Subsea Groundwater for Desalination

Feedwater Supply

Case Study: Feasibility of Using Subsurface

Intake Systems in the Marina/Moss Landing

Area of California

Brian Villalobos, CHG, CEG

GEOSCIENCE Support Services, Inc.

American Water Works Association

California-Nevada Section

Reno, Nevada

October 1, 2014

IntroductionSubsurface intakes for Desalination are favored among regulatory agencies (e.g. Cal-SWRCB Ocean Plan

Amendment, 2014) because of:

(1) No Ocean Construction Impacts,

(2) Avoidance of Entrainment and Impingement Impacts to Marine Organisms, and

(3) No Permanent Visual Impacts to Coastal Areas.

Additionally, subsurface intakes are beneficial to plant operations by:

(1) elimination or reduction of costly pretreatment,

(2) protection from high turbidity storm surge and red tide events by natural filtration and pretreatment from ocean floor sediments, and

(3) minimal growth of marine organisms that occurs inside the intake pipeline

Introduction

• Areas where delta deposits are present near shore beneath the Ocean,

• Where aquifer systems extend offshore, and

• Ocean discharge points of major drainages.

Conditions Favorable for Subsurface

Intake Systems:

5

Conditions Favorable for Subsurface Intake Systems

5

Delta Deposits Beneath the Ocean

Ocean

River Delta Deposits

6

Conditions Favorable for Subsurface Intake Systems

Aquifer Systems Extending Offshore

Ocean

Land

Oceanside

Carlsbad

Pal

a

Los

AngelesSanta

Monica

San

Bernardi

no

Palos

Verdes

Dana

Point

Riverside

Santa

Fe

Dam

Prado

Dam

Santa

Catalina

Is.San Nicolas

Is.

Santa Cruz

Is.

Oxnard

Point

Dume

-1160-1170-1180-1190-1200

330

340

350

Lake

Henshaw

0 50 mi

Big Bear L.L. Arrowhead

N

Claremon

t

Areas Favorable for Subsurface Intake Systems

Discharge of Major Drainages into the Ocean

MPWSP will:

• Replace Water Supply that has Historically come from Carmel River

• Will Develop “New” Supply of 6.4MGD or 9.6MGD for Desalination Plant

• Will Construct an Innovative Project for Development of New supply

California American WaterMonterey Peninsula Water Supply Project

(MPWSP) – Case History

MPWSP – Case History

The slant well subsurface intake system is a primary consideration for this project because:

The system allows for feedwater supply to be obtained from ocean sources

(i.e., vertical leakage through the sea floor and horizontal recharge from offshore aquifers).

MPWSP:

• Adds New Water Supply to the Region

• Does Not Interfere with Existing Water Rights

• Will Result in Local Halting even Reversal of Seawater Intrusion

MPWSP – Case History

Slant Well Desalination Feedwater Supply System

Slant Well

Desalination Feedwater Supply

Desalination Plant

Infiltration From Ocean

To Fresh Water Supply

3

CalAm’s Study Area:

• Moss Landing• CEMEX near Marina

Study Area Groundwater Subbasins

Seawater Intrusion in the 180-Foot Aquifer

Seawater Intrusion in the 400-Foot Aquifer

CEMEX

Moss Landing

MCWRA Contours

Regional Geology

Key Project Considerations:

• Capacity of Sediments to Provide Design Volumes

• Impacts to Other Wells• Encroachment on Water Rights• Impacts to Seawater Intrusion

Cooperative Planning• Formation of a Technical

Group of Experts Representing Stakeholders

• Joint Development of an Investigation Workplan

• Joint Review of Technical Report and Model Construction

Monterey Peninsula Water Supply Projectwww.watersupplyproject.org

• Characterize the hydrogeologic conditions in the Marina and Moss Landing area,

• Determine Feasibility of using Slant Well Technology,

• Initial Modeling to Test Impacts

Phase II Work:• Construction and Long-Term Testing of a Test

Slant Well• Refine Model using Long-Term Test Data

CalAm’s Phase 1 Study:

Phase I - Scope of Work

• Initial Construction of Groundwater Model

• Hydrogeologic Investigation

• Update of Local and Regional Model and

Construction of a New Focused Model

• Design and Modeling of Test Slant Well and

Full-Scale Project

Phase I - Scope of Work

• Initial Construction of Groundwater Model

• Hydrogeologic Investigation

• Update of Local and Regional Model and

Construction of a New Focused Model

• Design and Modeling of Test Slant Well and

Full-Scale Project

Initial Construction of Groundwater Model

SVIGSM Regional

Model

Regional Water

Supply Project Model

Constructed for Previous Projects in 2008:

• Used Published and Unplublished Geologic and Hydrogeologic Data

• Used Data from Previous Groundwater Models

• Cell Size 200 ft. x 200 ft.• Moss Landing and Marina

Area

Phase I - Scope of Work

• Initial Construction of Groundwater Model

• Hydrogeologic Investigation

• Update of Local and Regional Model and

Construction of a New Focused Model

• Design and Modeling of Test Slant Well and

Full-Scale Project

Hydrogeologic Investigation

• Collection of Site Specific Geologic and Hydrogeologic Data

• Confirm or Modify Existing Hydrologic Conceptual Model

• Provide data to Refine and Update Groundwater Model

• Use Refined and Updated Model to Evaluate Project Impacts

• Field Work conducted between September 2013 to April 2014

• 13 – Sonic Boreholes 200 to 347 feet in Depth with Continuous Soil Cores

• Geophysical Logging of all Boreholes

Hydrologic Investigation Data Collection

Sonic Core

• 10 - Boreholes used for Water Quality Sampling

• 31 - Zones (temporary wells) for Water Quality Sampling-Vertical Variations in Water Quality and Age Dating

Boring: Showing Vertical

Distribution of TDS

Zone Construction

Hydrologic Investigation-cont.

Water Quality Sampling

Zone No. ML-1 ML-2 ML-3 ML-4 ML-6 PR-1 MDW-1 CX-B1 WQ CX-B2 WQ CX-B4

Total

Depth

(ft bgs)

350

237-247

  187-197 

  152-162 

60-70

300

306-316

248-258

155-165

110-120

58-68

51-61 -

200 200 200 201 200 200 306 250

- 84-94 -

Zone 6

(ft bgs)- - - - - -

Zone 5

(ft bgs)- - - - -

104-114

Zone 4

(ft bgs)- - - - - - 134-144 55-65

237-247 161-171

Zone 3

(ft bgs)- - - - - - 182-192

190-200 274-284 215-225

Zone 2

(ft bgs)90-100 90-100 103-113 74.5-84.5 100-110 125-135

Zone 1

(ft bgs)

113.5-

118.5167-177 180-190

163.5-

173.5152-162

Moss Landing CEMEX

78 - Mechanical Grading Analysis for Initial Evaluation of Hydraulic Conductivity (K)

Mechanical Grading Plot

Estimated Hydraulic Conductivities

Hydrologic Investigation-cont.

Krumbein-Monk

Kozeny-Carman

Hazen Approximation

Age Dating using Tritium and Hydrogen/Oxygen Isotope Analysis

Hydrologic Investigation-cont.

Hydrogen/Oxygen Isotope plot to left show Groundwater at CEMEX is Intruded Seawater

Tritium Results above: Upper Aquifers show Recharge with more Recent Water

Phase I - Scope of Work

• Initial Construction of Groundwater Model

• Hydrogeologic Investigation

• Update of Local and Regional Model and

Construction of a New Focused Model

• Design and Modeling of Test Slant Well and

Full-Scale Project

Regional, Local, and Focused Groundwater Models

Well and Cross-Section Locations

Geologic Cross-Sections

Hydrostratigraphy

Phase I - Scope of Work

• Initial Construction of Groundwater Model

• Hydrogeologic Investigation

• Update of Local and Regional Model and

Construction of a New Focused Model

• Design and Modeling of Test Slant Well and

Full-Scale Project

Design and Modeling of Test Slant Well and Full-Scale Project

Test Slant WellTest Slant Well

Design and Modeling of Test Slant Well and Full-Scale Project

Full-Scale System

Modeling Results are Progress to Complete In October

Conclusions• Two of the sites studied several are suitable sites for slant well

intake systems,

• Phase II Testing will Provide New Data that will Benefit the MPWSP and Others Seeking to Use Subsurface Intake Technology for Ocean Desalination,

• CalAm’s efforts are on the cutting edge of water supplydevelopment, and

• MPWSP can result in a long-term sustainable water supplyproviding “New” water for the Monterey Peninsula.

Questions?