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HomeMy WebLinkAbout2011-10-04 Planning Board Supplemental Materials (9) Enright, Jean From:Tymon, Judy Sent:Tuesday, October 04, 2011 1:32 PM To:Enright, Jean Subject:FW: 2009 Salem St. revisions Jean, Could you put this in the packet and also make a copy for the Board. Thanks. Judy From: Lisa Eggleston [mailto:lisa@egglestonenvironmental.com] Sent: Tuesday, October 04, 2011 1:15 PM To: Tymon, Judy; Hughes, Jennifer Cc: Merrimack Engineering Subject: 2009 Salem St. revisions Hi Judy, Following up on our conversation earlier today, I have reviewed the 9/15/11 revisions for the 2009 Salem St. project. I also received a copy of the 9/30/11 Notice of Intent filing for the project. As I indicated to you, the design revisions address most of my previous comments. My outstanding/additional comments are outlined as follows: As discussed with Bill Dufresne in our phone conversation today, I do recommend that check 1. dams be added to the drainage trench to slow the rate of flow down the slope of the trench and promote infiltration. Periodic maintenance of the check dams will also be needed. The North Andover Wetland regulations call for hydrologic analysis of the 1-yr storm and also 2. require that runoff volumes (not just peak rates) be addressed. The project actually does a decent job of maintaining the existing hydrology of the site, so I'm not sure that these additional analyses are really necessary. The one recommendation I do have is that the roof dry well on Lot 1 be shifted to the back of the house, hence the other side of the ridge line from where it is currently shown. Assuming that groundwater flow on the site is more or less consistent with surface drainage, this would help to maintain the recharge that is tributary to the vernal pool. It appears that this project will entail more than an acre of land disturbance and will therefore 3. be subject to coverage under the EPA Construction General Permit. A Stormwater Pollution Prevention Plan (SWPPP) will be required prior to initiation of land disturbance that will expand on the erosion and sediment controls currently proposed. In particular, the SWPPP should address the sequencing of the construction to minimize exposed slopes and protection of areas proposed for infiltration. I also recommend the addition of a stabilized construction entrance to prevent sediment tracking onto Salem St. Hope this helps in terms of your discussion tonight. Please let me know if you have any questions. Lisa D. Eggleston, P.E. Eggleston Environmental 1 Please note our new mailing address: 32 Old Framingham Rd., Unit #29 Sudbury, MA 01776 tel 508.259.1137 fax 866.820.7840 lisa@egglestonenvironmental.com Please note the Massachusetts Secretary of State's office has determined that most emails to and from municipal offices and officials are public records. For more information please refer to: http://www.sec.state.ma.us/pre/preidx.htm. Please consider the environment before printing this email. 2