Crystallizing admixture seals stormwater storage structure

An unusually wet 2018 winter led to the official end of the worst drought in California’s history. But coastal Santa Monica, just west of Los Angeles, is maintaining water conservation targets for all residents, and undertaking several ambitious projects to advance supply self-sufficiency within the next few years. Efforts include wastewater recycling and construction of underground cisterns to capture storm runoff.

The repaved parking lot will bear on the 1.6-million-gallon cistern whose mid-summer construction was expedited with the use of precast methods.

Oldcastle Infrastructure fabricated the cistern elements for the Santa Monica contract with Penetron Admix-dosed concrete at its Fontana, Calif., operation. Olson Precast Co. of Rialto, Calif., delivered eight manholes project engineers incorporated in the Pier Drainage Basin plan.

“In light of climate change and anticipated impacts, which we know are longer, deeper, and more frequent droughts, and also reduced snowpack in the Sierras, our city council suggested these measures in 2012,” says Santa Monica Chief Sustainability Officer Dean Kubani.

A massive runoff storage structure known as the Pier Drainage Basin led the city’s Summer 2018 projects, he adds. The 1.6-million-gallon cistern will capture pollutant-laden runoff prior to treatment, followed by discharge to the Pacific Ocean. Harvested stormwater will be conveyed to the Santa Monica Urban Runoff Recycling Facility. At rates up to 500,000 gallons/day, it will treat flows—typically carrying litter, oil deposits and animal waste—that formerly went directly into Santa Monica Bay through storm drains.

Placed under a parking lot just north of the Santa Monica Pier, the Drainage Basin comprises a series of open precast concrete boxes positioned several feet underground to impound downtown area runoff. Penetron Admix was specified to make the concrete elements waterproof and resistant to the chemicals and pollutants often encountered in stormwater. The agent reacts with the water to form an insoluble network of crystals, which fill in cracks, pores and voids throughout the concrete matrix. The Pier Drainage Basin contractor realized schedule and labor savings on waterproofing aspects thanks to the performance characteristics of concrete bearing Penetron Admix.

“The main benefit of the project is cleaner water at the local beaches,” explains Penetron Group Director Christopher Chen. “In addition, the treated run-off water can now be used for non-potable uses, such as irrigation and flushing toilets, which will augment Santa Monica’s water resources.” — Penetron Group, East Setauket, N.Y., 631/941-9700;