Project Phases

Current Activities and Studies

Entrainment Study

The Entrainment Study and Impact Assessment is intended to support the investigation of the potential screened open intake approach for the full scale facility, as well as to support the proposed project specific EIR and permitting. A Technical Working Group (TWG) has been formed to provide review throughout the study.

 

Tenera Environmental is currently performing  the 13-month entrainment study.  This Study Plan is based on a survey of available background literature, and results of intake system studies at power plants and demonstration studies at other desalination facilities in California.

 

The proposed scwd² open ocean intake would be sited near the end of an abandoned 36-inch wastewater outfall that is located approximately 1.5 mi southwest of Santa Cruz Harbor at a depth of 42 ft mean lower low water (MLLW).

 

Proposed open-ocean intake for the proposed plant may utilize the abandoned 36-inch wastewater outfall near Mitchell's Cove.

The scope of work described in the Entrainment Plan includes the following objectives:

• Establish a baseline characterization of larval fish, fish eggs, and target shellfish species by sampling the species composition, abundance, and temporal variability near the proposed intake.

• Assess the operational effectiveness of the proposed narrow-slot cylindrical wedgewire screen intake in preventing entrainment by sampling with a pilot-scale screened intake.

• Model the potential impacts on local fish and target shellfish populations caused by the loss of entrained organisms, and evaluate their ecological and market value.

 

  Regulators require that the design and operation of open ocean intakes minimize adverse environmental effects or impacts. The overall approach, consistent with Section 316(b) studies  shall collect data on the concentrations of fish eggs, fish larvae, and target shellfish larvae in the source water at the proposed intake by using towed plankton nets, the standard sampling method for these organisms. The nets are equipped with calibrated flow meters that measure the volume of water sampled. The number of organisms collected and the volume of seawater sampled are used to calculate sample concentrations for each taxon [a distinct taxonomic category] of fish eggs, fish larvae, and target shellfish larvae. Similar data is also being collected from a pilot project pump and screening system tested on a platform near the end of the Santa Cruz Municipal Wharf. Two pumps are set up on the platform to collect screened and unscreened samples simultaneously. Screening efficiency will be evaluated by comparing larval concentrations from the two samples.

Paired plankton nets are used to collect fish and shellfish larvae in the source water. 

 

Because subsurface wells could provide a benefit in minimizing entrainment of marine organisms and provide a level of particulate pretreatment, scwd² proposes to continue to investigate subsurface wells in parallel with a screened open water intake approach.