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Home My WebLink About1999-09-08 Civil Review CANT N 2 eN73(NEERS A1'JO SC iEr i-n5 r5 June 28, 1999 Heidi Griffin � Planning Board f "R" Town Hall Annex 27 Charles Street 1 � North Andover, MA 01845 RE: Engineering Reviewt p,NNtiN Brook School Site Plan Dear Ms. Griffin: In response to your request, Coler &c Colantonio, Inc, has reviewed the supplemental submittal package for the above referenced site. Our efforts included a comparison of information submitted with respect to the requirements of the North Andover Zoning Bylaws. In addition, we visited the site on June 24, 1999 to observe existing conditions. The submittal package included the following information: Plans Entitled • "Plan Set for Brooks School- Dining Hall and Campus Center Improvements", located in North Andover, Mass." Prepared by RFS Engineering, consisting of twelve sheets dated 4/30/W and Received June 30, 1999. m "Site Plan Application, Hydrology Report and submittal letter" dated June 1999."Prepared by RFS Engineering and Received June 30, 1999. During our site visit, we observed utility construction in the vicinity of the proposed dining hall. We also traced the relative portions of the drainage system including the outlets to and from the wetland and detention pond. The outlet pipe to the wetland was observed to be approximately 90% submerged. An observation of the existing wetland areas indicated several feet of freeboard to the elevation of Great Pond Road. 101 Accord Park Drive _ 781-982.5400 Norwell, MA 02061-1685 Pax: 781-982-5490 Zabi>zg�ylnw: 1. Section 8.3) 5.) e.)ii) A waiver from the boundary survey is being requested. 2. Section 83) 5.)e.) v.)Proposed spot grades should be included on the plans. 3. Section 8.3) 5.)e.) vii.) The Vortemh Model 5000,which was selected, is note adequately sized for the proposed flows without a bypass manhole. Catch basins Q should not be directly linked.The time of concentration analysis indicates sheet flow � � in excess of 350'. This condition is not consistent with NRCS recommendations for New England. The pre construction peak flows have not been maintained under post ,( construction conditions, however the development will most likely not have.a significant impact on the capacity of the currently proposed system. It is our understanding that this is the first of several developments proposed at this site and the culmination of all these developments may have an impact on the system. It is our recommendation that the entire system is modeled for the final development conditions and the cumulative runoff volumes and flows are indicated as proposals are made. The proposed catch basins are indicated as being linked, it is recommended that they be connected via manholes. All existing catch basins and inverts located within the construction limits should be labeled. 'If 4� Section 8.3) 5.)e.)Ix.)A,waiver from the building height limitation is being W requested. u 5. Section 8.3) 5.)e.) x.)Reportedly, there will be no net increase in the required parking spaces. The Planning Board should review this issue. 6 3 b. Section 8.3) 5_) e_)xi_) It is unclear if a Notice of Intent Application should be filed in conjunction with this application. The location of abutting or impacted wetlands should be indicated. 7. Section 8.3)5.)e.) xvi.)The method and location of refuse enclosure should be indicated, 8. Section 8.3) 5.)e.) xviii.) See comment# 3. j' 9. Section 8.3)5_)e.)xix) Reportedly, there will be no net increase in traffic volumes. The Planning Board should review this issue. 10, Section 8.3) 5.)e.) xxii)Typically reviewed by the town. 11.Section 8.3) 5.) e.) xxiii.)Typically reviewed by the town.. We appreciate the opportunity to assist the Planning Board on this project and hope that ibis information is sufficient for your needs. If you have any questions please do not hesitate to contact us. Very truly yours, COLER & COLANTONIO, INC. hn C. Chessia, P.E. XC: RFS Engineexing Jim Rand,DPW SEP-02-1999 THIS 05: 18 PH COLE' `ND COLANTONIO FAX NO. 7819825490 P. 09/11 COLER F-N,sNr-(-'RR AND 20CNn.I�T3 September 2, 1999 Heidi Griffin Planning Board Town Hail Annex 27 Charles Street North Andover, MA 01845 RE: Supplemental Engineering Review Brook School Site Plan Dear Ms. Griffin: In response to your request, Coler & Colantonio, Inc. has reviewed the supplemental submittal package for the above referenced site. Our efforts included a comparison of inforrtttttion submitted with respect to the retluirements of the North Andover Zoning Bylaws. In addition, we visited the site on June 24, 1999 to observe existing conditions. The submittal package included the following information: Plans Entitled Letter of Response for Brooks School, North Andover dated August 13, 1999. Zoning Bylaw: 1. Section 8.3)5.)e,)ii) A Waiver from the bQL1nda1ry survey is being requested. No further commem. 2. Section 8.3) 5.)e.) v.)Proposed spot grades should be included on the plans. Satisfactorily addressed. 3. Section 8.3) 5.)e.)vii.) The Vortech Model 5000, which was selected, is not adequately sized for the proposed flaws without a bypass manhole. Catch basins should not be directly linked. The time of concentration analysis indicate;, sheet flow in excess of 350'. This condition is not consistent with MRCS recommendations for 101 Accord Park Drive 781-982-5400 Norwell, MA 02061-1685 Pax: 781-982-5490 SEP--02--1999 THU 05' 18 Pal COLEr' '.ND COLANTONIO FAX NO. 7819825490 P. 10/11 t New England. The pre construction peak flows have not been maintained under post Construction conditions, however the development will most likely not have a significant impact on the capacity of the currently proposed system. It is our understanding that this is the first of several developments proposed at this site and the culmination of all these developments inay have an impact on the system. It is our recommendation that the entire system is modeled for the final development conditions and the cumulative runoff"volumes and flows are indicated as proposals are made.The proposed catch basins are indicated as being linked, it is recommended that they be connected via manholes. All existing catch basins and inverts located within the construction limits should be labeled. The selected Vortechnics.system is satisf ictory for the intended use. Catch basin linking, although commonly designed in the past it is►got current standard engineering practice. Due to increased flow velocities and turbulence, upgrades to eliminate link-fd systems should he considered where feasible, Our comment regarding the length vf'sheet flo;v is related ro ti►ne of concentration calculrations.3.50 feet of sheer flow is not standard engineering practice in this area. The Planning Board may ivaive the requirement to model the entire drainage system for this phase of work. 4. Section 8.3)5.) e.) Ix.)A waiver from the building height limitation is being requested. Reportedly, a variance was approved by the ZBA opt August 10, 1999_ 5. Section 8.3)5.)c.)x.)Reportedly, there will be no net increase in the required parking spaces.The Planning Board should review this issue. No fatrther comment. G. Section 8.3) 5.)e.) xi.)It is einclear if a Notice of Intent Application should be filed in conjunction with this application. The location of abutting or impacted wetlands should be indicated. Reportedly, this issue has been discussed and resolved with The Conservation Co►zamission_ 7. Section 8.3) 5.) e.) xvi.)The method and location of refuse enclosure should be indicated. The Planning hoard may choose to waive this requirement. A. Section 8.3)5.)e.)•xviii.)See comment#3. No,further comment. SEP--02--1999 THU 05: 19 PH COLEr 'ND COLANTONIO FAX NO, 7819825490 P. 11/11 9. Section 8.3)5.)e.) xix)Reportedly, there will be no net increase in traffic volumes_ The Planning Board should review this issue, No f irther comment. . 10, Section 8.3) 5.) e,)xxii)Typically previewed by the town. 11. Section 8.3)5.)c.)xxiii.)Typically reviewed by the town. We appreciate the opportunity to assist the Planning )hoard on this project and hope that this information is sufficient for your needs. If you have any questions please do not hesitate to contact us. Very tr«ly yours, ER & COLANTONIO, INC. c John C. Chessia,P.E. XC: RFS Engineering Jim band,DPW