Lows Lake Dam - Water Control an Cofferdam Bypass Plans
Client: DASNY, NYS DEC | Location: Town of Colton, St. Lawrence County, NY | Completion Date: 2017 | Services Provided: Civil Engineering, Land Surveying
Aubertine and Currier, PLLC provided Engineering and Construction Surveying services associated with the upgrades and repairs to the Lows Lake Dam Reconstruction Project. The construction project included improvements to Lows Lake Dam required for NYSDEC Dam Safety Regulation compliance and extending the service life of the structure. The improvements will be achieved by adding a reinforced concrete overlay to the existing concrete overflow spillway and a pile-supported concrete toe block at the downstream toe of the existing dam. Two rows of 7" diameter micropiles will provide foundation support for the toe block. The new concrete toe block will be constructed above the existing concrete apron, such that no excavation in the stream bed below the dam will be required. A pre-cast panel wall will be added to the downstream side of the non-overflow section. Steel tie rods will be drilled into the existing non-overflow structure to tie the precast panels to the existing dam. Control of water will require design and installation of a temporary cofferdam to allow dewatering of the upstream face of the dam, while maintaining the lake water level at normal pool. Bypass and conservation flow will be provided to the downstream channel by opening the existing low level outlet through the dam until spillway section work is complete.
A&C was contracted by Kingsbury Companies to analyze, design and prepare Water Control plans necessary for cofferdam construction and flow bypass of the dam’s spillway and work area. Hydrologic analysis of the 35 square mile watershed was prepared, which included the Five Ponds Wilderness area of the Adirondack Mountains. Base flow comparison data was analyzed for the downstream Raquette River stream gauge, at Tupper Lake. Hydrologic and hydraulic modeling of the 35 square mile watershed, existing 24’ concrete weir spillway, and 36” dia. low level drain were completed for existing conditions and construction bypass conditions. Hydraulic calculations were completed for sizing of the contractor’s proposed sheet pile cofferdam, primary and secondary bypass weirs, and extension of the existing 36” Lows Lake Dam drain pipe for bypass and dewatering during construction.
Survey services included field topographic survey and mapping of the existing dam and spillway, baseline layout, and As-Built survey, and mapping.