Hull-02B

Hull, Hull Bay

42.278534, -70.877467

Dimensions: 6ft diameter, 5ft height
Condition: Fair
Comments: There were no apparant structural issues observed at the concrete box culvert; however, the headwalls on both the upstream and downstream end of the culvert were in poor condition. Significant spalling and exposed rebar was observed on both the upstream and downstream headwalls. Further, the access rungs leading from the top of the headwall down to the tide gate were corroded.

Comprehensive field assessment conducted in 2024

Upstream Invasive Species: Yes
Downstream Invasive Species: No
Invasive Species Notes: Phragmites limited to upland fringe.
Additional Comments (2024): Marsh appears to be in good condition with a healthy mix of low marsh and high marsh species. Tide gate is mostly closed but appears to be allowing adequate tidal exchange.

Legacy data from previous surveys and documentation

Invasive Species: Yes
Restoration Status: Proposed
Invasive Comments: Upstream marsh appeared to be relatively healthy with a mixture of low and high marsh species. Phragmites were observed at the fringes.
Restoration Comments: Previous water level logging was performed determine the relative extent of upstream restriction. Low lying properties including a cellular tower and guy wires were observed within and around the impoundment.

General Comments: Site was easily accessible by walking northwards along a paved berm for approximately 500 feet off of Nantasket Road. Next steps: Recommend that a structural and operational assessment of the tide gates and headwall be performed per below comments. Obtain preliminary water level data previously collected at the site.
Operation Plan: No
Operation Comments: Wooden flap gate is chained open at mouth of headwall. It appears that the flap gate is lowered during anticipated storm surge events for additional protection of upstream area (i.e., emergency closure).
Gate Comments: Tide gate is a large wooden flap gate chained in place at the mouth of the culvert. Tide gate appeared to be in good condition. Note there was also a metal sluice gate located upstream of the flap gate (See Hull-02A)

Elevation Comments: Staining was apparent on the upstream (U/S) and downstream (D/S) ends of the headwall (HW) so approximate extent of U/S and D/S tidal influence was able to be assessed in addition to tide gate (TG) invert elevations. The below lists measuredowns taken with a surveyors rod and corresponding top of headwall LiDAR elevations (NAVD88 datum). 1) TG Inv (in this case measured to invert of D/S culvert): Top of HW El (U/S) = 13.14’; Inv Measuredown = 16.25’; TG Inv = 13.14 – 16.25 = -3.11’ 2) Upstream Tidal Influence: Top of headwall LiDAR Elevation = 5.61’; Staining Measuredown = 2.52’; U/S Tidal influence = 3.69 – 2.52 = 1.17’. 3) Downstream Tidal Influence: Top of headwall LiDAR elevation = 13.14’; Staining Measuredown = 11.55’; D/S Tidal Influence = 13.14’ – 11.55’ = 1.59’ Note: LiDAR was inconsistent on both upstream and downstream headwalls. In order to obtain values, averaged two representative values for each side. Downstream = 12.66’ & 13.62’ = 13.14; Upstream = 5.64’ & 1.74’ = 3.69’