Orange County Branch Newsletter

July 2017

Environmental and Water Resources Institute

Peters Canyon Wash Channel Water Capture and Reuse Pipeline Project

By Remi Candaele

The ASCE OC EWRI Committee invited Amanda Carr (County of Orange), Joe McGehee (Irvine Ranch Water District (IRWD)), and Ray Bennett (IRWD) to discuss the history, coordination efforts, and engineering principles of the Peters Canyon Wash Channel Capture and Reuse Pipeline Project.  The project was recently recognized as the 2016 Environmental Engineering Project by the Orange County Branch.

To understand the environmental benefits of the project, one need to look at the history of the Santa Ana Delhi and the development of the City of Irvine. Historically, the Newport Bay Watershed would resembled to a large swamp, also known by the Spaniards as Cienega de las Ranas.  As agricultural activities and development started to take place in the watershed, drainage channels were constructed to lower the water table and evacuate the runoff from the foothills directly to the Ocean.  Amanda explained that the lowering of the water table led to the remobilization of selenium, a heavy metal that had naturally accumulated in the environment.  The remobilized selenium would enter the local food chain, and ultimately local organisms such as birds and fishes through bioaccumulation.

Because the level of bioaccumulation in organisms was found to exceed the toxic level limits established by the Environmental Protection Agency, a Total Daily Maximum Load (TMDL) was adopted in 2002 that requires the Stakeholders of the watershed to develop a restoration project and ultimately implement restoration projects to restore the levels of selenium below the toxic levels.

As part of the Nitrogen and Selenium Management Plan developed by the Stakeholders in 2009, the Peters Canyon Wash Pipeline Project was identified as an effective selenium load reduction Best Management Practice. The project consists of capturing flows from Peters Canyon Wash near Como Channel and Valencia Storm Channel and convey them to the OCSD facility in Fountain Valley.

Amanda described the Project Partners to be the Cities of Irvine and Tustin, the County of Orange, Caltrans, IRWD, but also the Orange County Sanitation District and the Orange County Water District.

Grant funding was successfully obtained from the State ($1.0M for Proposition 84) and the Orange County Transportation Authority ($3.2M for Measure M2).  The agencies who signed the multi-agency agreement benefited from selecting a consultant that already had on-call contracts with each agency.

Joe mentioned that the final design was completed in February 2015 and notice to proceed with construction was issued as early as June 2015 to the retained contractor.  Construction completed in June 2016.  About 17,000-feet of PVC and CML&C steel pipe were installed with the Orange County Flood Control District right-of-way and underneath the existing bike trails.  Joe identified several key points for the project:

Jack and bore techniques were used to run the pipeline underneath the Metrolink railroad at Como Channel.  Multiple unknown utility lines were encountered during jack and bore operations.
Three diversion structures were constructed at Moffett Drive, Edinger Avenue, and Como Channel. All are controlled on variable frequency drives and are flow controlled.
A connection to the Caltrans Groundwater Treatment Facility (GWTF) was also constructed near Walnut Avenue
Ultimately, the project connects to the OCSD 66-inch trunk sewer line in Main Street

The total cost for the project, including design and construction phases, approximates $10.5M.

Ray presented on the multiple lessons and challenges for the project:

The San Joaquin Marsh was prior to completion of this project already an existing water quality Best Management Practice that was designed to treat dry-weather runoff.  An impact avoidance framework was developed to recirculate flows and pond levels within the Marsh in order to counter the 19% reduction in dry-weather runoff to the Marshes.
The multi-agency agreement acknowledges the main purpose of the right of way, being for flood control and active transportation.  It provides actions if future circumstances require relocation of the pipeline.
As runoff is diverted to the OCSD sewer trunk line, negotiations were held to revise the volumetric limits of the OCSD Urban Runoff Diversion Program for dry-weather flows.

The ASCE OC EWRI Committee would like to thank Amanda Carr, Joe McGehee, and Ray Bennett for an insightful presentation that was well received by more than 40 attendees. 

Additional acknowledgments: Jose Cruz and Penny Lew for spearheading the logistics of the event, the EWRI Committee (Roger Chung, Jennifer Marks, Jenny Robinet) for welcoming the attendees. 

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