Marina Area Storm Drain Project - City of Benicia, CA
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The Marina Area Storm Drain Project is located along the Carquinez Strait in the southern portion of the City of Benicia. This area consists primarily of residential development with commercial and retail along 1st Street and Marina Yacht Harbor. The project area was prone to frequent flooding and in 1997, during the construction of a new residential development, it came to the City’s attention the existing 66-inch storm drain system on East Second Street was deteriorated and required rehabilitation or replacement.
The City’s hydrologist completed an extensive study of the area and the selected alternative required the replacement of the existing storm drain system with a dry weather pump station in a parking lot near the northwest corner of the marina. The pump station would divert dry weather flows to a discharge point on East Second Street. Wet weather flows exceeding the 0.62 cfs low flow pumping capacity would be discharged into the marina through a submerged twin 48-inch outfall pipe. The City prepared an Environmental Impact Report (EIR) for the selected alternative.
The City of Benicia entered into a contract with Pakpour Consulting Group to design a project consistent with the approved EIR. The project involved removal of the interim pump station and construction of a new permanent pump station. The new pump station conveys storm water into the marina through twin 48-inch RCP discharge pipes. A low flow bypass was also constructed involving two 4-inch storm drain lines connecting to a 6-inch force main along East 2nd Street. The project also included installation of storm water treatment units upstream of the pump station to remove oil and sediment along with other best management practices.
Pakpour Consulting Group faced several major obstacles, including an accelerated schedule and the aesthetics of the outfall structure. To meet the schedule requirements of the project the design team assembled a seven member sub-consultant team. The landscape subconsultant employed an approach of using existing rock rip-rap and some artificial rocks to create shadows which “hid” the outfall structure. The design team coordinated extensively with all the stakeholders in the project to ensure no aspects of the project were visible once the construction was complete.
