KCI provided geotechnical, transportation, hydrological and structural engineering analysis, engineering evaluation and design services, as well as preparation of construction documents to aid in the stormwater pond and dam repairs located on Sweet Hours Way in Howard County, Maryland.
The existing corrugated metal pipe (CMP) riser and barrel were deemed irreparable based on inspections and Maryland Department of the Environment (MDE) Dam Safety Division requirements. The original proposed construction involved:
- Open cut excavations of the existing dam up to 30 feet deep to remove and replace the existing CMP riser and barrel
- Maintaining traffic by installing a temporary bridge structure spanning the 160 feet excavation
- Temporarily relocating existing storm drains and utility mains
- Constructing a new cast-in-place concrete riser structure and appurtenant facilities
- Installing a 66-inch diameter reinforced concrete spillway pipe (and drainage systems) and cast-in-place concrete endwalls
- Reconstructing the earthen embankment dam and roadway to original topography
- Removing the temporary bridge.
KCI geotechnical engineers performed subsurface explorations data collection and analysis of laboratory test results, and developed foundation recommendations. Our team also performed seepage analyses and provided filter diaphragm and drain outlet design for the embankment dam. A slope stability analyses was performed to develop earthwork recommendations including stable embankment slopes and construction sequence for the stormwater pond and dam repairs.
KCI was then re-directed to prepare design plans to decommission the 20-foot high roadway embankment classified as a dam by MDE, by removing the existing stormwater pond, existing riser, and outlet works and construct a new roadway culvert through Sweet Hours Way. The new roadway crossing was designed as a roadway culvert according to MDE Dam Safety standards, thus decommissioning the embankment as a dam. Stream stabilization measures were designed upstream of the culvert to transition the stream through the existing pond (to be removed) to the culvert and downstream of the culvert to stabilize the existing channel from the significant increase in discharge due to the loss of attenuation from the existing pond.
The project was performed utilizing applicable data and work products from KCI’s previous Tasks for the Sweet Hours project site. Items include previous survey, site investigation, geotechnical, environmental, structural analysis, and hydrologic and hydraulic engineering work.
It is anticipated that this project will require regulatory approvals/permits from Howard County, Howard Soil Conservation District (HSCD) for storm water, MDE Dam Safety Division, MDE Nontidal Wetlands and Waterways and U.S. Army Corps of Engineers as described herein.