After breaking ground in the fall of 2014, the development known as USC Village, is proceeding nicely and set for completion this coming fall. The site lies within the City of Los Angeles at the northwest corner of Hoover Street and Jefferson Boulevard, about ½ mile west of the 110 Harbor Freeway and one mile south of I-10.
Phase I of the project will cover 11.7 acres and include 6 buildings. As part of Phase II, three additional buildings will be constructed on the remaining 3.3 acres, bringing the total building footage to 1.25 million square feet. With a price tag of $650 million project, the new facility will provide housing for 2,700 USC students and multiple commercial and retail spaces creating revenue for the local economy.
In accordance with the City of Los Angeles’s requirements, the team at kpff Consulting Engineers designed the site’s drainage improvements to a) reduce the impact on existing hydrological conditions and b) minimize, to the maximum extent practical, the impact to the local stormwater conveyance system. Proposed site improvements included a number of post-development best management practices (BMPs), which will meet both stormwater quantity and quality requirements.
Using a ¾-inch rainfall event, LA County’s LID Runoff Volume Calculator indicated a peak mitigated volume of 26,565 CF for Phase I. Preliminary field tests conducted at the site provided an infiltration rate of 100 inches per hour and groundwater was not encountered. With highly permeable beneath USC Village, the MaxWell IV was a perfect choice to meet the infiltration part of the design. CDS units were installed upstream of the each drywell to provide necessary pre-treatment.
Engineers divided Phase I into five separate drainage areas, each with its own stormwater management system designed to convey, store, and infiltrate the peak mitigated volume. For each drainage area, the cumulative volume drained through the drywell(s) within the first 3 hours was subtracted from the peak mitigated volume to determine if additional upstream storage was required. Only drainage areas B – E required additional upstream volume as shown in the table below.
Based on these calculations, every time it rains at least ¾ inch, approximately 200,000 gallons of stormwater is collected and recharged to the aquifer below. While this is great, it only represents a very small portion of the rain that falls on the USC Campus in an average year. According to the Western Regional Climate Center, USC receives an average of 14.5 inches of rainfall per year, which equates to about approximately 710,000 CF (5,315,000 gallons) of water across the 15 acre site.
A depiction of the drywell used at USC Village is shown on the reverse. In addition to these six MaxWells, Torrent has installed more than a dozen other drywells across the USC campus since 2008.