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Village Hill Detention Basin July 30 Wetland Memo M E M O R A N D U M M E M O R A N D U M To: John Perry, PE, Gale Associates From: Sarah LaValley Date: July 30 , 2013 Re: Village Hill Detention Basin #1 , Supplemental Information and Revised Plans Staff have reviewed the NOI materials and subsequent revised plans that have b een submitted to the Conservation Commission for the Village Hill Detention Basin #1 project. A hearing can be scheduled for the next Commission meeting on August 22 , but please be advised that staff will recommend denial of an Order of Conditions based o n the information provided to - date. The project as proposed in the application does not, in the opinion of staff, comply with the performance standards for applicable resource areas established in the Massachusetts Wetlands Protection Act and its Regulat ions, and in the Northampton Wetlands Ordinance. The below list outlines remaining staff concerns, as well as instances where plans and supporting documents do not contain adequate information for the issuance of an Order. 1. A narrative must be provided t hat details how the proposed project meets the riverfront area performance standards of the Rivers Protection Act. Specifically, A complete alternatives analysis must be provided that meets the requirements of 310 CMR 10.58(4)c Your July 16 letter include d only a brief mention o f an alternatives analysis that was not included in application materials. 2. Details regarding the reasoning to classify the unnamed stream as pere nnial are needed. Your July 16 letter indicated that this decision was based on a Mas sGIS map, as well as visual conditions. Neither of these are acceptable methods under the Rivers Protection Act for classifying a stream that is not shown on USGS maps as perennial. Please provide more information about this decision that is consistent w ith 310 CMR 10.58(2)a. 3. As shown, it appears that runoff from the lip spreader will follow the existing drainage pattern, potentially creating scour and erosion within the riverfront area during some storms. Your July 16 letter indicates that peak flow and velocities are reduced up to the 100 - year storm, but any erosion or sediment created or deposited as a result of the project in any size storm would constitute an additional alteration to the resource area. 4. The stormwater report submitted July 16 is b ased on presumed development conditions for the watershed. If impervious areas within the associated development change, the basin may not be appropriate for as - built conditions. If the basin is too large for the development as constructed, it is not app ropriate for the Commission to approve unnecessary disturbance. 5. In the absence of detailed development plans for the watershed, the Commission will not be able to determine whether the project as proposed will result in the dewatering of wetland series B. Your July 16 letter stated that ‘flow to wetland series B will be generally maintained,’ but no plans were provided for the development that will utilize the proposed stormwater basin. 6. This project is subject to the stormwater management standards . As DPW indicated in its stormwater permit denial, LID measures for the proposed project were not submitted, as required by the MA DEP Checklist for Stormwater Report. 7. While the majority of Village Hill is within the Planned Village district, t he portion of t he work that is proposed closest to jurisdictional resource areas in this project is not within this district, and does not have a reduced Protected Zone. A narrative must be provided to demonstrate how the project as proposed meets the performance standa rds of the Northampton Wetlands Ordinance, Chapter 337 - 10 E (2). An Order of Conditions cannot be issued if these performance standards are not met. Your July 16 letter and revised plans reference 337 - 10e(2)d, and states that the work will ‘improve the current state of the buffer zone by providing additional native shrub plantings.’ The work proposed within the Protected Zone includes a large amount of clearing, grading and addition of fill. Including a small number of plantings within an alteration t hat eliminates all existing vegetation and topography does not meet this standard.