Liberty Station East Hotel Offsite Improvements

PROJECT: Liberty Station East Hotel Offsite Improvements
LOCATION: Downtown San Diego
PRODUCTS: Modular Wetlands’ MWS Linear
COMPANY: Modular Wetlands

Introduction

Liberty Station is a mixed-use development in San Diego, California on the site of the former 360-acre Naval Training Center San Diego.¹ The area supports 650 rooms in three separate hotels, a 3,800-square-foot restaurant space, parking spaces and Kincaid Road improvements. It has a waterfront location, on a boat channel off of San Diego Bay, just west of the San Diego Airport and a few miles north of Downtown San Diego. The hotel itself reflects a contemporary Spanish Revival style architecture of existing historic buildings in Liberty Station that will add a vibrant style to the San Diego landscape.² The project was appointed by the City of San Diego General Plan.

The Challenge

McMillin NTC, LLC commissioned a team of engineers at Rick Engineering firm and TC Construction to evaluate a number of stormwater treatment solutions for the new development. Like most construction projects in urban areas near the coast line, the existing discharge point from this site is fairly shallow.  In turn, the shallow discharge point established the rest of the site’s stormwater design.

The catch basins on the project were in sump conditions with flow coming from two directions. Four sump style catch basins were needed for treatment. This situation would typically require eight bioretention basins, one on each side of the catch basins.

After an in-depth engineering and cost analysis by the Modular Wetlands team, it was determined that using the DVERT tm water quality diversion weir in conjunction with two Modular Wetlands’ MWS Linear systems would fulfill requirements for stormwater runoff treatment.

The Solution                                                      

The MWS Linear was the most feasible option to meet the challenges of the project. First, it is the only stormwater system with the design capability to reach as shallow as 1.5 feet; enough to accommodate the existing catch basin. Second, the MWS Linear is the only system that can utilize DVERT troughs.  The DVERT trough works similar to a rain gutter.  It captures the low flows and channels them over to a connecting pipe exiting out the wall of the inlet and leading to the MWS Linear.

The Result

The MWS Linear provides the new development with a heightened treatment level for debris, sediments, TSS, metals and several types of nutrients (detailed pollutants removals can be found in the table below). The MWS Linear is the only cost-effective stormwater BMP available to achieve 0.13 cfs treatment capacity in a minimal footprint with minimal fall requirements. Liberty Station has been able to effectively address stormwater runoff discharge and meet original expectations.

REFERENCES
¹[https://en.wikipedia.org/wiki/Liberty_Station,_San_Diego]
²[http://www.sandiego.gov/planning-commission/pdf/pcreports/2013/pc13032-1of2.pdf]

Performance

Pollutant Removal Efficiency
Total Suspended Solids 85%
Total Phosphorus 64%
Ortho Phosphorus 67%
Nitrogen 45%
Dissolved Zinc 66%
Dissolved Copper 38%
Total Zinc 69%
Total Copper 50%
Motor Oil 95%