bg真人app is supporting Louisville MSD’s Consent Decree program by providing the geotechnical field exploration and construction observation for a 20-million-gallon, 449-FT x 207-FT x 49-FT underground CSO basin beneath Shawnee Park in Louisville, 肯塔基州. 在潮湿天气期间, un治疗 wastewater and stormwater are captured by conveyance pipes and stored in the basin rather than flowing into the 俄亥俄州 River. 等雨停了, and system capacity is available, the mixture of wastewater and stormwater will be pumped back into the sewer system. 在这一点上, the water is conveyed to a water quality treatment center, 治疗, 然后回到俄亥俄河. 当完成, the project will be largely invisible to the public and will enhance not only the water quality of the 俄亥俄州 River, but also the quality of one of Louisville’s premiere parks.
结构, 包括一口湿井, 泵站, 业务建设, and three CSO diversion structures, were designed on a mat foundation with columns supporting the roof slab. Auger-cast piles were utilized to resist uplift forces. Steel sheet pile walls with tie-back anchors on multiple levels were utilized to provide both temporary and permanent excavation support. Cast in place concrete walls formed the sidewalls of the structure and the annular space between the sheet pile walls and sidewalls were backfilled with sand from the basin excavation.
bg真人app's geotechnical field exploration consisted of seven soil test borings, two with rock core extending 30 feet into bedrock each. Each of the soil test borings were drilled to the depth of auger refusal or to a predetermined boring termination depth. In addition, two piezometers were installed to depths of 65 feet. Laboratory testing consisted of unconfined compressive strength testing, gran-size分析, and hydraulic conductivity testing.
Several geotechnical analyses were performed for this project. A seepage analysis was performed to determine the minimum depth necessary to prevent groundwater infiltration through the subgrade into the basin. For the portion of the wall below the sheet pile wall, the lateral earth pressure imparted by the soil between the walls was calculated utilizing the theory proposed by Spangler and Handy for fascia walls adjacent to a stable rock face. The lateral pressure on the fascia wall is a function of the weight of the soil between the walls and the coefficient of friction between the soil and two walls. For the sheet pile wall a Rankine earth pressure analysis was performed assuming active conditions. For the basin and 泵站 walls “at rest” conditions were assumed since those walls were not free to rotate due to the restraint at the top of the wall. Bearing capacity values were derived for the sands beneath the basin and the near surface material for the various structures. Buoyancy forces were calculated for the basin assuming it was completely submerged and void of water.
Various submittals were presented to bg真人app for review during and subsequent to construction. Sheet pile wall designs were submitted and reviewed by bg真人app and other members of the design team. When found inadequate, additional support was added to account for discrepancies. Other submittals include modifications to the backfill between the sheeting and basin wall, compaction methods (flushing and jetting vs vibratory compaction), modification to the bearing capacity at the pipe support, 螺旋桩安装, updating proctor and classification data, 以及其他的提交.
During construction, sand washed through the sheet pile walls creating voids outside of the walls. bg真人app returned to the site and drilled borings near the wet well, 泵站 and 业务建设 to determine the extent and location of voids located beneath the structures. Significant void space was encountered and the design team elected to fill the voids with grout. bg真人app performed several additional borings grouting the borings using a tremie method to fill the void space with grout.