Hydrology and Drainage

The site receives stormwater runoff from neighboring impervious surfaces. Stormwater runoff contributes to pooling as well as concerns over water quality, which should be addressed as part of promoting wetland habitat on site.

Outcrops of shallow bedrock create areas where the water table is close to the surface, resulting in seeps. Flow from these as well as rainwater falling on the site is channeled by topography into several drainages that flow downhill across the site. None of these drainages are classified as perennial streams; they typically flow during spring when groundwater levels are high, but are often dry the rest of the year. Runoff produced on the property either infiltrates into the ground or flows via these drainages into the Damariscotta River.

Erosion in drainage

Exposed mineral soil and incision below the level of the surrounding fields— becoming deeper as they approach the river—indicates that these drainages may also carry volumes of water during and after heavy storms significant enough to cause erosion in the channels.

Concentrated runoff from road

A section of Main Street just north of the Coastal Rivers property cuts through a slight rise such that the road sits slightly below ground level on either side. As a result, stormwater falling on the road and parts of the neighboring parking lots is channeled down the road to a catchbasin across the street from the site. A culvert from the catchbasin discharges this runoff into the pad area on the site.

C

Sediment deposition Overall direction of drainage

Hydric soil

A soil sample taken from one of the drainages near the gravel path shows redoximorphic features characteristic of frequently saturated soil. These features are one piece of evidence used to define wetland areas.

F

A

F G

D E

C

B

Culvert D

Sinkhole

Sinkholes and underground channels occur in the fields below the barn and near the solar array.

Water pooling in orchard

E

Drainage path Drainage area (catchment) Impervious area draining to culvert

Water pooling at trailhead parking

Stormwater runoff contains many potential contaminants such as sediment, heavy metals, and hydrocarbons as well as road salt and debris. This material accumulates in the catchbasin and culvert, which must be periodically cleaned out. Between cleanouts, however, these materials can overflow and be deposited onto the Coastal Rivers property. This is a major issue since this area is one of the most visible and intensively used parts of the site. Water ponding and unsightly debris piles interfere with public use and enjoyment of the area and can negatively impact vegetation and water quality downstream. Other areas where water pooling can be problematic include near the head of the gravel path and in the orchard area. These areas receive water flow from the Round Top Ice Cream parking lot and western side of Main Street (in the case of the path area) and from part of the driveway and farmhouse gutters and footing drains (orchard). Wet areas can interfere with visitor activities and lead to accelerated erosion and damage along trails and in low spots.