Project Background
Objective
LADWP began construction to install a floating cover over the open water surface of the existing Upper Stone Canyon Reservoir in July of 2017. Two United States Environmental Protection Agency water quality regulations necessitate this improvement and are described as follows:
- Stage 2 Disinfection and Disinfection By-Products Rule (S2DBPR):
Addressing risks from microbial pathogens and disinfectants/disinfection byproducts, the S2DBPR requires compliance with new disinfection byproduct standard by April 1, 2012. A compliance extension of two years to April 1, 2014, was granted.
- Long Term 2 Enhanced Surface Water Treatment Rule:
Two options are allowed under this rule for open finished water reservoirs: (1) covered storage, or (2) a filtration plant at the outlet of the open reservoir. An approved compliance plan, required by April 1, 2009, has been approved by the California Department of Public Health.
In order to meet these two regulations at Upper Stone Canyon Reservoir, the LADWP is planning to do the following:
- Switch the promary disinfectants from chlorine to chloramines
- Cover Upper Stone Canyon Reservoir with a flexible membrane floating cover
General History
Upper Stone Canyon Reservoir is located just north of Lower Stone Canyon Reservoir; together these two reservoirs create the Stone Canyon Reservoir Complex. Constructed in 1957, this 14.5 acre reservoir has a capacity of 137 million gallons and supplies gravity fed water to the areas of West Los Angeles, Pacific Palisades, and the Marina Del Rey/LAX vicinity, in addition to the Beverly Glen area via the Stone Canyon Pump Station. Upper Stone Canyon Reservoir supplies water to over 450,000 people.
Scope of Project
Upper Stone Canyon Reservoir will remain in its existing configuration and a flexible membrane installed over the entire water surface, maintaining the current 137 million gallon storage volume. The cover material will be a polyethylene synthetic rubber similar to Hypalon® and anchored to the edge of the reservoir basin above the top water elevation. Larger in area than the reservoir surface, the cover will float on the water surface, adjusting as needed to the changing water levels. In order for the floating cover to operate more efficiently, protruding structures within the reservoir basin will be removed and replaced with underground equipment. In addition, the reservoir liner will be evaluated and possible replaced, as well as other improvements to supporting facilities.
The project requires a minimal amount of ground disturbance and a relatively low level of construction activity. It is the least expensive means of covering the water supply to achieve the LT2ESWTR and Stage 2 D-DBPR objectives. This type of facility requires more maintenance, including replacement every 20 years due to deterioration. Preliminary project cost for the floating cover is approximately $35 million. This is a 60-year lifecycle cost and includes two cover replacements. Construction is anticipated to last 1 ½ years.
Environmental Documentation
Notice of Preparation (NOP)
The 30-day public comment period for the NOP commenced on June 23, 2008, and concluded on July 22, 2008. On July 14, 2008, the LADWP held a public scoping meeting. Comments received during the public scoping period were considered during the preparation of the Draft EIR.
Environmental Impact Report (EIR)
The Draft EIR was completed in Spring 2011. The Final EIR includes all comments received on the Draft EIR along with the Response to Comments. The Final EIR was approved by the Board of Water and Power Commissioners on February 7, 2012 and the floating cover was selected as the project on this date. All environmental documents for this project are availalbe for review
LADWP Contact Information
Tatiana Tlatenchi, Project Manager, (213) 367-1664, [email protected]
Jason Stinnett, Community Relations, (213) 367-3803, [email protected]
Updated November 15, 2017