Orange County Branch Newsletter

June 2011

OC Firm Spotlight

The Wet and Wild Side of Water Engineering: PACE

Imagine creating new technology for the world’s largest manmade surfable wave, understanding complex hydraulics in a flood control channel through experiments in an actual scaled model, and developing new water/air purification and recycling technologies for the Biosphere enclosed ecosystem experimentation station. What do all of these have in common? A specialized focus in research-based environmental water resource engineering solutions. This is what Pacific Advanced Civil Engineering (PACE), founded and headquartered in Orange County, is all about.

PACE was formed 24 years ago, after operating as the engineering division of Pacific Aquascape, a water feature design-build company.  The company formed after recognizing a need for advanced water treatment, water recycling and flood control solutions and knowing this could be achieved with value-adding, multi-objective systems. PACE focuses in three main water resource areas, Stormwater Management, Environmental Water (specializing in water and wastewater treatment and infrastructure), and Recreational Water (specializing in manmade lakes, water features, pools and spas).  Today, the company has offices in Orange County, Phoenix and internationally in China, Russia and Egypt.

With its foundation in Orange County, a number of advanced water resource projects are located right in our backyards. Talbert Lakes, located in the City of Huntington Beach, is a unique urban runoff water quality improvement project that is designed to divert up to three million gallons per day of nuisance dry weather runoff from the East Garden Grove Wintersburg  Channel to a constructed wetland treatment train system and polishing lake located in the City’s Central Park. With design plans recently completed and construction pending, this project will prevent highly polluted runoff (collected within a 22-square mile area) from discharging into Huntington Harbor and the Bolsa Chica Wetlands, while enhancing Central Park aesthetically, environmentally and recreationally.  The project treats and reclaims approximately 1,300 acre-feet of a previously unused water source.

One of our recent hydraulic research endeavors, a 15:1 scale physical model of a 1,000 foot reach of the East Garden Grove Wintersburg Channel located at the I-405 freeway, was developed for OC Public Works.  It was developed to allow evaluation of various configurations of channel modifications to improve conveyance capacity. The study reach of the channel is influenced by a unique geometric configuration, multiple confluences and complex culvert crossings, making it extremely difficult to analyze using conventional computer modeling alone. A 150-foot long model constructed of wood with four horizontal axial flow pumps and electromagnetic flow metering allowed for numerous configurations to be evaluated and demonstrated hydraulic conditions not identified through computer modeling.

Some may remember an outbreak of rotten egg smell in southern Orange County in the fall of 2009. After a large and sudden temperature shift from warm to cold, the Upper Oso Reservoir operated by Santa Margarita Water District, experienced a turn-over event releasing hydrogen sulfide emissions that were previously trapped in the lower layers of the reservoir. Based on a strong understanding of lake systems, nutrient loading, limnology, biological and mechanical processes, and specialization in wastewater treatment and recycled water storage and distribution, emergency services were first provided including a diagnosis and short-term oxidation solution that was designed and constructed within a few days and operated for one month. Following the emergency solution, a detailed study including computer modeling, monitoring and water testing was conducted to determine the cause of the odor outbreak.  The design for a permanent system to prevent future outbreaks from occurring was completed. A permanent deep water oxygenation system was determined to provide the most benefit to the reservoir and in 2010 a 2,000 lb/day oxygen injection system was selected, modeled, designed and constructed. With the system operating so far in 2011, the reservoir appears to have the best water quality on record.

It is vital to take a step back and apply research that goes beyond what the standard engineering textbooks have to offer.  Applying natural processes wherever possible, especially in light of heightened environmental awareness, surrounds our practice. PACE has made out-of-the-box thinking a norm in its culture as it strives to achieve both engineering function and environmental enhancement in its practice.

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