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Home My WebLink About03/10/2025 - Response to 1st Peer Review - - 430 OSGOOD STREET r E R A B T WIT-TEN GROUP'' " �" PEER-REVIEW WATER "ESN"NSE 'TO R ... C ,TIs The following are G 1e''s .responses to recommen io s '� *n the rev* � � men letter prepared by the Horsley mitten Group (HW') dated February 20, 2025. A copy of this review letter has been included in this submittal, n r Enclosure . .1. , Confirm where the,existing catch basins in the area of the baseballs field r lln Res nn -, Per record plans nd field observations,, the existIng drainage infrastructure east of the-baseball fiefarea), In and adjacent to Wayne Street drain Into the bordering vegetated wetlands in the general vicinity the 5-series wetland flags via two 2 twe. -four inch 211 corrugated metal)outfalls.1 Confirm what the "'apparent r anh le and "apparent where they discharge Response: the "apparent"'signifier was added to these callouts, as site observations by Gale appeared to disagree with the preparedsurvey p1la,ris., 'These structures are therefore lableled In accoriclancle with Gale's s+ ry n , These structures is charge to V south a site, In the general vicinity f the 5-series,wetlanidflags via two 2 twang- ' w r inch " corrugated metal outfalls. M aA.3. Clarify,the grading and purpose he, proposed - nch stone sty le along the north side of thebaseball fielid. i..Worth Andover Planning Board Response to Review Comment LE Application for Limited Site Plan Review-NA,HS,Athletic Field Improvements, gig March ,2025, Fags Response Per record plino f the original baseball field construction, an infiltration trench exists at they toe of the slope t 'the north. Field observations appear to suggest that this trench was 'Installed in accordance with design, documents. This infiltration trench will remain, with the top "' of cover being removed, then built up to proposed gads with r in rile, l'oam, and seed. Nan Sheet C201 and C5,03 have been revised to reflect s; refer to Enclosure, . b. Other than the stone, base and, subsurface r i wage system proposed at the synthetic turf field, document other 1+ w-impact development 'LiD) options considered for the Project Area. Response: Efforts were made to, within prev:iously disturbedareas, particularly at the shiotput and, tennis areas, where the 'impacts to the overall footprints rints f the facilities is negligible. Other LID opportunitiesproposed for this project area include the reconstruction f the existing infiltration trench as described above, inclusion of an open stone trench east ofthe tennis courts, and the removal and replacement of the existing culvert east f the tennis courts with an open channel and associated wetland, restoration elff rts. 2 . Revise stormwater modeling to use rainfall precipitation depthsprovided Atlas 14, which are 3.16 inches, 5.00 inches and 7.93, inches,for the 2-, 1 -, and yea r storms., respectively. Response: HydroCAD Report, and Stormwater Report have been revised to use the greater, f the rainfall values yet even NOAA andCC- refer to Enclosuresand 1, 2d. Clarify rectangle and call out for" rox. Location,of Subsurface Detention sin". Response:The rectangle represents the,approximiatle horizontal limits of an existin recast subsurface eteunti n ' ,ire that, in Gale's understanding, was 'Installed as part f the rural high school construction., This structure appears to be part of the stormwater management for the site, and receives runoff from thie, highschool parking lots., Per site observations and discussions with the Town and NAH,S,, thi's structure appears t installed in accordance with ,clesign piano and functioning s intended. 2 Revise i r C report and wl�i ti n n rr ti e t u�utili e the, 2-� -, n - ear storms. Response: The Hydr CADReport and Storm1water Report have been revised to utilize the 2,- -, and -year st rms. Refer to Enclosures 2 aru I. San Provide results ofriuu completed. Response:, Refer to Enclosure 5 for the final geotechnilcal evaluation report. North Andover Planning � r Response to Review Comments Application for Limited Site Plan Review-NA,HS,Athletic Field Improvements March 10,2025, Page, fib. Clarify l ue, used for st r , ,e volume providedin section 6.3 of the St+ rm water Report Response: The value for storage volume providied in Section 6.3 has been revised in accordance wlith the peer review comments,; reefer,to Enclosure 2. 3 . Add elevations to the turf field cross section, including the estimated elevation of the perched water table. Confirm that lover-e v do n below the water table will be performed for installation of the synthetic turf field perimeter piping. Response: Detail 1 on PlanSleet C,503 has been revised per this Comme t; refer toe Enclosure 1,, 3d. Clarify hew estimated seasonal high groundwater ES 'IG . was, determined, and confirm that the bottom of the turf iel ' 'base stoneis 2 feet above "it. Respionse: Per Table, 1, Note 2, of the + to n"Ic l report, "'The depth of ES,HWT wasonly observed In the rn tr tla in test pit T I-S. It should be, noted that tIhe ES� observation may unreliable due t l r hied groundwater conditions.," ,ES T was not encountered In test pits T "-1 through h T 4, despite exploration depths averaging a it Feet ' . The report also notes, "As test pits were advanced, it was noted that the glacial till was not saturated and very dense, corresponding 'that the waiter, above was perched and not the, groundwater table."" Furthermore,, the report notes that, based on preliminary observations the, bore , groundwater: was, observed at approximate, depths of five to, eight feet 5'- ') below grade. As,the proposed nt etict rf field gradewill be either at or above the existing natural grass field grade,de, separation from ESHWT to the bottom of the turf base stone is anticipated to be greater than three feet 3' S 3,el. Clarify how stormwiater infiltrating through u.u,g the proposed artificial turf' field will behave over the dense layer of glacial tll'l that is present throughout the site,. Response: Gale does not anticipate wager sheet, flowingalong the t the glacial till buyer. Rainfall that fall's on the syntheticturf surface,will drain vertically'Into the field base stone n be contained viathe concrete perimeter curb, and outlet control structure., The tour field will Duct s a t ntion rmb r, allowing the waiter t rt rnit t infiltrate, Upon infiltration into the existing subgrade bellow the proplos,ed base stonle, approximately three feet T above the observed dense glacial till layer, dale anticipates, groundwater behavior will not deviate to a discernible degree relative to existing conditions., R, Per MSH andhl report, a factor of's,afety of 2 should he applied for field derived infiltration r lu.u+e , and as such a value of 0.2315, inches/hour should be used in HydroCAD model and drawdown calculations. Response: Hydro,CAD model and drawdown calculations, have been revised to utilize, factor of safety ' 2 (0.2,3 in/hr for, the field derived', infiltration value-, refer t Enclosures 2 and 31. NorthAnclover Planning Board Response to Review Carnments A LL E Application for Limited'Site Plan Review-NAHS Athletic Field Improvements dda 4Gw. IMarch 10,1 2025 Page 8, 4b. Parts of Wayne St (accuse road) are within the catchment area, of the project, and it is unclear how this runoff'is, in managed and,whether there is an opportunity to treat the runoff prior to discharging into the,wetland. Response: Run ff from the areas of' Wayne Street described currently draiins into existing stormwater infrastructure and olutfaIls into the BVW in the general vicinity of the 5-series, wetland flags, as it Is a relative low spot for the NAHS campus,. It is, Gale's understanding that regular operation and maintenance of this stormwater infrastructure has been and will continue to be performed by theschool. This area is, also generally within the either the 50 ft. Nb-Build-Zone or the 25 ft. No-Disturb-Zone olf'the bordering vegetated wet'lands,. 4c. Address phosphorus, removal calculations in accordance, with §250-23 C. (1) of the North Andover Stormwater Regulations. Response: Per, the North Andover Stormwater Regulations, redevelopment sites shall be designed to meet a poll,lutant,removal equivalent to 50%,of the average annual load of total phosphorous (TP) related to the total post-construction 'impervious surface, on the site,. Phosphorous loading is anticipated to be low on the site, as,the area gill not be subject to regullar rehicular loading and the proposed synthetic turf playing surface will not require fertilizatilon., Per the, HydroCAD report, the post construction condition has, 1,53 ac' or 616,,650 SF of Impervious area., The regulations note that one method of achieving this removal 'is retaining,a volume of runoff equivalent to or greater than 01.8*Inches multiplied by the total post co'nstruction implervilous area. 0.8 inches, 1,ft 66$,65,0 ft 2 f t3 1 1*,12 1"itches 1 4,443 'The, base stone beneath the synthetic turf fief has a total area of 134,,5,96 SF, and the perimeter curb and outlet, control structure retain stiorm�water up to a certain elevation, allowing stormwater the,opplortunity to infiltrate. square footage of hasht*(elevation of riser—elevation of bottont of hasin)=retention,volunte 134,596 f t2*(103.195,f t—103.85,ft)=13,459 ft3 'The Stormwater report has, been revilsed to include, the above Information# refer to Enclo cur e,2., 9b. Include a sketch with call outs for the various stormwateir practices that require long term,, inspections,and maintenance,. Response: The O&M Plan has, been revised to, include a sketch of stormwater practices, requiring long term linspec tin s and maintenance; refer to,Enclosure 4. Sic. Specify party or parties responsible for the routine inspections and ma'intenance of North h Andover Planning Board Response to Review Comments, L,E oGA,1_ Application for L,imit�ed Site Plea Review S Athletic Field Improvements Page the BIVIRs. Response:,, The, party responsible for inspections,, maintenance,, and the, BMPs shall be the Owner, North rr rer Public Schools. 9 M Include tin t operations and maintenance budget within the & plea Response*, The O&M plan has been reprised to include timat w i t foir BMP management;ent refer to Enclosure 14. W. Per Conservation Agent, specify what maintenance activities, exactly, are included as 01 r vent ati e maintenance"for the tur i ld as rioted on page 2 of the & afar. Response: Preventative maintenance the turf field includes regular, r min ofthe,field lth specialized ui me t to redistribute, the infill material within the field limits and I/ t a -up" the turf fibers. The frequencygrooming in depends, on the level of play, but most,, manufacturers typically recommend every two to rr 2 weeks. ter, rye u�l r maintenance items are,limited to ge,nera] debris clean-up and visual *Inspection,of seams. . Per Conservation, Agent, specify whether maintenance of manholes and cleanouts for the synthetic turf field e ' use with a vacuumtrack or another method. Response: ` , this ru aint nan is performed by vacuum truck. The structures,tures,within the limits, of the turf field, with the ce ti a th ut'l t control structure,, pure smaller PVC structures res rather than,full size precast concrete structures typically seen within roadways, North Andover Plannin,g Board Response to Review Comments ALL,E iG App,lication for Limited Site Plan Review-Nab Athletic Field Improvements March 1,01,,2025 Page 110 We hope you find our responses to the above comments satisfactory. Please, do not hesitate to contact the undersigned, at ('781) 335-6465 or Urftainc.corn, if you have any comments, questions,or require additional information. Best Rega,rds GALE ASSOCIATES., INC. XYI&F. '/R(MCt4VC414],'V' 'Rya/kv D. 7Twzke4-,*ay1"1h1 Kyle F. Rowan Ryan D,Thackeray Project Engineer Sr. Staff Designer KFR/RDT/cmh Enclosures: 1. Revis,led Permit Plan Set 2,. Revised Stormwater Report �Body 3. Revised Hy�d'roCAD Reports 4. Revised Operation and Maintenance Manual 5. Geotechnical Evaluation Report 6. Copy of Hiorsley'Witten Group Review 7. North Andover High School Athletic's Letter of Intent G:\719560\02 Design\perrnit repo rts\p1a n ning\Response to Is,t NA Rieview,\719560 NA Planning, Roard Response Memo 2.0,25, 031.0.docx