OCSD has made a commitment to energy neutrality. A feasibility study for activities that can be 
undertaken has been assigned to the Process Engineering team (Business Accountability Charter, 

OCSD has been generating its own power since 1993 and currently produces 66% of the power required 
for Plant operations.  Each facility has its own Central Power Generation (CenGen) capabilities that can 
provide heat and power for the facilities through the combustion of digester (methane) gas.  This 
process meets stringent South Coast Air Quality Management District (AQMD) emission standards thus 
allowing OCSD to minimize its purchase of grid power, resulting in $6 million in savings annually. 

In striving to meet AQMD air quality emission standards, OCSD demonstrated innovation and originality 
in upgrading our CenGen units, as catalytic converters are not commonly found on engines of this size. 

OCSD central power generation creates a triple bottom line of sustainability: social and environmental 
(reduced emissions, decreased need to flare off digester gas as a waste product), and financial 
(decreased need to purchase power from the grid.) 

Performance Measures & Results 



Increase Renewable Energy Use: OCSD uses more than 96% of digester produced methane gas 
annually to produce 2/3 of its internal energy (power) requirements and heat for digestion 
processes (steady state). 



Decrease dependency on power grid: More than 130 million kilowatt hours required annually by 
plant processes; OCSD produces an average of 89 million kilowatt hours resulting in a decreased 
dependency on the local power grid (steady state, 10-year average).  Due to improvements in 
emissions reductions from central generation engines, OCSD will be able to increase internal 
power production capacity beginning in 2016.  



Cost avoidance: OCSD realizes more than $6M in annual cost avoidance by producing its own 
power.  Avoidance is realized by rate payers. 




Board/executive management reuse strategy established 


Communications and outreach plan developed and implemented  


Ongoing market assessment of reused water to public/private and public/public entities 


Investments in reuse infrastructure  

Groundwater Replenishment System (GWRS) – Reuse strategy has been in place since 1991 with influent 
processed as non-potable water for landscape irrigation. In 2008, a strategy was established to 
transition OCSD influent to potable water.  

Public Outreach: “No Drugs down the Drain” and “What to Flush” outreach programs. Participation in 
community outreach events and presentations. Posting to social and traditional media sources.  Hosting 
on-site tours that explain treatment processes. 

In 2013, began using plant water to cool the facilities’ power generation engines. Currently, Plant 1 uses 
5.5 mgd of plant water; and Plant 2 uses 4.1 mgd.