Port of Long Beach Stormwater Harvesting Feasibility Study - Improving Water Quality and Enhancing Water Supply

The Port of Long Beach (Port) is the second-busiest seaport in the United States and committed to improving the environment. Capturing and using stormwater can offset potable water demand, result in reduction of pollutant discharges, and enhance regional drought resiliency. Therefore, the Port and its consultant, Stantec, conducted the Stormwater Harvesting Study to prioritize stormwater harvesting options for the Port. The following three scenarios for stormwater capture were examined: Onsite use, wherein stormwater would be captured, diverted, treated to meet Department of Health standards to use as an alternative water supply, and then provided to select Port tenants for use, with excess water being diverted to sanitary sewers or outfalls. Diversion to the sanitary sewer, wherein stormwater would be captured and diverted to the sanitary sewer for treatment and use off-site. Diversion to Long Beach Municipal Urban Stormwater Treatment (LB-MUST), wherein stormwater would be captured and diverted to the LB-MUST facility for treatment and use by the City of Long Beach. To prioritize locations for stormwater harvesting and onsite use, a pass/fail screening was applied to the Port's drainage basins, followed by a weighted screening criteria and ranking value. Top scoring drainage basins were linked to specific tenants within the Port to determine the final scenarios. A general concept for these projects is shown in Figure 1. Twenty-two Port-owned stormwater pump stations were analyzed for diversion to the sanitary sewer. Locations were prioritized based on the pumping capacity, and screened if located upstream of a drainage basin, in a crowded area, or not located near a viable sewer for discharge. A general concept for these projects is shown in Figure 2. Diversion to LB-MUST considered the available treatment capacity at the LB-MUST facility and the design capture volumes of drainage basins within the Port's Pier B. Two alternatives, a below ground tank and a detention basin, were considered to store the diverted stormwater within the City of Long Beach prior to diversion to LB-MUST. A general concept for these projects is shown in Figure 3. A Triple Bottom Line Cost Benefit Analysis was performed to prioritize the projects. This analysis integrates the broader social and environmental perspectives into decision making, and enables project proponents to objectively justify a project. A ranking of all projects is in Table 1.