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HomeMy WebLinkAbout739 Rte 149 Accessory. NOI.12.19.25 1 PROJECT NARRATIVE – 739 Rte. 149 – Accessory Building Alterations The area subject to this notice is land near the west-facing shore of Hamblin’s Pond. Marstons Mills. Please see the locus maps for the exact location. The site is an elevated, wooded, residential parcel with earth surface driveway, an existing residence, open decks, with 2 accessory buildings. One, a small storage shed and the second is a detached garage. This detached garage structure is the focus of the Notice of Intent application. The building and work area are in the buffer zone stemming from the Inland Bank associated with Hamblin’s Pond. Wetland resources of note are the Inland Bank which is a sharp, discernable scarp feature confining the pond during times of high-water table. Closer to the pond water from the Inland Bank is the gravelly inland beach and waters of Hamblin Pond. The site characteristics include a soil quality which is an excessively – to - well-drained, gravelly sand, consistent with outwash plain deposits with a long-developed, forested surrounding land area. A hydric depression exists on locus, much closer to Rte. 149, well distant from the project area. The proposed work activity subject to this NOI is approximately 300 fl. from the described low area. The work site is within a mapped Priority Habitat for Rare and Endangered Species. A copy of the NOI application shall be filed with NHESP. Specifically, the existing garage accessory building is located partially within the 50 fl. buffer to the Inland bank with the remainder being within the 100 fl. buffer The Proposed Activities. The existing detached garage building is proposed to be modified to become a single bedroom, accessory dwelling unit with the garage bay remaining as is. The alteration includes a second floor, two 2 fl. cantilever bump-outs on two sides, a 4 fl. X 12 fl. cantilever deck on the pond side and an egress staircase on the side opposite the pond. The foundation shall be enhanced 2 with helical piles. The helical piles require some work within the garage with some localized , shallow (approx. 2 fl. depth) excavation outside directly adjacent to the building for each pile localized to each discreet anchor location. Design efforts were made to minimize work that would alter the ground. The work activity to perform the tasks will require access around the building and a work limit is proposed to confine this activity. Water, electrical trenching will be within the existing altered driveway area. The building shall be served by the existing subsurface sewage disposal system currently serving the main house, augmented with a separate independent septic tank expressly for the ADU. The septic tank will discharge the flow to an existing pump chamber that will convey the eftfuent to the existing SAS. The foot traffic and alteration for foundation enhancement is temporary. The building segments extending outward from the existing structure are 8 fl. above the ground with exception of the open riser egress stairs. The elevated extensions ( 2 cantilever bump-outs and cantilever deck) account for a total 144 s.f.; the egress stairs account for 56 s.f. Of this total of 200 s.f., 16 s.f. of elevated, cantilevered building and the 48 s.f. cantilevered deck are within the 50 fl. buffer with the remaining building alteration of 136 s.f. within the 100 fl. buffer. We understand the Commission interprets the described elevated building alterations to require mitigation and the accounting goes as follows: MITIGATION - Section 704-4 of the Barnstable Regulations Governing Activity in the 100 fl. Buffer Zone relating to alteration within the 50 fl. buffer addresses waivers for such activities as described in this application. Interpretation of the 136 s.f. within the 50 fl. to 100 fl. buffer as alteration requiring mitigation then the applicant must target an applicable area for a planting program of 408 s.f. Accounting for the 64 s.f. of alteration in the 50 fl. buffer results in 256 additional s.f. for a total mitigation program of 664 s.f. Unlike formally prepared and artificially landscaped sites that the Commission has great amount of experience with, this site possesses no lawn, no large cleared zones and is for the most part kept in an informal, natural state. The existing site conditions, building placement location and use areas stem from an earlier time. We reviewed with the applicant opportunities for on-site mitigation and the applicant’s conclusion was that there were no practical locations for vegetative enhancement and that off-site mitigation might be viewed by the Commission as a more valuable option in this instance. Off-site Mitigation Requirements to be Considered a. The Commission must find that the project site is "mitigation-constrained". It appears to be. 3 b. the applicant/representative must request in writing that the Commission consider off-site mitigation for the project. The request is made herein. c. when off-site mitigation is proposed the applicant/representative must identify the proposed off-site mitigation location and demonstrate the property owner’s consent to (a) use of the property for this purpose and (b) record an Order of Conditions and Certificate of Compliance, or similar legally binding restriction on the off-site mitigation property for this purpose. The applicant believes in-lieu fee will be a practical option in this instance. d. When off-site mitigation is proposed the area of required mitigation planting is calculated as set forth in 704-3D for work proposed within the 50 fl. to 100 fl. buffer zone, and as set forth in 704-4B(1) for work proposed within the 50 fl. buffer zone. The numerical mitigation accounting above is based on the preliminary assumption that all building expansion values, although largely elevated above grade, will trigger mitigation, and is in accordance with the referenced section, if accepted by the Commission, can be translated directly into an in-lieu dollar amount: 664 s.f. X $3.50 = $2,324 e. The acceptance of off-site mitigation is at the sole discretion of the Commission. The applicant is aware of this. IMAGES OF 739 RTE 149 – ACCESSORY BUILDING SITE October 2025 Figure 1 – View of the existing shed and buffer zone side of the accessory building. Figure 2 – Driveway side of the accessory building Figure 3 – Rear corner of the accessory building in a typical helical anchor location Figure 4 – work staging area to the driveway side of the accessory building, corner is to the right.