Cohasset-04

Cohasset, James Brook

42.237146, -70.801229

Dimensions: 2.5ft diameter
Condition: Good
Comments: Culvert was CMP and appeared to be in good condition. Headwall was constructed of masonry block and also appeared to be in good condition. Downstream portion of culvert was overgrown and appeared to be a stormwater ditch rather than a permanent channel.

Legacy data from previous surveys and documentation

Invasive Species: No
Restoration Status: Not Applicable
Invasive Comments: Resident indicated that upstream impoundment used to be a pond; however, indicated that Town of Cohasset drains it for winter ice skating. Mowed cattails were observed throughout the upstream impoundment.

General Comments: Site was located to the north of the intersection between Cushing Road and Oak Street directly to the south of a railroad berm and was easily accessible.
Operation Plan: No
Operation Comments: A resident indicated that the Town of Cohasett drains the impoundment and turns it into a skating rink in the winter. It did not appear that there was any tidal influence at the site and appeared that the impoundent receives stormwater runoff from the surrounding neighborhood and conveys it downstream over the stop logs.
Gate Comments: Control structure consisted of a concrete weir with wooden stop logs. The stop logs were set to a height of 2.5', but could be adjusted up to 3.8'. The weir and stop logs appeared to be in good condition.

Elevation Comments: Extent of tidal influence and invert elevation was not assessed. There did not appear to be any tidal influence at this site (i.e., it was too far upstream); however, the invert elevation was assessed. The below lists the measuredown taken with a surveyors rod and corresponding top of headwall LiDAR elevation (NAVD88 datum). 1) TG Inv (in this case measured to bottom of stop log): Top of HW El (D/S) = 8.12’; Inv Measuredown = 5.00’; TG Inv = 8.12’ – 5.00’ = 3.12’