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HomeMy WebLinkAbout1985-11-12 Stmwtr Review-Margaret Cir.-Response to Peer Review Comments 10/27/2011 GP Civil & Structural Engineering ® Land Planning Land Surveying Engineering Solutions for Land & Structures October 27, 2011 North Andover Planning Board (Attn: Judy Tymon, Town Planner) North Andover Conservation Commission (Attn. Jennifer Hughes, Conservation Coordinator) 1600 Osgood Street North Andover, MA 01846 Re; Stormwater Management Review Definitive Subdivision Plan for Margaret Circle, Off Berry Street Response to Peer Review Comments Dear Ms. Tymon and Ms. Hughes: Goldsmith, Prest& Ringwall, Inc. (GPR) on behalf of our client, Margaret Fiore (Applicant), submits the following response to the comments submitted to the Board by the Board's stormwater management review engineer, Eggleston Environmental, dated October 12, 2011. This response is addition to revised Definitive Subdivision Permit flans, Sewer Extension Permit Plans and revised Stormwater Management Report. For ease of comparison, the responses follow the same format as the comments. 1. No response required. 2. The Stormwater Management Report has been revised to include drainage calculations for the 1-year storm event. 3. The Stormwater Management Report as been revised to include areas that drain from the property to the east into either the proposed Bioretention Area or into the proposed 12" culvert underneath Margaret Circle. The extents of the additional area was determined from the Oakwood Definitive Subdivision Plans' (now known as Windsor Lane),which includes a topographic survey prior to construction. The cover types of the additional area was determined using aerial imagery. 4. The Stormwater Management Report has been revised to treat the Bio-Retention Area and Infiltration Basin as impervious. The report has also been revised to include a drainage analysis for a 30-hour time period. 5. The Stormwater Management Report has been revised to model all grassed areas on the property as "good" condition in both the pre- and post-development models. 6. As stated in the review comment, it is indeed our intention to meet Pear Rate Attenuation (Standard 2) and Stormwater Recharge (Standard 3)for all lots through the roadway "Definitive Subdivision Plan of`Oakwood' loeated in North Andover, Massachusetts"Prepared for Flintlock Realty Trust by Thomas E.Neves Associates,Inc. Dated November 12, 1985;Revised thru February 28, 1986. North Essex Registry of Deeds Plan No, 10252. Goldsmith, Prest & Ringwall, Inc. 39 Main Street, Suite 301, Ayer, MA 01432 0 (978) 772-1590 a Fax (978) 772-1591 info@gpr-inc,com ® www.gpr-inc.com stormwater management system. The proposed Raingardens on Lots 1-5 and the Wet Swale on Lot 7 have been removed from the drainage analysis in the Stormwater Management Report to insure that these requirement are met regardless of individual lot designs. 7. The Infiltration Basin has been redesigned to have 1.00 foot of freeboard during the 100-- year storm event. 8. The Infiltration Basin has been redesigned to be set back a minimum of 50 feet from the edge of wetland. 9. The measurements in the USGS monitoring well data refer to the distance to groundwater from the top of the well, therefore groundwater levels were near their highest at the time of the testing. However, we agree that soil mottling should be used to determine estimated seasonal high groundwater levels and that confirmatory soil tests should be conducted prior to construction. 10. A 12-Inch layer of soil media (50% sand & 50% loam) has been incorporated into the base of the Biofilter Swale. 11. The Bioretention Area detail in the Permit Plans has been revised to show 6-Inch underdra€ns. 12. We have proposed a bituminous concrete curb to be set underneath the top course at the inside of the cul-de-sac to protect the inside pavement edge (see "Reinforced Pavement Edge"detail on Sheet C8.2). The fabric around the 2"-minus washed stone has been removed to eliminate the threat of clogging. The filter fabric separating the two stone layers remains to allow for any sediment reaching the stone diaphragm to be collected, and it's maintenance is now included in the Operations & Maintenance Plan. 13. As we have set the outlet for the Bioretention Area at a minimum elevation and can not lower the underdrain further, therefore we can not increase the depth of soil media. We have revised the B€oretention Area detail to include more specific plantings which includes only shallow rooted shrubs. We feel as though the two feet of soil media will be sufficient for the selected shrubs. 14. The intention is for the proposed roadway, drainage system (along with Parcel A) and pump station (along with Parcel B) to be accepted by the town. We feel as though while the drainage system is not a traditional curb and gutter system, it is low maintenance and easily accessible. 15. The Operations & Maintenance Plan has been revised to address snow plowing on the site. 16. We are not including the BMP's on individual lots in this Operations & Maintenance Plan as each homeowner will be responsible for the maintenance of any BMP on their lot and our Intention is for the town to accept the roadway drainage system. I n addition, the selection of BMP and method of water quality treatment on each Individual lot may change depending on how each lot is designed. 17. A Log Form as been added to the Operations & Maintenace Plan. 18. GPR is in agreement that the Planning Board and Conservation Commission should be provided the opportunity to review the Construction SWPPP. Please review the above information along with the revised materials, If there are questions regarding this information, do not hesitate to contact this office. Sincerely, Goldsmith, Prest & Ringwall, Inc. Matthew K, Bombacl, P.E. 2 GOLDSMITH, PREST & RINGWALL, INC.