Reservoir Seismic Evaluation, North Perry Avenue Water District, Bremerton, WA
North Perry contracted with BHC to perform a seismic evaluation on three reservoirs: the Olympus 1 MG, Sunset 2 MG, and Sunset 0.5 MG reservoirs. All three reservoirs are welded steel, ground-supported reservoirs, and the two Sunset reservoirs are standpipes (the tank height is larger than the diameter).
The evaluations compared the existing tanks to the seismic criteria in the 2012 International Building Code (IBC), American Society of Civil Engineers (ASCE) Standard 7-10, Minimum Design Loads for Buildings and Other Structures, and American Water Works Association (AWWA) Standard D100-06 Welded Steel Tanks for Water Storage.
The seismic analysis included evaluation of sloshing wave height, impulsive and convective fluid masses, and periods using AWWA D-100 methodology; base shear and maximum overturning moments; shell stresses and foundation uplift/download; and anchor forces for anchored tanks and annular plate plate capacity for unanchored tanks. Hydraulic modeling was performed to determine whether the tanks met the definition for "essential facilities."
BHC prepared a technical memo that described the reservoirs and field conditions, indentified evaluation assumptions and factors, presented the results of the evaluation, and recommended upgrades. Each reservoir required upgrades to meet the current seismic code. BHC also prepared opinions of probable construction costs (OPCCs) for the recommended upgrades, and estimated costs of repair/replacement for each reservoir assuming the design earthquake.
Everson Wastewater Treatment Plant Facilities Improvements, City of Everson, WA
BHC provided planing and final design of WWTP improvements. These facilities include a new process control and laboratory building, influent pump station upgrades, modifications to the oxidation ditch aeration system, the addition of biological selector facilities, clarifier upgrades, and new sludge dewatering equipment. The new 2,500 square foot control and laboratory building includes office space, laboratory, bathrooms, and storage and shop space.
BHC is responsible for building structural design, equipment selection, piping layout, project management, development of PS&E/bid documents, and engineering services during construction.
Summary Structural Report, Northshore Utility District, Bothell, WA
The District identified a number of existing water and sewer pipeline facilities within its system that have a potential high risk of damage or failure resulting from various causes (e.g. - earthquake or structural overload). Many of these facilities include a bridge, stream, or steep slope crossing. BHC inspected and prepared a report on existing water and sewer pipeline conditions and retrofits for crossings at the Sammamish Slough and tow other water crossings.
Water Tanks #4 and #5 Safety and Seismic Improvements and Repainting, Covington Water District, WA
BHC was responsible for a condition survey and structural evaluation of an existing 4 MG water reservoir (Tank #4) and preparation of plans and specificaitons for repainting another 4 MG water storage tank (Tank #5) for the Covington Water District. Tank #4 is a welded-steel reservoir constructed in 1976, and the structural evaluation concluded that the tank was under-designed for current seismi codes and that a retrofit was not economical. Tank #5 is a 4 MG steel water reservoir witha sidewall height of approximately 30 feet. Work included services during construction on Tank #5.
Wastewter Treatment Plant Air Blower Building, Washington Beef, Toppenish, WA
BHC was responsible for the structural design of a reinforced concrete and masonry air blower building with combined retaining wall. The project also inlcuded design of a single story building filter and design of a 1 MG reinforced contrete SBR tank, partially buried.