Carroll Land Services, Inc.

Scope Of Work

The existing recreational wet pond was expanded to handle stormwater management from the surrounding drainage area.  The facility lies in a valley with streams on three of its four sides and receives approximately 250 acres of urban drainage.

The goal for this project was to capture this water and divert it into the retrofitted regional stormwater management facility.  The stormwater is captured in manholes at or near the ends of the existing culverts that go under Maryland Route 140 and the exit ramp from Maryland Route 140 to Maryland Route 97. PVC pipes are proposed in these manholes to allow the base flow from the culvert to continue into the receiving waters (streams) in which the existing culverts outfall, which minimizes the impacts to the existing streams.  The design diverts the remaining water into the retrofitted regional stormwater management facility.  This facility provides water quality, channel protection, and flood management for the 250-acre contributing drainage area.  The existing facility was re-graded, which increased the volume, and the top of the embankment was raised from about 3′.  3:1 slopes were used on the downstream embankment and 6:1 slopes or greater were used on the pond face in the design of this facility.  A safety bench was added around the border of the pond, as required by MD-378 regulations.  A forty-foot emergency spillway and a concrete riser were added that discharge directly into the 100-year FEMA floodplain.

In order to accommodate the required stormwater management volume, the existing facility nearly doubled in size.  This facility is also in a park and, due to this, additional parking was added, as well as a bridge across the pond, a fishing pier (in place of the island being removed), and an ADA accessible walking path around the facility.

This site offered many challenges to the design team.  There were wetlands, streams, forests and an existing pond on-site that were all being disturbed to some extent.  CLSI and the Carroll County Government met with MDE and the Army Corp of Engineers on-site and agreed on a pond layout that would offer the least amount of disturbance to the existing sensitive environmental areas.  A Non-tidal Wetlands and Waterways permit was applied for and received.  Dam Safety review was required for the approval of this facility.  This facility also captured Maryland State Highway (SHA) impervious surfaces.