Demonstration of Ocean Plan Consistency during CEQA Review Subsurface Intake Feasibility Analysis (Case Study) Zita Yu, PhD, PE Water Resources Engineer CalDesal Conference 2018 February 1, 2018 1
Outline West Basin Municipal Water District West Basin s Ocean Water Desalination Project CA Ocean Plan: Intakes Subsurface Intake Technology Overview Case Study: Santa Monica Bay Summary 2
WEST BASIN MUNICIPAL WATER DISTRICT 3
Elected Board of Directors Division I: HAROLD C. WILLIAMS Secretary Division II: GLORIA D. GRAY Treasurer Division III: CAROL W. KWAN Board Member Division IV: SCOTT HOUSTON Vice President Mission: Provide a Safe and Reliable Supply of High Quality Water to Communities We Serve Services: Imported potable water Tailored recycled water Conservation 4 Division V: DONALD L. DEAR President
Pre-1947 Water Supply Portfolio 100% Groundwater (Retailers and Cities) 5
1990 Water Supply Portfolio 20% Groundwater (Retailers and Cities) 80% Imported Water (West Basin) 6
2015 Water Supply Portfolio 19% Groundwater (Retailers and Cities) 9% Recycled Water (West Basin) 16% Conservation (West Basin + Retailers) 55% Imported Water (West Basin).4% Brackish Desal (Retailer) 7
Potential 2025 Water Supply Portfolio from UWMP 14% Non-Potable Recycled Water (West Basin) 18% Groundwater (Retailers) 39% Imported Potable Water (West Basin) Imported Supplies: from 55% to 39% Recycled Supplies: from 9% to 14% 18% Conservation (West Basin + Retailers) Conservation: from 16% to 18% 11% Local Potable Desalinated Ocean Water (West Basin) 8
Ocean Water Desalination Program Step-wise Approach Pilot Study (2000 2008) Demonstration Facility (2008-2017) EIR Preparation (2015 Present) EIR Certification and a Board Decision (TBD) Permitting (if approved by Board, TBD) 9
CEQA Review West Basin MWD Lead agency Project proponent Review Scope: Local Project: 20 MGD Initial project Reviewed at the project level Regional Project: up to 60 MGD Potential future expansion Reviewed at the project/programmatic level 10
CA OCEAN PLAN INTAKE REQUIREMENTS
Intake Requirements A subsurface intake system is preferred. If not feasible*, screened intake should be used. Consideration of a range of feasible* alternatives for the best site, design, technology, and mitigation measures to minimize intake and mortality of all forms of marine life.(water Code 13145.5(b) Feasible means capable of being accomplished in a successful manner within a reasonable period of time, taking into account economic, environmental, social, and technological factors. (Public Resources Code 21061.1; 30108) 12
SUBSURFACE INTAKE TECHNOLOGIES
Subsurface Intake Overview Types: Well systems (geological and hydrogeological dependent) Infiltration galleries (sediment transport process dependent) Benefits: Eliminate impingement and entrainment of sea life Potentially improve intake water quality Factors for determining feasibility: Coastal geological and hydrogeological conditions Coastal aquifer and ocean water interaction Coastal sediment transport processes Onshore site availability Absence of ecologically sensitive area Constructability Technology reliability Life cycle costs 14
Well Systems 15
Wells: Fresh Groundwater Interference 16
SSI Infiltration Galleries Average annual bed elevation change should be <0.5ft 17
CASE STUDY SANTA MONICA BAY
Wells: Groundwater Conditions and Rights 19
Wells: Seawater Barrier Project West Coast Seawater Barrier Project 20
Infiltration Galleries: Sand Transport Mugu Canyon Dune Canyon Redondo No limestones formation Canyon 21
Ballona Creek Nourished Beaches Coastline with sand nourishment Coastline without sand nourishment 22
Nearshore Geology: Impervious Layer and Cobbles 23
Coastal Site Zoned for Industrial Uses 24
Ecologically Sensitive Area 25
Subsurface Intake Feasibility Findings Wells and infiltration galleries: Evaluated 9 technologies None of them are feasible in Santa Monica Bay Major constraints: Nearshore: Interference with seawater barrier operations Presence of coastal contaminated groundwater plumes Groundwater adjudication Shallow clay lenses Cobbles Erosive nearshore seabed with high elevation fluctuations Offshore: Rough offshore sea conditions Unproven technology reliability High costs 26
Summary Subsurface intake (SSI) feasibility analysis is necessary to demonstrate consistency with Ocean Plan requirements during the CEQA process. The followings are important factors to consider to evaluate SSI feasibility: Coastal sediment transport processes Coastal geological and hydrogeological conditions and interaction Ecologically sensitive area Onshore site zoning and availability Constructability Technology reliability Life cycle costs Others, e.g. water rights 27
Thank you! Zita Yu, PhD, PE zitay@westbasin.org http://www.westbasindesal.org/ 28 http://www.westbasindesal.org/