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HomeMy WebLinkAbout1999-11-19 Peer Review & O&M Plan SEP--23-1999 MU 04:3b PH COLER AND COLAN'1'ON10 FAX NO. r81992U490 P. 02/03 COLER COLAN I ON10 7. trnFC;�NEEtiC ANf_1 �i[;fhnJTIST.n September 23, 1999 Hcidi Griffin Planning Board Town Hall Annex 27 Charles Street North Andover,MA 01845 RE: Engineering Review Brooks School-Proposed Maintenance Building Site Plin bear Ms. Griffin: In response to your request, Coler& Colantonio, Inc. has reviewed the 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. The submittal package included the following information: Plans Entitled • "Plan Set for Brooks School- Maintenance Building", located in North Andover, Mass." Prepared by RPS Engineering, consisting of four sheets dated 9/3/99 and Received 9/7/99- • "Site Plan Application, Hydrology Report and submittal letter" dated 9/99," Prepared by RFS Engineering and Received 9/7/99. Zoning Bylaw: 1. Section 8.3)S.)e,)ii) A waiver from the boundary survey is being requested. 2. Section 8.3) 5.)e.)vii)The pre construction peal: 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 cuirently proposed system. It is our understanding that this is the second 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 tnodelcd for the final development conditions and the cumulative runoff volumes and flows arc indicated as proposals are made. The proposed system should be modeled for the 2, 10 and 100-year storms. 101 Accord Park Drive 781-982-5400 Norwell, MA 0206 1-1 685 Fax: 781-982-5490 SEP -23-18y9 MU 04:35 FM COL1 k AND GOLANFON10 FAX NO. 131982bO0 P, 03/03 Test pits should be performed, in the vicinity of the infiltration system and building cellar,by a licensed soil evaluator to determine separation to high groundwater. Sheet flows in excess of M-feet have been assumed. This condition is not consistent with MRCS recommendations for New England.The configuration of the proposed drainage system will not provide efficient flow conditions. We note an angle sharper than 90-degrees. In addition, the proposed catch basins are indicated as being linked, it is recommended that they be connected via manholes. A 4-foot sump is required for proper TSS removal. The method of sealing and securing the proposed oil/debris hoods is unclear. 3. 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. 4. Section 8.3) .5.)a,)xi.) it is unclear if a Notice of Intent Application should be filed in conjunction with this application. 5. Section 8.3) 5.)e.)xvi.)The method of refuse enclosure should be indicated. G. Section 83) 5.)c.)xix) A waiver from the traffic study is being requested.. 7. Section 8.3) 5.)e.)xxii)Typically reviewed by the town. 8_ Section 8.3)5.)e.) xxiii.)Typically reviewed by the town. f We appreciate the opportunity to assist the Planning Board 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 truly yours, COLER &COLANTONI.O, INC. e au� hn C. Chessia, P.E. XC_ RFS Engineering Jim Rand,DPW .RFSsHUMWAY RIST-FROST-SHUMWAY ENGINEERING,P.C. CONSULTING ENGINEERS November 4, 1999 RFS 199-4162 Mr. John Chessia, P.E. Cofer& Colantonio, Inc. 101 Accord Park Drive Norwell, MA 02061 RE: Test Pit- Maintenance Building Brooks School Dear Mr. Chessia: In your letter of 9/23/99, you requested a test pit at the site to confirm the groundwater table in regards to the recharge requirement. On Thursday October 14, 1999, a test pit was dug by backhoe approximately 7' deep in the location shown on the attached partial copy of the site plan. It was allowed to stabilize overnight and the water table was measured at 4' below grade the following morning. See attached photographs. The infiltration trenches will be 2 feet deep, so their bottoms will be 2 feet above water table as required. Two other facts are pertinent. (1) The building will not have a basement; it will be a slab on grade. (2) The adjacent area was the long-time subsurface leach field for the school, so the soils have been shown to be permeable. The field was discontinued in 1987 when a pump station and force main were constructed to connect to the municipal sewer system. We trust this satisfies your request. Sincerely, ST-FR S SHUMWAY ENGINEERING, P.C. o L. Scott, P.E. e 'or Civil Engineer J :jds JLS W 162 U Ch essia.110499J.w pd Enclosures cc: Heidi Griffin, NAPB✓! Mike Farnola, DTI 71 WATER STREET • LACONIA, NH.03246 0 TELEPHONE 603.524-4647 • FAX 603.528.7653 rfs@rfsengineering.com ry I Y � > z n 1 Y F j - } AKIL �T u� muu RFSSHUMWAV RIST-MOST-SHUMWAY ENGINEERING, P.G. CONSULTING ENGINEERS October 13, 1999 RFS 199-4162 Ms. Heidi Griffin North Andover Planning Dept. 27 Charles Street North Andover, MA 01845 RE: Responses to Review Comments Maintenance Building Brooks School Dear Ms. Griffin: On October 5, 1999 we appeared before the Planning Board to present and discuss the new Maintenance Building project. In response to comments received from the Board, we offer the following: 0 We have added landscaping plantings. ® We are submitting the operation and maintenance plan for our stormwater treatment devices for your review. Enclosed are nine (9) sets of revised site plans (the architectural plan is unchanged). In addition to the plantings, please note that we have made the following refinements, at the school's request: (a) removed grass strip along southerly fence as it will be difficult to mow neatly, (b) added one new sliding gate to the fence around the yard, (c) added a light pole for the parking area near a corner of the building, and (d) widened Service Road at the garage by one foot. We also offer the following responses to the comments of your consultant, Coler&Colantonio, Inc. of 9/23/99. A copy of this letter,with enclosures, is being sent to them. Using their numbering, 1. No response required. 2.a. We will be preparing a master drainage plan for the Campus Center/Dining Hall, Maintenance Building, and Athletic Facility projects as a condition for the occupancy permit for the Dining Hall as per the Notice of Decision of 9/8/99. This plan will include a detention facility sized to meet the peak attenuation standard for all three projects in aggregate. 2.b. We have modeled the Maintenance Building drainage system for 2, 10,and 100 year storms. Performance is satisfactory. Revised drainage calculations are enclosed, which include the changes mentioned above. 2.c. Arrangements are being made for a test pit in the vicinity of the infiltration trenches. We expect to have results in time for our scheduled 10/19/99 meeting with the Board. (Note: the building will not have a cellar—it is slab- on-grade construction). 71 WATER STREET LACONIA, NH•03246 ® TELEPHONE 603-524-4647 e FAX 603.526-7653 * rfS((i)rfvorigineE:riiig.cotrI muuuuomoiomourvvuuomwwww.uw.wwwwwmumm r 1fWW�pp�pp��1 RFSSUM' IIIIII.# WAY Ms. Heidi Griffin October 13, 1999 North Andover Planning Dept. RFS 199-4162 Responses to Review Comments Maintenance Building Brooks School 2.d. Don't you mean 300 feet instead of 100 feet? At any rate, the long stretches of sheet runoff are existing conditions which have performed satisfactorily over time. We request they be allowed to remain. 2,e. We believe the configuration of linked catch basins is routinely accepted throughout New England. The site is confined, and adding drain manholes would create some underground congestion. 2.f. We have changed depth of sump to 4 feet. 2.g. The manufacturer of"The Snout"catch basin hood informs us that they use a very resilient gasket made of ruptured cell nitrile pvc which adheres to the hood by adhesive. The gasketed hood then attaches to the catch basin wall with 3/8"stainless steel bolts and cinch anchors. A hood for a 12"pipe uses six bolts. They claim that the gasket will seal tightly even to old brick- and-mortar catch basins. 3. We have submitted a campus-wide parking plan which the Town has accepted. 4. We have filed a Notice of Intent and are scheduled for a public hearing on 10/20/99 with the Conservation Commission. 5. The entire maintenance yard area, including the refuse area, will be inside the 8-foot vertical slat fence, thus shielding it from view. 6.,7,, and 8. No responses required. We look forward to meeting with you and the Board again on October 19, 1999. Sincerely, RIST-FROST-SHt1MWA"Y ENGINEERING, P.C. 3 n L. Scott, P.E. S nior Civil Engineer J Sjds SW 1621HGtfffin.9093991 wpd cc: B. Wallin, Brooks School M, Farnola, DTI J. Chessia, Coler& Colantonio, Inc. Enclosure(s) Operation and Maintenance Plan Post-Development Stormwater Controls for the New Maintenance Building at Brooks School Stormwater Controls for this project consist of one`Downstream Defender" stormwater treatment device and hoods on all catch basins in the maintenance yard and adjacent parking lot. The Downstream Defender is located at the edge of Service Road just north of the building. It is a buried concrete structure accessed via manhole cover. There are two catch basins in the maintenance yard and two catch basins in the parking lot. Brooks School is the owner of the control devices and is responsible for their operation and maintenance. Downstream Defender Maintenance A sump vac is used to remove captured sediment and floatables. Access ports are located in the top of the manhole. The floatables access port is above the outer annular space between the dip plate and the manhole wall, where floatables are retained. The sediment removal access port is located directly over the hollow center shaft which leads to the sediment storage facility below the vortex chamber. Floatables and oil should be removed prior to the removal of the sediment. The frequency of the sump vac procedure is best determined in the field after installation. During the first year of operation, the unit should be inspected every b months to determine the rate of sediment and floatables accumulation. A probe can be used to determine the level of solids in the sediment storage facility. This information can then be used to establish a maintenance schedule. When sediment depth has accumulated to 1.5 feet, or floatables depth reaches 6 inches (whichever occurs first), the contents should be removed by sump vac. Although a small amount of water is removed along with the pollutants during the clean out process, the units are typically not completely dewatered. A Downstream Defender with 1.5 feet sediment depth removes about 400 gallons of water in the process. Disposal should be to a publically-owned wastewater treatment facility. Hooded Catch Basin Maintenance. At the same frequency as the Downstream Defender maintenance, each catch basin should be fully cleaned. Disposal should be as for the Downstream Defender.