Mixed-Use
The 15th & Webster project demolishes two existing buildings at 1500 and 1510 Webster Street in Oakland and replaces them with a 19-story mixed-use tower with ground-floor retail and office space and 182 residential units above. The two parcels were merged into a single site totaling approximately 14,231 SF.
Calichi’s scope covered stormwater and drainage design, dry utility consulting, and sewer capacity coordination. The project triggered Provision C.3 of the Municipal Regional Stormwater Permit (MRP), requiring treatment of 100% of the site’s impervious area under the City of Oakland’s Special Project “A” designation. We designed a basement-level media filter system using a Contech Stormfilter unit with phosphorb cartridge filters to capture and treat runoff from the roof and ground-floor common areas. A new 12-inch storm drain lateral carries the treated outflow to the existing 36-inch public main in Webster Street via a proposed manhole.
With the building footprint covering 90% of the site, there’s almost no room for surface-level BMPs. Reaching Oakland’s 25% peak discharge reduction goal was cost-prohibitive at that density. The media filter combined with permeable pavers at the building perimeter delivers a 9% post-peak reduction below pre-development conditions, satisfying the permit within the constraints of a fully built-out urban lot. Sewer capacity was verified through a flow monitoring study, which Calichi coordinated with a specialty subconsultant and submitted to the City.