Brian Villalobos, CHG, CEG GEOSCIENCE Support Services, Inc. American Water Works Association California-Nevada Section Reno, Nevada

Transcription

1 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

2 Introduction Subsurface 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.

3 Introduction 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

4 Conditions Favorable for Subsurface Intake Systems: Areas where delta deposits are present near shore beneath the Ocean, Where aquifer systems extend offshore, and Ocean discharge points of major drainages.

5 Conditions Favorable for Subsurface Intake Systems Delta Deposits Beneath the Ocean River Delta Deposits Ocean 5 5

6 Conditions Favorable for Subsurface Intake Systems Aquifer Systems Extending Offshore Ocean Land 6

7 Areas Favorable for Subsurface Intake Systems Discharge of Major Drainages into the Ocean 35 0 Oxnard L. Arrowhead Big Bear L Santa Cruz Is. Point Dume Santa Monica Los Angeles Santa Fe Dam Claremon t Prado Dam Riverside San Bernardi no N Palos Verdes 0 50 mi San Nicolas Is. Santa Catalina Is. Dana Point Oceanside Carlsbad Pal a Lake Henshaw

8 MPWSP will: California American Water Monterey Peninsula Water Supply Project (MPWSP) Case History 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

9 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).

10 MPWSP: MPWSP Case History Adds New Water Supply to the Region Does Not Interfere with Existing Water Rights Will Result in Local Halting even Reversal of Seawater Intrusion

11 Slant Well Desalination Feedwater Supply System To Fresh Water Supply Desalination Plant Infiltration From Ocean Slant Well Desalination Feedwater Supply 3

12 CalAm s Study Area: Moss Landing CEMEX near Marina

13 Study Area Groundwater Subbasins

14 MCWRA Contours Moss Landing CEMEX Seawater Intrusion in the 180-Foot Aquifer Seawater Intrusion in the 400-Foot Aquifer

15 Regional Geology

16 Key Project Considerations: Capacity of Sediments to Provide Design Volumes Impacts to Other Wells Encroachment on Water Rights Impacts to Seawater Intrusion

17 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 Project

18 CalAm s Phase 1 Study: 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

19 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

20 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

21 Initial Construction of Groundwater Model Constructed for Previous Projects in 2008: Regional Water Supply Project Model SVIGSM Regional Model 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

22 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

23 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

24 Hydrologic Investigation Data Collection Field Work conducted between September 2013 to April Sonic Boreholes 200 to 347 feet in Depth with Continuous Soil Cores Geophysical Logging of all Boreholes Sonic Core

25 Hydrologic Investigation-cont Boreholes used for Water Quality Sampling Boring: Showing Vertical Distribution of TDS 31 - Zones (temporary wells) for Water Quality Sampling-Vertical Variations in Water Quality and Age Dating Zone Construction

26 Water Quality Sampling Moss Landing CEMEX Zone No. ML-1 ML-2 ML-3 ML-4 ML-6 PR-1 MDW-1 CX-B1 WQ CX-B2 WQ CX-B4 Zone 1 (ft bgs) Zone 2 (ft bgs) Zone 3 (ft bgs) Zone 4 (ft bgs) Zone 5 (ft bgs) Zone 6 (ft bgs) Total Depth (ft bgs)

27 Hydrologic Investigation-cont Mechanical Grading Analysis for Initial Evaluation of Hydraulic Conductivity (K) Krumbein-Monk Mechanical Grading Plot Kozeny-Carman Hazen Approximation Estimated Hydraulic Conductivities

28 Hydrologic Investigation-cont. Age Dating using Tritium and Hydrogen/Oxygen Isotope Analysis Tritium Results above: Upper Aquifers show Recharge with more Recent Water Hydrogen/Oxygen Isotope plot to left show Groundwater at CEMEX is Intruded Seawater

29 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

30 Regional, Local, and Focused Groundwater Models

31 Well and Cross-Section Locations

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33 Geologic Cross-Sections

34 Hydrostratigraphy

35 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

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

37 Design and Modeling of Test Slant Well and Full- Scale Project Full-Scale System Modeling Results are Progress to Complete In October

38 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 supply development, and MPWSP can result in a long-term sustainable water supply providing New water for the Monterey Peninsula.

39 Questions?