11/13/2025 CONSERVATION COMMISSION Minutes (2)

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Town of Mashpee Conservation Commission 16 Great Neck Road North Mashpee, MA 02649 Nitrogen Credits, Planting Heights, and Flow Between Retaining Walls Mr. Colombo then referenced the documentation on offset lands and nitrogen-loading credits in the file, noting there appeared to be two sets of documents, one associated with the septic and one with the house. Attorney Brodsky clarified: • Both the house project and the septic project rely on the same off-site nitrogen-credit parcel. • The nitrogen credits are tied to one lot, so they cannot be double used; practically, only one Order of Conditions will be utilized for actual construction, and the projects are functionally linked. Chair Cook then followed up with Mr. Garelli on the proposed bayberry plantings between the two retaining walls. He asked about the anticipated height of these shrubs. Mr. Garelli responded: • Under ideal conditions, northern bayberry can reach up to nine feet. • In local coastal conditions (wind exposure, etc.), they typically grow to about six feet, still providing a substantial buffer and visual screen. • The plantings will also serve as a food source for wildlife. Chair Cook asked whether the roughly four-foot gap between the two retaining walls raised any concern about stormwater being channeled between them during a flood event. Mr. Garelli explained that: • Project engineer Chuck Rowland had evaluated this issue and concluded that the dominant condition is still-water rise, not strong directional flow across the site. • Any directional flow would more likely follow the roadways, and the abutter's elevated property and existing wall would largely intercept it. • Based on Mr. Rowland's analysis, there is no expectation of significant front-to-back flow through the corridor between the two walls. Recommendations: A three-year mitigation monitoring period for the plantings, given the scope of mitigation. The Commission also discussed the need to ensure that the plans and conditions accurately reflect the revised design: • The foundation plans must clearly indicate that the area under the structure will be finished with gravel, not concrete. • The architectural elevations should be coordinated to show the flood vents that appear on the foundation and piling plans so that all plan sets are consistent going forward. MOTION: To close an issue at 5 Deans Hollow Road with the following conditions: 1. Three-year mitigation monitoring plan; and 2. Gravel under structure. Motion by: Richard Sahl Seconded by: Sandi Godfrey Vote: Motion passed by unanimous vote. (Steven Cook, Paul Colombo, Sandi Godfrey, Richard Sahl) 13