Columbia Gateway Stormwater Management Pond Dam

Client: Howard County Department of Public Works

Location: Columbia, Maryland

Services: Geotechnical Engineering

The existing stormwater management pond in the Columbia Gateway Office includes a 30-foot high dam at the eastern end of the pond. The dam includes a 10-foot high, 120-foot long reinforced concrete barrel pipe spillway outfall. The spillway has a riser and two anti-seep colors. The dam is classified as one of the County’s high hazard dams.

KCI was contracted to perform an inspection of the dam, conduct a preliminary geotechnical exploration study, and prepare remedial design plans. Following the inspection, engineers identified and developed recommendations and cost estimates to address problems at the dam, which was experiencing dewatering issues at the downstream wingwalls and remedial grouting of the existing reinforced concrete spillway pipe joints.

Engineers identified the presence of significant reddish/brown staining due to potential groundwater seepage and/or soil inflow at several of the 17 joints inside the concrete spillway pipe. KCI also observed wet soil conditions at the wingwall outfall areas with continuous water seepage over the wingwalls and significant reddish-brown staining on the face of the headwalls and wingwalls.

Remedial design were prepared for a wingwall drainage system and grouting repairs to the concrete pipe spillway. KCI obtained maintenance and repair permits for the dam and will provide construction monitoring and oversight during construction.

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