiththe Department of PublicWorks(DPW)regarding theregional floodmanagementstudy andto explorealternativestomaximizerunoff conveyance throughthe campus. HW recommends thatthe ZBA request updateson the conversations between the Applicant and the DPW. CDG Response: The project proposes an alternative drainage plan that includes a drainage connection from the project to the 36” drain line traversing through the AVB WestMill property. The connection is made via a proposed 18” drain line 1 4High Street, Suite 155 North Andover, MA 01845 C IVIL D ESIGN G ROUP, LLC Tel 978.794.5400 ENGINEERING. LAND USE. PLANNING. PERMITTING. www.cdgengineering.com across the Prescott intersection and would take the new building rooftop and the internal courtyards. Please note the following: ·The 36” pipe was originally installed to convey offsite upstream runoff from the Prescott Street neighborhood through the Avalon West Mill property. ·Based on discussions with DPW, portions of the Prescott neighborhood drainage system has been re-routed over the years to discharge onto the RCG East Mill property, therefore, it is difficult to delineate an accurate watershed. ·Proposed DMH-6 acts like a diversion manhole whereby the 18” pipe would need to reach max capacity before flow would be diverted to the 12” pipe. ·The project proposes a newcatch basin at the Prescott/High Street intersection to capture surface runoff as it was intended to redirect runoff away from High Street. ·The 36” pipe also has a 12” bypass whereby the larger pipe would need to reach full flow before the 12” bypass is activated. (see DMH-3D). Therefore, multipleconveyance optionswould exist for surface runoff to reach its destination points west of the campus toreduce the likelihood of a bottleneckat the High Street low point. Our office has coordinated with DPW and they appear to concur with our design approach. 2.k.HW notesthattheexistingpipeconfigurationattheintersectionwithHighStreetand thedriveway accessdriveisconfusing.HWrequeststhattheApplicant clarifyhowthe various catchbasins andmanholesareconnected. Furthermore,theApplicant is connecting anew18-inchdrainpipe totheexistingdrainagesystem atanexistingcatch basin, itis notclearthesizeoftheexistingdrainpipes andiftheexistingsystemcan managetheproposedrunoff. HWrecommendsthattheApplicantprovidesadditional documentationontheexistingdrainpipes.Iffeasible, HWrecommendsthatthe Applicant tieintotheexistingsystematamanhole. CDG Response: The existing drainage infrastructure is comprised of multiplecatch basins that ultimately tie intotheHigh Streetdrainage systemand is conveyed towards the large existing culvert that traverses to Mill Pondbehind the West Mill Development.The proposed 18” pipe denotation is intended to indicate a 12” pipe, and the same has been corrected on the plans. Since the watershed to swale has been reduced by 2 acres, the 18” existing pipe is oversized as compared to the contributing flow. For comparison, a 12” RCP with a 1.2% slope can convey 4.6 cfs of runoff and an 18” RCP with the same slope can convey over 11 cfs. The contributing watershed generates approximately 4.1 cfs of flow. HW March 3, 2026: The Applicant has reduced the proposed 18-inch pipe to a 12-inch pipe. Since the watershed to the swale has been reduced by 2 acres, the existing 18- inch pipe is oversized as compared to the contributing flow. The discharge to the municipal stormwater system should be part of the ongoing discussions with the DPW. CDG Response: Acknowledged. 2 4High Street, Suite 155 North Andover, MA 01845 C IVIL D ESIGN G ROUP, LLC Tel 978.794.5400 ENGINEERING. LAND USE. PLANNING. PERMITTING. www.cdgengineering.com 4.a.TheApplicant hasprovidedwaterqualitycalculations toconfirmthatthetreatment trainsexceedthe80% TSSremovalrequirement pertheMSHand§250-23C.(1) of theNorthAndover StormwaterRegulations. HWrecommends thattheApplicant providesdocumentationconfirmingtheTSSremovalprovidedbytheproposed proprietarydevices. HWnotesthattheApplicant hasprovidedadetailofa Hydroworks HS4.However, wecouldnot locatewherethis deviceis proposed. CDG Response: The HS unit is located in front of the garage portion of the building and is labelled as DMH-9. The rooftop garage parking lot drains into the HS unit. HW March 3, 2026: The Applicant has clarified the location of the water quality unit in front of the garage portion of the building at drain manhole (DMH) 9 and provided documentation confirming the TSS removal provided. HW recommends that a second water quality unit be provided for the closed drainage system on the east side of the parcel, possibly at DMH 2. CDG Response: DMH-2 has been revised to include an HS4 Unit. 9.g.HW recommends that the Applicant includes the snow storage locations on the Figure-1 BMP Location Plan. CDG Response: Snow storage areas have been added to the BMP Plan. HW March 3, 2026: The Applicant has included snow storage locations on Figure-1. HW recommends that the Applicant include the snow storage location for the roof deck of the proposed garage. CDG Response: It is presumed that snow will be removed by hand. Typically, the roof is designed to handle the snow load and melting is expedient since rooftops are not typically blocked by trees, therefore, sun exposure is maximized. Also, the snowfall would be limited to only what falls on the roof as opposed to other areas that are plowed and stored. 15.e. The Applicant hasprovided a PhotometricCalculation Plan, Sheet L3.0.The lightcandles appeartospill over ontotheMeadow View Condominiums and slightly ontotheproperty at 39Prescott.HW recommendsthatthe Applicant confirmthat the amount of spillover will not be anuisance for any abutting residents. CDG Response: The lighting and landscape plan has been updated including placing shields oncertain lights to prevent light trespass. HW March 3, 2026: The Applicant has updated the light and landscape plan to prevent light trespass. There still appears to be some spillover. HW recommends that the Applicant confirm that the amount of spillover will not be a nuisance for any abutting residents. CDG Response:The revised photometric plan has been completed and it has been determined that light‘trespass’can’t be avoided alongthe southerlylot (Avalon abutter) unless a fence is installed. As such, the 3 4High Street, Suite 155 North Andover, MA 01845 C IVIL D ESIGN G ROUP, LLC Tel 978.794.5400 ENGINEERING. LAND USE. PLANNING. PERMITTING. www.cdgengineering.com Applicant would likean opportunity to add alightingwaiver tothe list of waivers. We trust the responses provided above and the enclosed plans and documentation sufficiently address the comments issued by the peer reviewer. Please feel free to contact our office if you have any questions or requirefurther clarification. Sincerely, C IVIL D ESIGN G ROUP, LLC Philip R. Henry, P.E. Principal cc.Mr. David Steinbergh, RCG Mr. John Smolak, Esq. Enclosures 4