CITY OF SANTA BARBARA · 2017. 2. 21. · PF* PF* PF* PF* PF PF Benthic Topography 5 Land type...

Agenda Item No._____________

File Code No.

CITY OF SANTA BARBARA

COUNCIL AGENDA REPORT

AGENDA DATE: March 7, 2017

TO: Mayor and Councilmembers

FROM: Public Works Department, Water Resources Division

SUBJECT: Report On The Subsurface Intake And Potable Reuse Feasibility Studies

RECOMMENDATION:

That Council receive a presentation on the Subsurface Desalination Intake Initial Screening Analysis and Potable Reuse Feasibility Studies Report.

DISCUSSION:

At its meeting of September 23, 2014, Council directed staff to explore options for converting the existing offshore intake, sized and permitted to provide sufficient water for a 10,000 acre feet per year (AFY) desalination plant, to a Subsurface Seawater Intake (SSI) for the desalination plant, and evaluate opportunities for potable reuse as an alternative to desalination.

On January 30, 2015, the Regional Water Quality Control Board (RWQCB) adopted an amendment to the City’s El Estero Wastewater Treatment Plant National Pollutant Discharge Elimination System Permit (NPDES Permit) that incorporated Council’s direction to staff and added two milestones: submit a Feasibility Study Work Plan to the RWQCB by August 31, 2015, and report the findings of the Feasibility Study to the RWQCB at a public meeting, no later than June 30, 2017.

On May 5, 2015, Council approved a contract with Carollo Engineers, Inc. (Carollo), in the not-to-exceed amount of $343,925 to develop the Work Plan. The Work Plan was developed with input from the public and the National Water Research Institute Technical Advisory Panel (TAP) and included a public hearing in early August. The Work Plan included initial screening criteria to evaluate the technical feasibility of the different alternatives and assign them to one of three categories; infeasible, potentially feasible (but does not meet study goals), or potentially feasible. The Work Plan was submitted to the RWQCB in August 2015, and accepted in a letter dated October 20, 2015, from RWQCB staff.

Draft6-b

Council Agenda Report Report on the Subsurface Intake and Potable Reuse Feasibility Studies March 7, 2017

On September 22, 2015, Council approved a professional services contract amendment with Carollo in the not-to-exceed amount of $672,042 to provide a Desalination Subsurface Intake Initial Screening Analysis and a Potable Reuse Feasibility Study.

On January 27, 2016, a public workshop was conducted by the TAP to receive comments on Carollo’s SSI analysis. In accordance with the approved Work Plan, SSI alternatives were first evaluated for technical feasibility (i.e., "initial screening criteria"). The initial screening examined six SSI alternatives. Public comments were considered for incorporation into the screening analysis, as appropriate. The TAP reviewed work products (i.e., Work Plan, technical memos, reports, etc.) associated with the SSI initial screening. They also considered public comments, responses, and findings from other completed or ongoing similar efforts to develop the most informed recommendations, which can be found on the NWRI website: http://www.nwri-usa.org/santa-barbara-panel.htm. In summary, the TAP concurred with findings of the study that based on the criteria set forth in the RWQCB approved Work Plan, each of the six alternatives was determined to be either “not feasible” or "potentially feasible, but doesn't meet the study's objectives". Alternatives excluded from further study failed one or more of the following criteria: impacts to sensitive habitat areas, design and construction constraints, and seismic hazard/oceanographic factors. On March 22, 2016, Staff presented these findings along as part of a status report to the Council.

The public workshop for the Potable Reuse Feasibility Initial Screening Study was held on October 26, 2016. Similar to the format of the SSI study, a draft report was made available to the public and the TAP for review several weeks ahead of the meeting. Public comments were received, reviewed, and responded to by the TAP. Comments by the public and TAP were incorporated into the final report which can be found on the NWRI website: http://www.nwri-usa.org/santa-barbara-panel.htm. In summary, the TAP concurred with the findings of the study that although there were several alternatives for potable reuse that were technically feasible, the only viable option, direct potable reuse, lacked developed regulations that would allow it to move forward at this time.

The information from these studies will be useful in identifying additional water supply opportunities and assisting with the City’s next Long Term Water Supply Plan Update.

In compliance with the RWQCB’s amendment to the City’s El Estero Wastewater Treatment Plant NPDES Permit, staff will give a presentation on the Subsurface Desalination Intake Initial Screening Analysis and Potable Reuse Feasibility Studies Report to the RWQCB on May 11 or 12, 2017, in San Luis Obispo. The presentation to the RWQCB is the final requirement under the amended permit conditions.

This item was presented to the Water Commission on February 16, 2017.

PREPARED BY: Joshua Haggmark, Water Resources Manager/CT/RLR/kw

SUBMITTED BY: Rebecca J. Bjork, Public Works Director

Draft6-b

http://www.nwri-usa.org/santa-barbara-panel.htm



Council Agenda Report Report on the Subsurface Intake and Potable Reuse Feasibility Studies March 7, 2017

APPROVED BY: City Administrator’s Office Draft6-b

SantaBarbaraCA.gov/Water

PUBLIC WORKS DEPARTMENT

WATER RESOURCES DIVISION

Subsurface Desalination Intake

& Potable Reuse Feasibility Studies

Water Commission City of Santa Barbara, CAFebruary 16, 2017


Agenda• Feasibility Studies Background & Objectives• Subsurface Intake Study Summary

- Basis of Design/Conceptual Design- Initial Screening- Conclusions

• Potable Reuse Study Summary- Basis of Design/Conceptual Design- Initial Screening- Conclusions

• Study Summary


Feasibility StudiesBackground & Objectives


City Council & RWQCB directed City staff to evaluate the feasibility of subsurface intakes & potable reuse

• Scope of Study: “direct staff…[to evaluate the] feasibility, cost & timeline associated with both converting the offshore facility to a subsurface intake & look at the options about potable reuse” (City Council 9/23/14)

• Scope includes:- Identifying feasible alternatives

• Scope excludes:- Determining best alternative


Permit deadline drove the project schedule

• TAP Workshop #1 (Work Plans): 8/12/15

• TAP Workshop #2 (SSI Initial Screening): 1/27/16

• TAP Workshop #3 (Potable Reuse Initial Screening): 10/26/16

• TAP Workshop #4 (Feasibility Analysis): Not required

• RWQCB Presentation: 5/11/17 – 5/12/17


Work Plans define how the studies are to be conducted

1. Introduction

2. Basis of Design

3. Feasibility Criteria

4. Implementation Schedule Development

5. Cost Estimating Methodology

6. Feasibility Analysis

7. Technical Advisory Process

Work Plans have 7 sections that define study methods:

Approved by RWQCB October 20, 2015


Work product for both studies (SSI & PR) were completed in three Technical Memorandums (TM)

• TM 1 – Introduction and Background

• TM 2 – Regulatory and Permitting Requirements

• TM 3 – Basis of Design and Initial Screening Analysis


TM 1 provides study goals and approach

• RWQCB & City Council Requirements- Evaluate alternatives to desalination using screened open ocean

intake• First evaluate technical feasibility• Then, evaluate social, economic, & environmental feasibility for

technically feasible alternatives• Develop information that can inform future studies

- Understand maximum yield that is technically feasible


TM 2 presents regulatory & permitting requirements associated with SSI or PR alternatives

• Major permitting agencies include:- Army Corps of Engineers (ACOE)- California Coastal Commission (CCC)- State Water Resources Control Board (SWRCB)

- Division of Drinking Water (DDW)- Regional Water Quality Control Board (RWQCB)

- Santa Barbara County Public Health Department- City of Santa Barbara- Etc.


TM 3 presents basis of design for alternatives and initial screening results

• Each TM 3 (for SSI and PR studies) included:

- Introduction

- Basis of Design

- Including capacity, WQ, treatment requirements, site alternatives, project life, reliability, etc.

- Results of additional analyses

- Hydrogeological modeling, oceanographic hazards, sediment transport, etc.

- Conceptual Design

- Initial Screening Analysis

- Conclusions and Recommendations


• Included analysis of maximum yield that is technically feasible, even if the yield is not sufficient to fully replace:

- Desal Screened Open Ocean Intake, or

- Desal Plant Production

• Will be used to inform future studies

Basis of Design


Alternatives fell under the following categories during the initial screening of technical feasibility :

1. Infeasible (NF)

2. Potentially feasible, does not meet Study goals (PF*)

3. Potentially feasible (PF)

Only “PF” alternatives were evaluated for social, environmental & economic feasibility

• Process approved by RWQCB October 20, 2015


Subsurface Intake (SSI)

Study Summary


Project capacity

• Replace City’s existing screened open ocean intake

• Provide seawater for build-out capacity of 10,000 AFY

- Design capacity: 15,898 gpm

- Includes:

• 45% RO recovery

• Volume of raw water needed for pretreatment backwashing


Site alternatives• Onshore/Offshore Considerations:

- Dependent on intake technology

- Offshore areas within ½ mile offshore

- Property acquisition

- Avoids fault crossing


Intake technologies• Based on state of intake technology & recent studies

conducted by others:

Slant WellsSubsurface Infiltration

Galleries (SIG) – offshoreHDD wells

(i.e., Neodren)

Vertical WellsLateral Beach Wells(Onshore Infiltration

Galleries)

Radial Collector Wells(i.e., Ranney Wells)


Conceptual designs developedfor alternatives

• Based on greatest production capacity if unable to meet 10,000 AFY production requirement

• 9,000 ft. of beach available for SSI development

- East Beach: 5,300 feet

- West Beach: 1,300 feet

- Leadbetter Beach: 2,400 feet

• Property available (condemnation not required)

• Assume re-use of existing intake pipeline


Maximum water yield from SSI alternatives obtained


Initial screening resultsInitial Screening Criteria

Vertical Beach

Wells

Onshore

Infiltration

Gallery

Radial Collector

Wells Slant Wells

Subsurface

Infiltration

Galleries HDD WellsGeotechnical Hazards

1 Seismic Hazard

a. Project facilities would cross a known fault line, or be exposed to a seismic hazard that could otherwise not be protected from loss by design PF PF PF PF NF PF

Hydrogeologic Factors

2Impact on existing freshwater aquifers, local water supplies, or existing

water users

a.Volume of groundwater in storage is reduced due to subsurface intake pumping, impacting drought supply & requiring additional desalination to make up for loss of groundwater.

PF PF PF PF PF PFb. Operation of subsurface intake causes salt water intrusion into groundwater

aquifers. PF PF PF PF PF PF3 Impact to sensitive habitats such as marshlands, drainage areas, etc.

a. Operation of subsurface intake drains surface water from sensitive habitat areas or adversely changes water quality. NF NF NF NF PF PF

4Insufficient length of beach available for replacing full yield derived from

existing open ocean intake.

a. Small individual facility yield, large number of facilities required, & minimum spacing between facilities requires more shoreline than is available. PF* PF* PF* PF* PF PF

Benthic Topography

5 Land type makes intake construction infeasible.

a. Depth to bedrock too shallow (i.e., less than 40-feet deep); rocky coastline; cliffs PF PF PF PF PF PFOceanographic Factors

6 Erosion, sediment deposition, sea level rise, or tsunami hazards.

a.Oceanographic hazards make aspects of the project infrastructure vulnerable in a way that cannot be protected &/or would prevent the City from being able to receive funding or insurance for this concept.

PF PF (4) PF PF NF PF

Notes:

(1) NF = Not Feasible(2) PF = Potentially Feasible(3) PF* = Potentially Feasible, but does not meet current study goals(4) Potentially feasible at Leadbetter & West Beach only. Sediment transport conditions at East Beach make the implementation of an onshore infiltration gallery infeasible (refer to Section 3.4.2).


Initial screening results (continued)

Initial Screening Criteria

Vertical Beach

Wells

Onshore

Infiltration Gallery

Radial Collector

Wells Slant Wells

Subsurface

Infiltration

Galleries HDD WellsPresence of Sensitive Habitats

7 Proximity to marine protected areas

a. Location would require construction within a marine protected area. PF PF PF PF PF PFDesign & Construction Constraints

8 Adequate capacity

a. Subsurface material lacks adequate transmissivity to meet target yield of at least 15,898 gpm (i.e., build-out intake capacity necessary to produce 10,000 AFY). NF NF NF NF PF PF

9 Lack of adequate linear beach front for technical feasibility

a. Length of beachfront available is not sufficient for construction of the required number of wells of all or portion of intake to meet target yield. NF NF NF NF PF PF

10 Lack of adequate land for required on-shore facilities

a. Surface area needed for on-shore footprint (i.e., pump house) of an intake unit is greater than the available onshore area. PF PF PF PF PF PF

b. Requires condemnation of property for new on-shore intake pumping facilities. PF PF PF PF PF PF11 Lack of adequate land for required on-shore construction staging

a. The amount of land available to stage construction does not meet need. PF PF PF PF PF PF12 Precedent for subsurface intake technology

a. Intake technology has not been used before in a similar seawater or fresh water application at a similar scale. PF PF PF PF PF NF

Passes Initial Screening? Yes (Y) or No (N) N N N N N NNotes:

(1) NF = Not Feasible(2) PF = Potentially Feasible(3) PF* = Potentially Feasible, but does not meet current study goals(4) Potentially feasible at Leadbetter & West Beach only. Sediment transport conditions at East Beach make the implementation of an onshore infiltration gallery infeasible (refer to Section 3.4.2).


HDD wells conceptual design


HDD wells passed all initial screening criteria except for #12 - Precedent• No CA or U.S. experience• 10 years of global experience

- Inconsistent performance• “Not Feasible” conclusion supported by TAP assembled

by California Coastal Commission for proposed Huntington Beach desalination facility.

• Experience at San Pedro de Pinatar- Capacity loss & poor water quality- Expansion will use screened open ocean intake


SSI feasibility study recommends monitoring HDD technology• No alternative passed initial screening criteria

- One alternative constrained by seismic and oceanographic factors

- Four alternatives impacted sensitive habitat areas

- Five alternatives had design and construction constraints

• HDD technology is being tested by others

- SDCWA pilot test @ Camp Pendleton


Potable Reuse (PR)

Study Summary


Basis of Design for technical feasibility is determined by the following factors:

• Potable reuse application

- Non-Potable Reuse (NPR)

- Indirect Potable Reuse (IPR)

- Direct Potable Reuse (DPR)

• Water quality and treatment needs

• Treated water production capacity

• Subsurface properties and hydrogeologic considerations

• Available project sites

• Project life

• Reliability features


Target production capacity is specified in the Work Plan

• Yield based on City’s permitted desalination plant capacity

- 10,000 AFY

• City produces 1,400 AFY of NPR water

- PR alts cannot impact NPR production

• Combined PR and NPR production capacity

- 11,400 AFY

• El Estero WWTP Flow Characterization

- Annual, daily, and hourly flows


WWTP Flows – Percent Not Exceeded

ADF = 7.73 MGD (8,660 AFY)


Project Sites – IPR Alternative No. 1

Surface and subsurface application of recycled water in upgradient portions of the Foothill Basin and Storage Unit I


Non-Potable Reuse (NPR)

• Currently practiced by City

• Secondary effluent treated with MF & chlorination

• For study, it is assumed that NPR facilities will be relocated to Annex Yard

- Incorporated into new IPR or DPR AWTF

- Free up space at El Estero WWTP site

- Consolidation of treatment equipment & operations expertise


IPR process is dictated by Title 22 requirements


DPR process based on most recent regulatory activity and precedents in CA


Summary of Potential Maximum Yields

Alternative

Number

Potential Maximum Yields (AFY)

NPR Yield IPR Yield DPR Yield Total YieldAlt. 1A 716 0 6,355 7,071

Alt. 1B 0 0 6,928 6,928

Alt. 2A 1,400 0 5,808 7,208

Alt. 2B 0 0 6,928 6,928

Alt. 3A 1,400 5,808 0 7,208

Alt. 3B 0 6,928 0 6,928


Final summary of PR alternatives


Alternative 1A – Pipeline Alignment


Advanced Water Treatment Facility (AWTF) sited on Annex Yard property


Initial screening resultsPotable Reuse Alternative


Alternative

1A

Alternative

1B

Alternative

2A

Alternative

2B

Alternative

3A

Alternative

3BGeotechnical Hazards

1 Seismic Hazard

a. Project facilities would cross a known fault line, or be exposed to a seismic hazard that could otherwise not be protected from loss by design PF PF PF PF PF PF

Hydrogeologic Factors

2 Operation of groundwater replenishment facilities (i.e., injection wells or

spreading basin) adversely impacts existing fresh water aquifers, local water

supplies or existing water users.

a. Insufficient travel time (e.g., < 2 months) between groundwater replenishment point and other groundwater users. PF(4) PF(4) PF(4) PF(4) PF PF

3 Operation of groundwater replenishment facilities (i.e., injection wells or

spreading basin) adversely impacts sensitive habitats such as marshlands,

drainage areas, etc.

a. Operation of facility adversely changes water quality of habitat (e.g., salt water habitat becomes fresh water). PF(4) PF(4) PF(4) PF(4) PF(5) PF(5)

4 Insufficient storage space

a. Groundwater basin lacks adequate storage capacity to receive 10,000 AFY (or 11,400 AFY) at build-out PF(4) PF(4) PF(4) PF(4) PF* PF*

b. Groundwater replenishment of IPR water causes loss of ability to adequately manage the groundwater basin (e.g., artesian or flooding conditions, loss of stored water, etc.) PF(4) PF(4) PF(4) PF(4) PF PF

c. Groundwater replenishment of IPR water does not result in an increase in total basin yield and overall yield of 10,000 AFY (or 11,400 AFY). PF(4) PF(4) PF(4) PF(4) PF* PF*

Oceanographic Factors

5 Sea level rise or tsunami hazard

a. Oceanographic hazards make aspects of the project infrastructure vulnerable in a way that cannot be protected and/or would prevent the City from being able to receive funding or insurance for this concept PF PF PF PF PF PF

Notes:1) NF = Not Feasible2) PF = Potentially Feasible3) PF* = Potentially Feasible, but does not meet current study goals4) Potentially feasible because alternative does not include an IPR component. Thus, this initial screening criteria is not appl icable.5) Additional study will be required to locate groundwater replenishment wells at locations that will not adversely affect sensi tive areas or other users.


Initial screening results (continued)Potable Reuse Alternative


Alternative

1A

Alternative

1B

Alternative

2A

Alternative

2B

Alternative

3A

Alternative

3BPresence of Sensitive Habitats

6 Habitat creation

a. Facility creates habitat that is unsustainable (i.e., requires continued discharge by IPR or DPR facility) or adversely affects local ecosystem PF PF PF PF PF PF

Design and Construction Issues

7 Adequate capacity

a. Availability of effluent needed to produce 10,000 AFY (or 11,400 AFY) of recycled water at build-out PF* PF* PF* PF* PF* PF*

b. IPR or DPR production capacity and/or aquifer losses result in less than 10,000 AFY (or 11,400 AFY) of production at build-out PF* PF* PF* PF* PF* PF*

8 Lack of adequate land required for IPR or DPR treatment facilities or groundwater replenishment facilities

a. Surface area needed for footprint of IPR or DPR treatment facilities or groundwater replenishment facilities is greater than what is available. PF PF PF PF PF PF

b. Requires condemnation of property for new injection well facilities.PF(4) PF(4) PF(4) PF(4) PF PF

Passes Initial Screening? Yes (Y) or No (N) N N N N N NRegulations Exist in CA? Yes (Y) of No (N) N N N N Y Y

Notes:1) NF = Not Feasible2) PF = Potentially Feasible3) PF* = Potentially Feasible, but does not meet current study goals4) Potentially feasible because alternative does not include an IPR component. Thus, this initial screening criteria is not applicable.5) Additional study will be required to locate groundwater replenishment wells at locations that will not adversely affect sensitive areas or other users.


None of the PR alternatives met study goals & survived initial screening

• DPR - 4 alternatives passed all initial screening criteria, except for one – adequate capacity

- Limited availability of effluent from El Estero WWTP

- Unable to produce 10,000 AFY (or 11,400 AFY)

• IPR alternatives did not meet additional study criteria:

- Insufficient groundwater storage capacity, regardless of available effluent


Several alternatives discounted from further study prior to initial screening• Use of AWTF product water for diluting intake water at

desalination plant- Low recovery rate and high product water loss

• Seawater intrusion barrier (IPR Alternative No. 2)- Not effective due to excessive water loss

• IPR by surface application (i.e., spreading)- Liquefaction, slope failure, high groundwater,

mobilization/capture of contamination, impacts to sensitive habitats

- Small potential recharge


DPR Coalition• The State Water Resources Control Board (SWRCB) is pushing forward with

development of DPR guidelines and regulations• SWRCB Division of Drinking Water concluded in late 2016 that it is feasible to

develop regulations for DPR in California• The City is teaming up with 3 other Water Agencies to put forth plans for how DPR

might work for each agency - Agency’s include:

- City of Santa Barbara - City of Ventura - San Francisco Public Utility Commission - Los Angeles Department of Water and Power

• Plan to present findings to SWRCB to help with development of regulations• The project will be facilitated by the National Water Research Institute (NWRI)

with support from the Water Environment & Reuse Foundation (WE&RF).

40


Study Summary


SSI & PR Studies provide valuable information for future City planning efforts• The information in this study will be used in the next

Long-Term Water Supply Plan (LTWSP) Update- Update to reflect:

- New Drought of Record - Pending Cachuma environmental decisions- Pending re-assessment of Cachuma operational yield- New normal for water usage and conservation

• SSI & PR alternatives, along with other potential options, to be evaluated in the LTWSP Update


PUBLIC WORKS DEPARTMENT

WATER RESOURCES DIVISION

Questions?

Water CommissionCity of Santa Barbara, CAFebruary 16, 2017


Blank

44


Vertical wells conceptual design


Project Sites – IPR Alternative No. 2

Subsurface application of recycled water to create a seawater intrusion injection barrier

CITY OF SANTA BARBARA · 2017. 2. 21. · PF* PF* PF* PF* PF PF Benthic Topography 5 Land type...

Documents

Transcript of CITY OF SANTA BARBARA · 2017. 2. 21. · PF* PF* PF* PF* PF PF Benthic Topography 5 Land type...