Project Overview
Contaminated ash and burn materials from a former Naval air station at Alameda Point in San Francisco Bay were bulldozed into the bay and later buried under silt in the 1940s and ’50s. Trace radioactive elements found in the ash required special cleanup, but relocation and treatment costs far exceeded the budget. After multiple unsatisfactory design attempts from others, the client approached PND to develop an OPEN CELL SHEET PILE™ (OCSP™) waste isolation bulkhead (WIB) concept which fulfilled the requirements for leaving the materials on site while meeting tight budget and time constraints.
PND provided design and construction support services for the WIB, an approximately 1,240-foot OCSP Vertical Confined Disposal Facility (VCDF) located on the western shoreline of the former Navy base and federally designated Superfund site. The OCSP VCDF is a low-maintenance bulkhead, eliminating seepage through its robust containment structure and reducing and/or eliminating contaminate migration under the containment structure. The U.S. Army Corps of Engineers reviewed the award-winning marine infrastructure and found it effective. PND’s OCSP WIB successfully blocks waste chemicals from entering San Francisco Bay, costing less than half of what it would’ve taken to remove the waste from beneath the shoreline. The area is now suitable for passive recreational use.
Our Role
- Coastal Engineering: implemented an OCSP™ system to effectively contain waste materials from seeping into the bay
- Hydrology & Hydraulics: assessed sheet pile permeability, evaluating hydraulics and providing recommendations to inform groundwater flow numerical model
- Structural Engineering: preliminary design included liquefaction/lateral spreading analysis and cathodic protection
- Construction Support: observed fabrication and construction to ensure work safety and quality
Supporting Shoreline Protection from Start to Finish
PND’s preliminary design included a liquefaction and lateral spreading analysis, cathodic protection design, cost estimates for materials and construction, and engineering support for preparing the feasibility study report. We assessed sheet-pile permeability, which evaluated the hydraulics and provided recommendations that helped inform the groundwater flow numerical model. PND prepared a design document report, coating specifications, and final design; observed fabrication and on-site construction of the OCSP™ WIB; reviewed contractor submittals; and provided engineering support during construction.
“PND has proven to be a dedicated team partner and a true steward of the environment. I believe that as word spreads, more environmental projects will see the benefits of the OPEN CELL SHEET PILE™ waste isolation barrier for containing wastes in place as an alternative to risky excavation, transportation, and disposal efforts.”
Upon the project’s completion in 2015, the area became suitable for passive recreational use by the community, and the U.S. Navy added a new 2.25-acre native grasslands and wetlands at Alameda Point’s northwest shoreline corner.
Cost Savings
of PND’s OCSP™ WIB compared to removing the waste
Feet of OCSP WIB
now protecting San Francisco Bay
