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Home My WebLink About2016/11/02 - Eggleston Environmental Stormwater Review - 30 Ironwood Road muuuuu les�ta��n m a uu 7 lumlmm "'it, puuNp'' puuu �� uuuuu Iu° ull °°uu+�m»aiauaia��a1011/ll0/l1/llllll��r!��U' November 2, 2016 North Andover Planning Board 1600 Osgood Street North Andover, MA 01845 Attn: Rebecca Oldham, Staff Planner RE: Watershed Special Permit 30 Ironwood Road Dear Ms. Oldham and Board Members: Per your request, I have reviewed the October 2016 Watershed Special Permit Application packet for the above-referenced project. Included in the materials I received and reviewed were the following: ■ Special Permit — Watershed Permit Application, 30 Ironwood Road, John J & Kara M. Guinee, Petitioners ■ Plan to Accompany Notice of Intent in No. Andover MA Showing Proposed Improvements #30 Ironwood Road (Lot 5), prepared by Hayes Engineering, Inc. and dated August 22, 2016, revised October 3, 2016. I also conducted a brief site visit to observe existing drainage patterns. My primary focus in this technical review is on the overall stormwater management approach and design concepts used in the project, as well as its compliance with the Town of North Andover's zoning requirements for Watershed Protection Districts. The project site is an approximately one-acre lot at the northern end of Ironwood Road. It is currently developed with a single-family home, driveway, and lawn areas. Existing drainage on the site is overland in a northerly direction toward an onsite bordering vegetated wetland (BVW). The proposed project calls for extending the existing paved driveway, replacing an existing patio and adding a new patio, and construction of several retaining walls and landscape areas. The plan calls for a new 4-in PVC drain to collect runoff from the new patio area with discharge toward the BVW via a level spreader. All of the proposed work area is within the 100-ft wetland buffer to the BVW. Since the BVW is tributary to Lake Cochichewick the work is also entirely within the Non- Disturbance Zone of the Watershed Protection District. The lot was created prior to October 24, 1994, so the Conservation Zone restrictions of the Watershed Protection District do not apply. �uu�� uu�� pm w u uu�lu m uuu�lp�IpVi�' iiu�� uuuu�� vu� �� i iu�� i liu�� ql Ili, IIIII ��I��III I��V � Vlu'��ii�� w �w �u�� W 9 4 4 I lJ ��uuu�.��mI�IP�� °�� u" ��iiii� iii��iiii iiii�� iiii�� ulu��iiii�� ul�� :�u� a ��:iiiii I� �III ��I II�� ,ml ��u �� uI� "��ml�� ul 'i 1i o "l V au i , oill e My comments on the application are outlined below: 1. All applicable watershed protection zone boundaries need to be identified on the plan. 2. In accordance with Section 4.136 of the Zoning Bylaw the proposed project is an allowable use in the Non-Disturbance Zone, however the application also requires proof that there is no reasonable alternative outside of the Non-Disturbance Zone for the proposed activities; this was not included in the application materials I received. 3. Per the Special Permit Requirements of the Watershed Protection District any runoff from impervious surfaces within the Non-Disturbance and Non-Discharge Zones must be recharged onsite or, where recharge is infeasible, other BMPs be employed. The narrative accompanying the application for this project references pervious pavers being used to reconstruct the existing patio and a stone infiltration trench to collect driveway runoff, however no design details or calculations have been provided and none of these measures are shown on the plan. The NRCS soil maps indicate that the soils on the site are highly suitable for infiltration therefore all of the new/reconstructed impervious area associated with the project should be able to be recharged on site and the proposed surface discharge should not be needed. 4. Also per the Special Permit Requirements, a written certification by a Professional Engineer or qualified hydrologist or hydrogeologist is needed, stating that there will not be any significant degradation of the quality or quantity of water in or entering Lake Cochichewick. 5. The limit of work, including vegetation clearing, should be shown on the site plan in accordance with the Special Permit requirements, and the proposed landscaping should be described. I recommend that the creation of new lawn area be limited to that which is absolutely necessary, and that any new landscape area be constructed in such a manner as to minimize the maintenance that is required, e.g. the soil should be well aerated, it should have a minimum of 6-inches of topsoil and, where possible, native vegetation should be planted to minimize the need for fertilizer and watering. The use of fertilizers and other landscape chemicals on the site should be limited to organic, slow-release and low-phosphorus products. As with similar projects permitted within the Watershed Protection District, the limits of approved clearing and the restriction on lawn care products should be permanently recorded on the deed to the property. 6. I also recommend that the use of coal tar-based pavement sealants be prohibited on the property, as they have been determined to contribute high levels of polycyclic aromatic hydrocarbons (PAHs) to stormwater runoff. I �. I i � �I P � Ip 7. Ongoing maintenance of any proposed stormwater management structures should be addressed. 8. A Construction Sequence aimed at minimizing the total area and duration of soil disturbance should be provided. I appreciate the opportunity to assist the North Andover Planning Board with the review of this project, and hope that this information is suitable for your needs. Please feel free to contact me if you or the applicants have any questions regarding the issues addressed herein. Sincerely, EGGLESTON ENVIRONMENTAL Lisa D. Eggleston, P.E.