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HomeMy WebLinkAboutMiscellaneous - 33 WALKER ROAD 4/30/2018 (4)w 3 a Redgate Pasture Definitive Subdivision The Planning Board herein APPROVES the Definitive Subdivision for a four (4) lot subdivision, made up of four new single family homes known as Redgate Subdivision. Redgate Realty Trust, 33 Walker Road, North Andover, MA 01845 submitted this application on May 14, 2001 in accordance with the Order of Remand issued by the Land Court on October 22, 2001. The area affected is located off Salem Street in the R-2 Zoning District, Map 65, Lot 21 & 164. This approval is for the construction of four lots ONLY. The Planning Board makes the following findings as required by the Rules and Regulations Governing the Subdivision of Land: A. The Definitive Plan, dated November 22, 1996, revised last on 2/26/01 includes all of the information indicated in Section 3 of the Rules and Regulations concerning the procedure for the submission of plans. B. The Definitive Plan adheres to all of the design standards as indicated in Section 7 of the Rules and Regulations. C. The Definitive Plan is in conformance with the purpose and intent of the Subdivision Control Law. D. The Definitive Plan complies with all of the review comments submitted by various town departments in order to comply with state law, town by-laws and insure the public health, safety and welfare of the town. A review by Coler & Colantonio, the town's outside engineering consultant, dated March 20, 2001 indicates that all outstanding engineering issues have been addressed. Also, a review by James Rand, Director of Engineering from the Department of Public Works, indicates that all slopes have been stabilized satisfactorily. (memos attached). Furthermore, a separate cash performance bond, as provided in condition 3c, will be posted to ensure the stabilization of the slopes for a period of three years from the date of completion of slope construction or acceptance of the subdivision roadway by Town Meeting, whichever comes first. E. The Definitive Plan complies with all standards and requirements of the Zoning Bylaw and the Board of Health. Finally, the Planning Board finds that the Definitive Subdivision complies with Town Bylaw requirements so long as the following conditions are complied with: 1 1) Environmental Monitor: The applicant shall designate an independent environmental monitor who shall be chosen in consultant with the Planning Department. The Environmental Monitor must be available upon four (4) hours' notice to inspect the site with the Planning Board designated official. The Environmental Monitor shall make weekly inspections of the project and file monthly reports to the Planning Board throughout the duration of the project. The monthly reports shall detail area of non- compliance, if any and actions taken to resolve these issues. The environmental monitor referred to in condition #1 must provide in-depth reports relative to the stabilization of the slopes located on the rear of Lots 2 and 3. The environmental monitor shall make weekly inspections during the construction of the slopes and file the weekly reports to the Planning Board throughout the duration of the project. The environmental monitor shall schedule monthly inspections with the Town Planner and the Town Engineer of the Department of Public Works during the construction of the slopes until the slopes have been fully constructed. The environmental monitor shall appear before the Planning Board at one point during and upon completion of the construction of the slopes to present their findings as to the slope stabilization. 2) Prior to endorsement of the plans by the Planning Board the applicant shall adhere to the following: a) A Site Opening Bond in the amount of ten thousand ($10,000) dollars to be held by the Town of North Andover. The Site Opening Bond shall be in the form of a check made out to the Town of North Andover that will be placed into an interest bearing escrow account. A covenant (FORM I) securing all lots within the subdivision for the construction of ways and municipal services must be submitted to the Planning Board. Said lots may be released from the covenant upon posting of security as required in Condition 5(c). b) The applicant must submit to the Town Planner a FORM M for all utilities and easements placed on the subdivision. c) All subdivision application fees must be paid in full and verified by the Town Planner. d) The applicant must meet with the Town Planner in order to ensure that the plans conform to the Board's decision. A full set of final plans incorporating a landscaping buffer comprised of trees of an evergreen species along the frontage of Lot 1 on Salem Street to adequately screen the detention pond must be submitted to the Town Planner. Additionally, the plans must be revised to incorporate a detail of erosion control matting for the slopes on Lots 2 and 3; and to include a detail of the detention pond depicting a v -shaped outlet containing adjustable baffles to accommodate the 25, 50 and 100 year storm must be submitted to the Town Planner for review and approval prior to 2 endorsement by the Planning Board, within ninety (90) days of filing the decision with the Town Clerk. e) The Subdivision Decision for this project must appear on the mylars. f) All documents shall be prepared at the expense of the applicant, as required by the Planning Board Rules and Regulations Governing the Subdivision of Land. 3) Prior to ANY WORK on site: a) Yellow "Caution" tape must be placed along the limit of clearing and grading as shown on the plan. The Planning Staff must be contacted prior to any cutting and or clearing on site. b) All erosion control measures as shown on the plan and outlined in the erosion control plan must be in place and reviewed by the Town Planner. c) A Slope Stabilization Bond in the amount of twenty thousand ($20,000) to be held by the Town of North Andover. The Slope Stabilization Bond shall be in the form of a check made out to the Town of North Andover that will be placed into an interest bearing escrow account. These monies may be utilized by the town to ensure the stabilization of the slopes. These monies, or the balance thereof, will not be released until three years from the date of completion of slope construction or acceptance of the subdivision roadway by Town Meeting, whichever comes first. For Purposes of this section, "date of completion of slope construction" shall be defined as complete when the Town Engineer certifies in writing to the Planning Board that the slopes have been constructed in accordance with the approved plans and this decision. Furthermore, the Town Engineer shall not make this determination until a joint site visit has been scheduled with the Planning Board. 4) Throughout and During Construction: a) Dust mitigation and roadway cleaning must be performed weekly, or as deemed necessary by the Town Planner, throughout the construction process. b) Street sweeping must be performed, at least once per month, throughout the construction process, or more frequently as directed by the Town Planner. c) Hours of operation during construction are limited from 7 a.m. to 5 p.m., Monday through Friday and 8 a.m. — 5 p.m. on Saturdays. d) A construction schedule shall be submitted to the Planning Staff for the purpose of tracking the construction and informing the public of anticipated activities on the site. 3 5) Prior to any lots being released from the statutory covenants: a) Three (3) complete copies of the endorsed and recorded subdivision plans and one (1) certified copy of the following documents: recorded subdivision approval, recorded Covenant (FORM 1), recorded Growth Management Development Schedule, and recorded FORM M must be submitted to the Town Planner as proof of recording. b) The applicant must submit a lot release FORM J to the Planning Board for signature. c) A Performance Security in an amount to be determined by the Planning Board, shall be posted to ensure completion of the work in accordance with the Plans approved as part of this conditional approval. The bond must be in the form acceptable to the North Andover Planning Board. Items covered by the Bond may include, but shall not be limited to: i) as -built drawings; ii) sewers and utilities iii) roadway construction and maintenance iv) lot and site erosion control v) site screening and street trees vi)drainage facilities vii)site restoration viii)final site cleanup 6) Prior to the issuance of a building permit for an individual lot, the following information is required by the Planning Department: a) The applicant must submit a certified copy of the recorded FORM J referred to in Condition 5(b) above. b) A plot plan for the lot in question must be submitted, which includes all of the following: i) location of the structure, ii) location of the driveways, iii) location of the septic systems if applicable, iv) location of all water and sewer lines, v) location of wetlands and any site improvements required under a NACC order of condition, vi) any grading called for on the lot, vii) all required zoning setbacks, viii)Location of any drainage, utility and other easements. 11 c) All appropriate erosion control measures for the lot shall be in place. The Planning Board or Staff shall make final determination of appropriate measures. d) Lot numbers, visible from the roadways must be posted on all lots. e) An as -built plan must be submitted to the Division of Public Works for review and approval prior to acceptance of the sewer appurtenances for use. f) The roadway must be constructed to at least binder coat of pavement to properly access the lot in question. Prior to construction of the binder coat, the applicant shall ensure that all required inspection and testing of water, sewer, and drainage facilities has been completed. The applicant must submit to the Town Planner and the Department of Public Works an interim as -built, certified by a professional engineer, verifying that all utilities have been installed in accordance with the plans and profile sheet. g) The applicant is required to pay sewer mitigation fees in accordance with the current and prescribed policies at the Department of Public Works. Proof of payment must be supplied to the Planning Department. h) If a sidewalk is to be constructed in front of the lot, then such sidewalk must be graded and staked at a minimum. 7) Prior to a Certificate of Occupancy being requested for an individual lot, the following shall be required: a) All necessary permits and approvals for the lot in question shall be obtained from the North Andover Board of Health, and Conservation Commission. b) Permanent house numbers must be posted on dwellings and be visible from the road. c) There shall be no driveways placed where stone bound monuments and/or catch basins are to be set. It shall be the developer's responsibility to assure the proper placement of the driveways regardless of whether individual lots are sold. The Planning Board requires any driveway to be moved at the owner's expense if such driveway is at a catch basin or stone bound position. 8) Prior to the final release of security retained for the site by the Town, the following shall be completed by the applicant: a) An as -built plan and profile of the site shall be submitted to the DPW and Planning Department for review and approval. 5 b) An as -built plan and profile of the slopes on Lots 2 and 3 must be submitted to the DPW and Planning Department for review and approval. c) The applicant shall petition Town Meeting for public acceptance of the street. Prior to submitting a warrant for such petition the applicant shall review the subdivision and all remaining work with the Town Planner and Department of Public Works. The Planning Board shall hold a portion of the subdivision bond for continued maintenance and operations until such time as Town Meeting has accepted (or rejected in favor of private ownership) the roadways. It shall be the developer's responsibility to insure that all proper easements have been recorded at the Registry of Deeds. 9) The Applicant shall ensure that all Planning, Conservation Commission, Board of Health and Division of Public Works requirements are satisfied and that construction was in strict compliance with all approved plans and conditions. 10) The applicant shall adhere to the following requirements of the Fire Department: a) Open burning is allowed by permit only after consultation with the Fire Department. b) Underground fuel storage will be allowed in conformance with the Town Bylaws and State Statute and only with the review and approval of the Fire Department and Conservation Commission. 11) There shall be no burying or dumping of construction material on site. 12) The location of any stump dumps on site must be pre -approved by the Planning Board. 13) The contractor shall contact Dig Safe at least 72 hours prior to commencing any excavation. 14) Gas, Telephone, Cable, and Electric utilities shall be installed as specified by the respective utility companies. 15) Any action by a Town Board, Commission, or Department which requires changes in the roadway alignment, placement of any easements or utilities, drainage facilities, grading or no cut lines, may be subject to modification by the Planning Board. 16) The utilities must be installed and the streets or ways constructed to binder coat two years from this approval. If the utilities are not installed, the streets or ways are not constructed to binder coat and the Planning Board has not granted an extension by the above referenced date, this definitive subdivision approval will be deemed to have lapsed. 17) This Definitive Subdivision Plan approval is based upon the following information which is incorporated into this decision by reference: rel Plan titled: RedGate Pasture a Report titled: Drainage Report Prepared by: Daniel Koravos, P.E. 25 Teloian Drive Hudson, NH 03051-3937 Dated: April 4, 1999, revised March 22, 2000 Attachments: March 20, 2001 Engineering Review, Coler & Colantonio Memorandum to Heidi Griffin from Jim Rand dated 6/4/01 7 Definitive Subdivision Plan North Andover, Massachusetts 01845 Dated: November 22, 1996, revised 9/2/97, 12/26/97, 1/19/98, 6/14/99, 2/26/01 Applicant: RedGate Realty Trust 33 Walker Road North Andover, MA 01845 Civil Engineer:New England Engineering Services, Inc. 33 Walker Road, Suite 23 North Andover, MA 01845 Sheets: 1-7 Scale: F=40' a Report titled: Drainage Report Prepared by: Daniel Koravos, P.E. 25 Teloian Drive Hudson, NH 03051-3937 Dated: April 4, 1999, revised March 22, 2000 Attachments: March 20, 2001 Engineering Review, Coler & Colantonio Memorandum to Heidi Griffin from Jim Rand dated 6/4/01 7 U COLANTONIOZ ENGINEERS AND SCIENTISTS March 20, 2001 Heidi Griffin Planning Board 27 Charles Street North Andover, MA 01845 RE: Supplemental Engineering Review Red Gate Pasture Revised Definitive Subdivision Dear Ms. Griffin. In response to your request, Coler & CoIantonio, Inc. has reviewed the supplemental submittal package for the above referenced site. The project has been reviewed for conformance to the requirements of the "Rules and Regulations Governing the Subdivision of Land" in North Andover as well as standard engineering practice. The submittal: package included the following information: Plans Entitled: • "Red Gate Pasture, Definitive Subdivision Plan" seven sheets dated 11/22/96, revised on 2/26/01, Prepared by New England Engineering Services, Inc. Reports Entitled • Response letter dated February 26, 2001 prepared by Benjamin C. Osgood, Jr. Current comments are in italics. Previous comments are screened. Subdivision Requirements: 1. Section 3. C.) 3.) c.) A test pit is shown in the driginal detention pond area- Based upon the information in New England Engineering Services letter, ground water is located 2 to 3 feet below the surface. The new detention ponds are located in cut areas ranging in depth from 8 to 12 feet. This could result in unstable slopes in the detention basins. We anticipate that slope stability will be a concern. The Applicant, may want to consider altematives to patching unstable slopes with iip rap. This is not desired in residential sites. 101 Accord Park Drive 781 982-5400 l Norwell, MA 02061-1685 Fax: 781 982-5490 Test Arts t►l?ieully. ,should be provided iii the )pit iiiit.- of they pi-opo house locations,. and the detention basin on Lot 4.:1 ese teats shoidd be performed by a licensed sail erahtritor ro indicate lii;;h gl citliirlwciter conditioii.s. In precious, .submissions it has been that the seasonal welter table is appro iinatell- 10-incites below grade. No additional testing has been provided. As rioted above estimated high groundwater Is within 10" of the suiface. The. design indiceltes.foundations beloir the high grollndivater elevation. The plans and details indicrae folailrlation drains on each house, which di.sch arae overland. The millinn ni cover over the proposed curtain drains should be indicated. A slope stabilization and maintenance plan including details of stabilization inethods should be provided No Additional testing itiforination has been provided for the sn'ule within lot d. It is our under.standirtg that es•tinta-ted high grounrhvater is within 10" o}'the existing surface. Overall, the site regnires axtensh-e cut. Groutidwater is proposed to be directed to the infiltrationliletention basin via curtain drains, faundarion drains or overland f o from these pipes. The groundiv ater could contribicte eitensive flow to the basin e)'eia during a non-stonil period. Constant flow from these grounehvater .sources into the infiltration basin mai shorten the easeful life of the basin. The n1noff from the .subdrain located on the east side of the slope (int . 170.00) should be directed atiti a from the eastent abutter to be consistent with the hydrology catchment area plaits. Care .should be taken during construction to assure the eastern abutter i:s not inipacted from an increase of storm water onto their property. The inininluin corer over the proposed curtain drain appears to be 30". The slope .stabilization plait includes placing rip-rap in the areas of groundwater breakout, iritli loran and seed covering the rip-resp. The DPIV should review and comment on the slope stabilization method A gravel drain has been added to the bottom of the infiltration basin. The. drain appears to have adequate capacity to dissipate groundwater flow. We recommend the DPW to comment on slope stabilization. ?. Section 3. C.) 3.) d.) See Drainage Issues below. 3_ Section 3. C.) 3.) k.) g.) Satisfactory•, roadway stationing has been added. 4. Section 3. C.) 3.:) k.) h.) Satisfactory, the tot plan has been corrected. 5. Section 3. C.) 3..) k.) j.) Satisfactory, The water main has been relocated and the hydrant has been shown. 6. Section 3. C.) 3.) k.) k.) Satisfactory. the contours have been extended. 7. Section 3, C.) 3.) k.) l.) Satisfactory. the fol=iage line has been added to the drainage plans. 2 N 8. Section 3. C.) 3.) k.) tn.) Previous correspondence recommended that test pits be excavated within the proposers detention basin and at locations of major cuts in slopes to determine the elevation of the eroundwater table. Reportedly, seasonal high water will be as close as .10'- to the surface based on hand testing performed. This could result in long term maintenance difficulty for the town due to groundwater breakout, unstable slopes and difficulty maintaining vegetation. Subdrains should be located upgrade of potential groundwater breakout on the cut slope, generally this is at or gear the top of the slope. Swales to the catch basins should be more defined. There is significant flow to these inlets in large storm events The sirale details rise inconsistent with the plans. Comment remains. Ae Swale detail has been modified to match theplans. 77re Swale pitch is 18% and it is unclear thra it will not erode dice to high flow relociries. The srrade detail has been modified The detail shows a 12" depth of rip -rap, consisting of stone between 6" and 10''' in size. It should be noted that long term aaaaintencuace drfculh- for the Town nagy result due to groundwater break-out, unstable slopes and maintaining vegetation on the slopes.. 9. Section 3. C.) 3.) k.) n.) We recommend that the existing drainage channel, which was observed by us in the field, be indicated on the plans. This channel should also be used in the drainage calculations for the flow path. This channel was located in the slope and not in the field. No fanTher comment. 10 Section 3.C.) 3.)k.)p.) The profile does not comply with all the .requirements of this section. The proposed roadway grade should be indicated and the location of the benchmark should be indicated on the plan. Existing sideline grades have not been shown, elevations have not been labeled at the top and bottom of all even grades. 25' intervals and on vertical curves. The stopping sight distance at the vertical curve station 00+40 to 00+90 is inadequate for a speed of 30 miles per hour. Information is still missing from the profile. Specifically, roadway grade is not indicated, sideline grades have not been shown, elevations at 25 -foot intervals on vertical curves and stopping sight distance is not in conformance with the requirements_ It is assumed that a waiver Nvill be requested from the stopping sight distance requirement. The plans hm•e been amended to include rocadi,•cay grades, side line grades, adegajate vertical curve design and 25 foot elerraions inters°als at r•ertical Curve locations. A sight distance study and reinediution plan has been pertonaaed and si4binatred. Nc) f ofrther ronu tent. 11. Section 3. C.) 4.) Satisfactory 3 12. Section 7.) A. 3.) b..) There is insufficient data on the profile to determi=ne if the leveling area is adequate. Secy 10. Above There appears to be a SD' leveling elrea with cr 21170 slope. This comment is safi,cfactorfl.v addressed. 13. Section 7. D.) It is our understanding the Planning Board will decide whether a sidewalk is required or a donation will be made to the sidewalk fund. No jZ rlher COIMIrent. 14. Section 7. E.) 1.) Satisfactory, the street trees are shovvn on the pians. The PIanning Board may require information on the type of tree to be planted. Trees should be indicated outside of the right of %pati. The proposed. street trees have been relocated outside of the Raw. Nofurther 15. Section 7. G.) 1.) Satisfactory, electric lines shown on the plans. tb. Section 7. L.) 1.) Satisfactory. the proposed fire hydrant is shown. 17. Satisfactory, a north arro«• has been shown on the Locus plan. 18. Erosion control measures are shown on the plans. however, they should be cle-arly labeled and/or shown on the legend. Erosion control measures should 'also be sho%,,,n around catch basins and detention pond outlets. We recommend that a stabilized construction enhance be provided and erosion control be installed along the Salem Street right of way - We recommend that a sates iiawy slope hispection. maintenance and stabilization plata be submitted. A 1abilized cons_'rlrction entrance I= been indicated on the plans - Erosion control h(is beelr provided throe how the thnit of work. No further conunent. 19. The proposed sub -drain locations should be shown on the plans and detailed. The plans seem to indicate erasion control measures only. We understand the symbols on the plans. No further comment. Drainage Issues: 20. Satisfactory, both Pre and Post construction drainage area plans have been submitted. 21. Satisfactory, runoff curve nunil.)ers now include meadow. 11 221. Satisfactory, [tic sheet low lengths used in. the "t -R-55 calculations etre now 100 feet or less. 2:3. The comment on the outlet structure is no longer applicable.The inipact of existing flow and pipe capacity in the Salem Street drainage s;•stem should be considered. It is possible that the Salem Street systent is more restrictive than the proposed outlet structure. This could result in offsite impacts. Outflows .from the proposed outlet structure will enter the municipal drainage system for the 1(1 and 100 -year storms_ The existing municipal system ,shouICI be modeled For these storms. Con nlent remains. The proposed flolr's and volumes to the e..list iig itiunicipcil Stormwcttc'.r s i,stent. are reduced front existin, conditions. The proposed detention/infiltration basin should be excavated to the elevation t)f, the underlying sandy soil and backfilled with similarly pervious nuverial. The functionality of this basin is contingent upon sititahle soils at the bottom of the basin. A Rote has been added to sheet S> Sediment basin and ittfiltrationldetentton pond detail stating all loans, .subsoil, fill or other deleterious material .shall be removed in. the area of the basin bottom and replaced with clean sant. Top area with 4" loamy sand., rak=e stnooth and seed. 7ypir. ally loant_i= sand has a lower permeability than sand. We recommend AV te.sring to demonstrate compliance tvith the design be required A gravel drain has been added to the bottom of the infiltration basin. The drain appears to have adequate capacity to dissipate groundivaterflow. 24. It is unclear if the proposed drainage channel will he located in the Salem Street right- . of -way. The dimensions of the channel, as detailed, are inconsistent with the overflow- ditch described in the drainage report. The overflow ditch does not appear to be included in the drainage model. Capacity calculations should be included in the drainage report to support the proposed design. The plans do not indicate a channel, although a channel detail .is included in the report. Tire rip -rap swales slunild be indicated as such on the plans_ These sivales ,should be modeled for rel ocit}; and capacity. The reported sivale at Salem Street should be. indicated and modeled. The rip -rap swale detail was clarijhed. Repoitedl ti-. there is no swale e_t7sting or proposed at Salem .Streel. The desi,;ti calculation for the level spreader should be submitted. Existing spot grudes in the vicinity of the proposed level spreader should be submitted. Based on the new .spot elevations. the Jloit• front the detention basin appears to, floly into Salem Street within a proposed depression. The proposed elevation at the northeast property corner (Elev. 144.74) is higher than the northwesterly elevation of 143.67. The rim of the existing cutch basin located north-west Elf rh s area is elev. 144.29. Calculations_for the level lip spreadertire inchided with the letter response. 5 a The detail avid plaits show a letzgih (j ftppr(rl'hnateh- -15'. The calculations use 31'. The colculeations do not appear to be c.crosiStent with the plans and details. Additional spot grades have been added to the grading plan and the flow from the basin appears to flow to the double catch basins. Satisfactorily addressed. 25. The regulations require a catch basin to manhole alTangement. The plans indicate the outlet from Pond 17 enters a catch basin. The outlet from this pond should discharge into a'manhol.e. This design should be revised to comply with Town requirements. Satisfactory. No further comment. 26. The ultimate discharge of the closed stormwater system in Salem Street is not described in the report. Calculations should show this system has the capacity for the new flows. The intent of the design is to meet or reduce existing runoff rates. The timing of this runoff to the street system and the additional runoff volume may itirpact the existing system. If the capacity of Salem Street system is .restricted, the increase in total runoff could result in offsite impacts. The Post -development runoff volume entering the Salem Street drainage system will increase for all storms. The Department of Public Works should be aware of this especially if the drainage system is currently undersized. Volume calculations for the infiltration area should be clarified in the report. In addition, we recommend that the infiltration system be further detailed to indicate sections and elevations on the plans. The sample design in the report indicates pipe outlets from each Infiltrator versus the design proposed. It is unclear that the increased volume from development haus been accommodated in the design. The report lists total runoff voluune pre and post, however, it is unclear where the values for post development are in the report. The proposed sub -surface detention Mesio has been redesigned as a surface infiltration basin. It is unclear that the proposed Detention Basila .nit Lot 4 is located above the groundwater table. In addition, the ultirnate discharge paint frons Dere-ration Basila A-1 should be clarified, detailed ctndl modeled. A model.for this basin should be provided and a satisfactory overflow should be desz.gned and indicated. -Tlw bene on this basin shn dd be uvidened to $ feet The grading for the shale area within Lot 4 will result iii the discharge of grotar)divater to the stivale. The discharge point for basin A-1 has been clarified. Please see comment #24 regarding the shot grades. The be)711 iridth has been tividened to 8 - .feet. Spot grades have been provided. however it is unclear; based on the proposed spot grades hois- or where the water will eater the Saler) Street drainage systeinfirom the proposed irufilt)atiorr/dete)ttic'at bczsirr. The tearer appears to puddle between the e�risting catch basin located northeast of the proposed entrance tend the proposed spot elevulion of 144.74. Satisfactorily addressed. Col Additional Comments 27. The proposed roadtv'ay will have a slope of 8 �..It is our understanding this issue was discussed with the Planning Board and the change in grade was recommended. No further comment. 28. The detention pontis do not provide an eniergency spillway. Calculations should include routing of the I00 -year storm with a plugged outlet to assure the spilhvay is adequately sized. Overflow from basins could damage homes as currently designed. Spillways have been provided and have adequate capacity. Note that the design .requires that. overflow spillways discharge to the street. The impact Uf'this condition should be modeled cued indicated See response t0 confluent 26. 29. The drainage design at the steep slope .may result in maintenance problems. The calculated loft -year flows from subcatchment area 5 and 6 are 6.1 and 3.3 efs respectively. This flow could result in scour at the bottom of the slope. Since the swale is proposed to be located within the right-of-way, the Town will be responsible for all maintenance associated with this swale. Details of these swales should be included in the plans. Grate capacity calculations should also tv included in the report to support the design and assure tlo«.' does not by-pass catch basins. Swales have been eliminated and inlets provided. Grate capacity calculations have not been prop: ided. Mler capacities have been provided, hoii-ei-er each of'the inlets are unlikely to capture the Ttldicated capacities. The calculations are based orf an acsutrned depth of flow. AcmaI values should be uutilizcd. Inlet capacity calculations have been modified to represent the actual flow depth conditions. A pass has been indicated at catch basins 7&8, which is not consistent With the model, ho-wever it is unlikel-- to have a significant iinipuct. No furthev comment. 30. Detemion pond 12)'s missing the .174' contour on the uphill side. Satisfactory. 31. Detention pond 17 is missing the 162' contour on the uphill side. Satisfactory. 32. It is unclear where reach 8 is located. The calculations are not consistent with the design in this area. No f I(rther comment. 33. The area Treasured for subcatchment area 1 «vas 6.1 acres. The report uses 5.62. The area should be double checked. Subcatchment areas 5. 6, 8, 13,and 14 were also not consistent with our calculations and should be checked. Satisfactory. %--__-. 7 34. The curve number and areas should be checked for suhcatchment area 13. hood lawn Frith D soil type :should have a CN = 61. mote that the assumption used results in a more conservative design. No further comment. 37. It is unclear if the existing house located in. subcatchment area 14 was included in the calculations. The open space is described as good. however, a Citi of 69 was used. We believe this should be 61. Note that the assumption used results in a more conservative design. Xo further colranent. 36. We recommend that an outlet structure with two openings be used on pond 17 Versus the two pipes over each other. The inlel stn acture to the infiltration basun has been nIodltied to include onlj : one pipe and a FES. We recommend that the outlet apron be constructed of rip- rap for erosion control. The drainage basin ttrodel indicates an inflow of 15.88 CFS. It is unclear doer the proposed 1.5 -inch infer pipe can accommodate this,loir. The pipe calculations' f tr the 140 -_near storm consist of the .same data as the 10 -year .storm. The 100 -year .stone pipe calculations should be revised. 77ae 15" inlet pipe has been changed to 21 ". 77re 21 '' pipe with a slope Uf *l.8% appeaf-s to htrt,e tuleellu7te calxuity. 77ae drairn line profile on sheet i shouhl be upcttrted to reflect this change. The plans have been revised, satisfactorily addressed 37. The sedimentation basin and check dam should be detailed Details have been provided fi)r the check- dorm and sedimentation basin. No frcr tlaer comment. 33. Contours are incomplete at the top of the slope on Lot 2. Complete topography on L,crr 2 has been indicated. However, the topography at the' north end (?f the.site ,should he indicated. No further comment. New comments dated October 4, 1999: to The extent of vegetation renlo-val. which is -required foi- adequate site distance as per the submitted study, should be indicated on the plans. The limit (?f clearing has been, indicated on the pans. Nofifflflef-CD7,zlnent. 0 2, Section 7.}N.)4.) The proposed double catch basin. should be clearly indicated on the Plans. The dorthle catch basins have been indiccued on the plans. h%o fi rther coinitrerit. 3. The ultimate discharee point for the proposed footing drains, sub -drains and curtain drains should be indicated and modeled. A trench drain or Swale should be constructed at the top of the proposed slope, on the southern end of the site. The proposed curtain drains..footing drains rind sub -drains would discharge groundiraler- and could residt in erosion as designed. A foundtaron drama outlet detail has been added to sheet 5. S'atis/actorily addressed. 4. The overflow spillway for Detention Basin Al is indicated as a sharp crested weir and modeled as a broad crested weir. The model has been modified to represent the prolxosed conditions. leo further comment. S. Based on input at public hearings the easterly abutter expressed concern relative to groundwater influence on their basement. The house should be indicated on the plans. A curtain drain is indicated adjacent to this property. The capacity of this drain during storm events should be evaluated. The curtain drtrrn tit the eastern property line has been trande.led. however the proposed infiltration area would include all bottom area below the orrtiet invert. 1V6 f rrther comment. We appreciate the opportunity to assist the Planning Board on this project and hope that this information is sufficient for your needs. We would be pleased to meet with the Board or the design engineer to discuss this project at your convenience. If you have any questions please do not hesitate to contact us. Very truly yours, COLER & COLANTONIO, INC. CC4'e'� - John C. Chessia, P.E. cc: Benjamin C. Osgood, Jr., President Devra Bailen Esq. a J Division of Public Works '384 Osgood Street North Andover, MA 01845 Phone 978-685-0950 Fax 978-688-9573 To: Heidi Griffin, Town Planner From: James Rand, Jr., Director Of CC: J. William Hmurciak, PE, Dire Date: June 4, 2001 Re: Red Gate Pasture Engineer Plan reviewed "Definitive Plan RED GATE PASTURE located in North Andover, MASS" revised 2/26/01 The March 20, 2001 memo from Coler & Colantonio on page 2, 5" paragraph references the DPW on slope stabilization. The engineer has proposed what appears to be a satisfactory solution to the slope stabilization and we have no additional comment. If the revised plan addresses the issues stated in my memo dated January 46, 1998, the plan is satisfactory to us. CNEMOS HEIDIG 2001/REDGATE 6401 0 Page 1