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Home My WebLink About1998-10-22 Correspondence Stormwater Pond Replacement Plan 95 Lyons Lana Engineering 4 .,environmental Services, Inc. Environmental eF CONSULTING CIVIL ENGINEERS&LAND SURVEYORS 130 MIDDLESEX ROAD,SUITE 11 rA '°BN°TYNGSBORO,MA 01879 11'[NTi�iti TELEPHONE(978)649-4642 1 FAX(978)649-0981 "'D- /C- TO C/ 2 z;_1 _ = � � WE ARE SENT YOU ❑ Attached ❑ Under separate cover via the following items: ❑ Shop drawings ❑ Prints ❑ Plans ❑ Samples ❑ Specifications ❑ Copy of letter ❑ Change order ❑ ColplEs DINE NO. DESCRIPTION r -3 J le ze 1 V_LIL.114�v).............2L THESE ARE TRANSMITTED as checked below: ❑ For approval ❑ Approved as submitted ❑ Resubmit copies for approval ❑ For your use ❑ Approved as noted ❑ Submit copies for distribution ❑ As requested ❑ Returned for corrections ❑ Return corwtad prints ❑ For review and comment 0 ❑ FOR BIDS DUE 19 ❑ PRINTS RETURNED AFTER LOAN TO US REMARKS COPY T SIGNED. LandEngineering 130 Middlesex Road ! Environmental Services, Inc. Tyngsbor o f MA 01879 f CIVIL ENGINEERING &LAND SURVEYING TELEPHONE(978)649-4642 1 FAX(978)649-0981 1 October 30, 2019 Ms. Monica Gregoire,Staff Planner ` Ms.Amy Maxner,Conservation Administrator Town of North Andover 120 Main Street North Andover, MA 01845 RE: 95 Lyons Way Stormwater Pond Replacement Plan Dear Ms. Gregoire and Ms. Maxner, Enclosed, please find the revised drainage Improvement Plan and Stormwater Pond Replacement Plan � s that have been updated to address the comments from the August 141h Public Works review as follows: 1.- Per the Massachusetts Stormwater handbook,a minimum of 1 test pit per 5,000 feet of infiltration area is required to determine the existing soils and Estimated Seasonal High Groundwater Table (ESHGwT).The test pit shall be observed by a licensed soil evaluator. No testpit information has been submitted for the proposed infiltration area. Two test pits have been witnessed in the area of the proposed pond as shown on the revised plan. The soil evaluation forms are included in the appendix of the updated Stormwater Report. 2. A minimum of a 2 foot separation is required between the ESHGwT and the bottom of the infiltration system.This shall be verified using the test pit information from Comment#1. The test pits confirm that the ESHGWT to be at elevation of 105, two feet below thebottom of the proposed pond. 3. Per the North Andover Stormwater Management and Erosion Control Regulations,the 24-hr rainfall intensity rates to be used for the 2, 10, 25, and 100 year storm events shall be as follows: 2-'yr, 24 hr event=3.2 inches 10-yr, 24 hr event=4.8 inches 25--yr,24 hr event 6.0 inches 100-yr,24 hr event=8.6 inches The proposed HyrdoCAD drainage calculations shall be updated using these rainfall intensity rates and the design adjusted accordingly. The revised HydroCAD calculations have been prepared using the above rainfall intensity rates., i i { I 1 4. Page 5 of the Stormwater Pond replacement Plan report identifies the following: "Culvert flow calculations contained in the Closed Drainage Computation Worksheet in the appendix were performed using the Rational Method." There does not appear to be any culvert flow calculations included in the appendix. The Closed Drainage Computation Worksheet has been included in the appendix of the revised Stormwater Report. 5. The HydroCAD calculations do not appear to evaluate the proposed 24--inch HDPE inlet pipe that connects the forebay area to the proposed Cultec chambers.This pipe needs to be evaluated in the drainage calculations. The proposed 24"HDPF pipe has been added to the HydroCAD model and is included in the Closed Drainage Computation Worksheet. , I 6. Per the Massachusetts Stormwater Handbook,an evaluation of the draw downtime shall be calculated to confirm the Cultec chambers empty fully within 72--hours of the end of a storm event. I The Applicants Engineer shall provide these calculations. f The proposed pond drains in 67.5 hours has shown in the revised Stormwater Report. I, 7. The Operation and Maintenance plan shall be updated to include a restriction that no structures of any kind including but not limited to trees and or plantings with a substantial root system other than grass shall be allowed to be planted above the infiltration chamber area in perpetuity. Furthermore,the Conservation Commission may want to consider including a similar restriction within the order of Conditions for the lifetime of the property. The operation and Maintenance Plan has been so revised. 8. According to the Outlet Control Structure detail,the top elevation of the weir is equal to 110.45 and the proposed rim of the manhole cover is equal to elevation 111.50. This leaves approximately 12 inches between the top of the weir and the top of the manhole cover.A manhole cover and frame are typically 8 inches and a manhole concrete flat top is typically 6 inches thick totaling a minimum of 14 inches being required:There does not appear to be sufficient depth from the top of the weir to the rim ❑f the manhole cover.These dimensions and elevations shall be verified. The Cutlet Control Structure has been revised to provide three feet from the top of the weir to the rim of the structure. Thank you for the opportunity to address these comments and please feel free to contact me if you have any questions. Sincerely g ee cc: Richard & Robin O'Neill letter of Transmittal NORSE ENVIRONMENTAL SERVICES, INC. Date: November 1, 2019 92 Middlesex Road—Suite 4 Tyngsboro, MA 01879 TEL: (978)649-9932 FAX: (978)649-7582 www.norseenvironmental@verizon.net To: North Andover Planning Department From: Maureen Herald Ms.Monica Gregoire Pages: Re: 95 Lyons Way—No.Andover—DEP File No.242-1762 Date: November 1,2019 ❑ Urgent For Review ❑ Please Comment O Please Reply ❑ Please Recycle Please see the enclosed LEES letter, Stormwater Pond Replacement Plan & Drainage Improvement Plan latest revision date 10-30-19. Sincerely, Maureen Herald, PWS TOWN OF NORTH ANDOVER DIVISION OF PUBLIC WORKS 384 OSGOOD STREET NORTH ANDOVER,MASS ACHUSETTS 0 1845-2909 JIM STANFORD DIRECTOR John J. Borgesi PE Telephone (978) 68'5-0950 DII-ector ofEngineering Fax(978) 688-9573 November 20, 2019 Ms. Monica Gregoire Ms. Amy Maxner Staff Planner/Conservation Agent Town of North Andover 120 Main Street North Andover, MA 0 1845 RE: 95 Lyons Street Re iced Stormwater Pond Replacement Plan Dear Monica/Amy As requested, the Engineering Department has reviewed the comment response letter dated October 30, 20191 that included a revised Stor,mwater Pond Replacement Plan, revised drainage caiculations, and a revised drainage improvement site plan for the project located at 95 Lyons Street as prepared by Land Engineering & Environmental Services, Inc. and submitted on behalf of Richard & Robin Lynne O'Neill. Based on my review all of my original comments from a letter dated August 17, 2019 have been adequately addressed. Given the nature of the project, I recommend that an engineer's certification letter and an as-built plan that includes surveyed elevations of the infiltration chambers, stone bedding, stone cover, outlet control structures, pipe inverts, etc. that is stamped and certified by a registered professional engineer be conditioned as, a requirement of the permit approvals. Please do not hesitate to call if you have any questions. Sin hn, J. Borgesi, P.E. Town Engineer Cc file