08/21/2025 CONSERVATION COMMISSION Minutes

Home Browse Search

Town of Mashpee Conservation Commission 16 Great Neck Road North Mashpee, MA 02649 NOI 22 Triton Way, Karen Griffin. Proposed repair to an existing revetment wall section (Representative: Cape & Islands Engineering, Inc.) 43- 3359 Homeowner was represented by Mark Dibb of Cape and Islands Engineering. The proposal sought approval to repair a failing section of an existing revetment wall. Mr. Dibb explained that the deteriorating area, located just east of a licensed concrete wall structure, had become unstable, with large boulders shifting and posing safety risks. The goal, he said, was to stabilize the shoreline by replacing the collapsed boulders with a properly engineered riprap revetment. Mr. Dibb distributed photographs showing the current condition and past appearance of the site, noting that the original structure was steep and poorly constructed—essentially a vertical stack of rocks that had inevitably failed over the past two decades. He explained that while a Chapter 91 license had been issued in 2007 for the lower concrete bulkhead and steel sheet pile wall, there were few records predating that license to clarify when or how the upper rock structure had been built. Still,he emphasized that all parties agreed it now needed reconstruction. The proposed design called for a riprap revetment with a stable 1:1.5 slope, tying into adjacent properties' revetments to create a continuous, uniform shoreline. The gray-shaded area on the submitted plan represented the new riprap section, which would start at the existing concrete bulkhead and slope upward to meet the neighboring elevations. A small yellow section on the plan indicated a transition slope connecting the new revetment to the existing adjacent one. Work would be performed entirely from barges due to lack of land access for heavy machinery, ensuring minimal disturbance to the coastal bank and surrounding property. 22 Triton Way- Commission Questions and Design Clarifications Ms. Thornbrugh began by acknowledging the project's safety importance but questioned whether simply replacing the failed section was sufficient for long-term stability. She noted that the flat, concrete portion extending beyond neighboring properties might continue to accelerate erosion and asked why the design did not include removal of the entire concrete face to create a consistent slope along the shoreline. Mr. Dibb explained that the existing concrete wall was a licensed, engineered structure that the homeowner did not wish to remove. Doing so,he said, would require significant excavation closer to the house and could disturb the Coastal Bank. The proposed solution, he argued, would create nearly the same slope and stability as the neighboring properties while maintaining necessary protection for the perpendicular concrete wall and walkway. Ms. Thornbrugh expressed concern about recurring erosion due to increasing storm intensity and asked whether this approach would truly prevent future failures or simply serve as a temporary fix. Mr. Dibb reiterated that the failure stemmed from the previous, almost vertical, unengineered rock placement—not from the licensed concrete structure. The new riprap,he said, would be a properly engineered and much more durable design. Mr. Colombo then raised questions about the origin of the existing boulders, noting the agent's comments that their placement was undocumented. Mr. Dibb confirmed that the rocks had likely been placed decades ago,possibly at the same time as the licensed wall, but their exact origin was uncertain. He emphasized that all deteriorated materials would be removed and replaced with new,properly sized stone consistent with adjacent revetments. Mr. Colombo asked whether the new revetment would match the elevation of neighboring properties. Mr. Dibb confirmed it would, using a two-to-one slope matching the abutter's structure. The existing stones would 22