This project includes replacement of 35 pressure reducing stations within the City of Bellevue service area. The stations will be replaced using 5 separate projects over a period of two and a half years. BHC was responsible for project management, surveying, design, development of plans and specifications, opinions of probable cost, and bidding services. The projects include new underground vaults, large and small pressure reducing valves, low zone relief valves, water quality monitoring equipment in nine of the stations, cathodic protection, reconstruction of roadways and sidewalks, landscaping, and permitting assistance.

 

The District hired BHC to perform a comprehensive update of the distribution system hydraulic model using InfoWater software, by MWHSoft. This work included importing the model from H2O Net; verifying/revising existing model settings; assessing the accuracy and completeness of the existing piping network; globally updating node elevations using LIDAR-based topo data; assessing the distribution of system demands; field hydrant flow testing and system wide calibration of the updated model.

 

As part of the South Lewis County Subarea Plan preparation, BHC evaluated the availability of water to serve the projected development.  These included existing urban growth areas for the cities of Toledo, Vader and Winlock plus several new UGA’s proposed in unincorporated Lewis County.  We assembled available data to document existing water rights, projected future water demands, evaluated possible water conservation activities, considered potential for water reuse, and identified future water rights that may become available under instream flow rules.

 

BHC was responsible for final design and construction observation services for additions and improvements to Shoreline Water District’s water system along NE Perkins Way and nearby streets. Improvements included approximately 3,700 feet of 12-inch water main, 750 feet of 8-inch water main, valves, connections to existing mains, hydrants and services, and other associated appurtenances. The project also included pavement patching of the existing roadway and other right-of-way restoration.

 

BHC is responsible for the design, permitting, and services during construction of approximately 2,700 feet of 20-inch waterline connecting the intersection of 180th Ave NE and Avondale Road NE to a new PRV station at the Millennium Corporate Park along Union Hill Road.  The waterline will be installed under Bear Creek and three agricultural ditches by means of microtunneling and other trenchless technologies.  Various pipe materials were considered for the design, including HDPE, Ductile Iron and Fusible PVC.  Because a significant portion of the pipeline alignment will be underneath a future wetland, it is imperative that the pipeline construction does not drain the wetland or prevent growth of wetland plants.  The site is archaeologically sensitive, and therefore, has undergone archaeological studies to determine means and methods of observation during construction.

 

BHC developed the 2008 Water System Plan for the Highline Water District as well as providing project coordination and management. Work included updating the computer model (AutoCAD version of H2ONet-based) to include recent system improvements. BHC staff evaluated planning data and water demands, reviewed and analyzed the current system, conducted a water resource analysis to identify appropriate additional conservation measures, and documented an expanded Conservation Program that addresses requirements from the Municipal Water Law and the Water Use Efficiency Rule. BHC was responsible for the preparation of an updated O & M manual, the development of a Capital Improvement Program (CIP) evaluation and approval process, and a detailed Asset Management Plan. A training program for district staff and a public involvement program was also developed and conducted by BHC.

 

BHC is assisting PUD staff with updating the water system plans for several of their systems.  We will complete an analysis of existing facilities, evaluate future needs, and develop the capital improvement program for the Pirate’s Cove Water System Plan Update by August 2010.  Similar analyzes of the Lake Arrowhead and Lakewood Heights water system plan updates.  We have completed the initial training for PUD staff in hydraulic modeling and will provide further training assistance as needed by the PUD. 

 

BHC updated the District’s hydraulic model using InfoWater software. A series of hydrant flow tests were identified and the model was calibrated to resulting field data. An assessment of system demand distribution and projections was also performed. A range of modeling related tasks were performed, including static and extended period simulation (EPS) analyses; pressure rezone analyses; system-wide fire flow analyses; water age analyses; identification of improvement alternatives and development of a capital improvement program. Collectively, the modeling analyses resulted in a substantial monetary savings to the District’s Capital Improvement Program.

 

BHC completed a condition assessment and seismic structural evaluation for two, welded steel reservoirs for the Covington Water District. The reservoirs were 2MG and 4MG ground storage tanks constructed in 1971 and 1980, respectively. Scope of work included topographic survey and geotechnical investigations, as-built drawings for the 4MG tank, external and internal inspection of coatings, welds, and structural condition, and underwater inspection and tank cleaning. Part of the work also included design and fabrication/installation of railing and tieoff clips on the roofs to improve safety during inspection.

 

Seismic evaluation included consideration of roof sloshing wave contact effects. Settlement analysis included sine curve fitting of ringwall elevations to compute foundation rotation.