Northern Cities Documents

Ocenao CSD board documents:

The following is the result of using acrobat to OCR all the online Oceano board agendas and then a search those files to find the text around and the page of the word "seawater" and create a link to the document:

ge Average Range Average Potential Source of Contamination Alum num ppb 200 ND 150 B1 ND Naturally present in the environment and residue from water treatment processes Chlor de ppm 500 20 14B 56 26 47 39 Runoff Ileac hing from natural deposits seawater influence Color CU 15 1.0 3.0 2 Ⰰ㈀ Naturally occurring organic materials Corrosivity LI Nat ural or industrially influenced Noncorrosive ⸀㐀 1.1 O B ⸀㌀ 1.22 Noncorrosive balance of hydrogen carbon and oxygen 0.92 in the water affected by temperat

Oceano_Docs/08_0101_OceanoCSD_water_quality---2008CCR2007Data.pdf#page=4

ure and other factors Odor Threshold 3 1 3 1.4 1.0 Nat urally occurring organic materials Specific Conductance 1600 337 760 632 990 1000 995 Runoff leaching from natural deposits micromhos seawater influence Sul f ate ppm 500 39 110 79 1BO 200 190 Runoff leaching from natural deposits industrial wastes Turb d ty NTU 5 ⸀　㌀ 2.9 OB ⸀㄀　 2.2 ⸀㄀㔀 Soil runoff Presence of colloidal and or suspended matter Total D ssolved SoHds ppm 1000 159 47

Oceano_Docs/08_0101_OceanoCSD_water_quality---2008CCR2007Data.pdf#page=4

rface Water Well Water Contaminants without a Drinking Water Standard Contaminant reporting units Range Average Range Average Potential Source of Contamination Alkal n ty as CoCO ppm 56 300 175 300 3BO 340 Runoff Ieaching from nat ural deposits seawater influence Calc um ppm 34 B6 65 120 130 125 Runoff leaching from natural deposits seawater influence Haloacetic Acids ppb 5.7 2B 17 NA By product of drinking water chlorination Hardness ppm 72 370 230 470 550 510 Generally found in ground and

Oceano_Docs/08_0101_OceanoCSD_water_quality---2008CCR2007Data.pdf#page=4

surface water Magnes um ppm 9.5 43 26 39 57 4B Runoff leaching from natural deposits seawater inf luence pH 7.3 9.5 B 17 7.0 7.9 7.6 Runoff leaching from natural deposits seawater influence Sod um ppm 23 45 34 39 45 42 Runoff leaching from natural deposits seawater influence Vanadium ppb 3.7 6.2 4.2 3.5 3 B 3.65 Runoff leaching from natural deposits seawater influence Table 6 Sampling Results Showing the Detection of L

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Water Management Plans UWMPs 5 2.2.3 Population 5 2.3 Water Supply 5 2.3.1 LopezSupply 5 2.3 ⸀㈀ State Water Project 5 2.3.3 Groundwater 6 2.3.3 I Pumping 6 2.3.3.2 Water Levels 6 2.3.3.3 Water Quality 7 2.3.3.4 seawater intrusion 8 3 Data Organization 10 4 Protocols 12 4 I Climate and Hydrology Data 12 4 I I Precipitation 12 4.1.2 Evapotranspiration 12 4.1.3 SurfaceWater 13 4.2 Groundwater Monitoring 13 4 1.4 Wells Used for Monitorin

Oceano_Docs/08_0709_OceanoCSD_BoD---20080709BoDMeeting.pdf#page=27

4803 X X 32S 13E 30F01 15 30 40 55 30F01 X X 32S 13E 30F03 305 372 30F03 X X 32S 13E 30N01 15 40 30N01 X X 32S 13E 30N03 60 135 30N03 X X 2.3.3.3 Water Quality Water quality is a key element of water supply Contaminants from anthropogenic sources or seawater intrusion can potentially impact the basin reducing the available water supply Currently the sole source of consolidated water quality information for the area is the California Department of Public Health DPH formally DHS The Northern Cities and o

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in cooperation with other local agencies in conjunction with depth to water measurement collection January April July and October The sentry wells shown on Figure 2 will be sampled quarterly for a range of constituents to detect the first signs of seawater intrusion These constituents include the major cations and anions plus selected constituents such as total nitrogen bromide and iodide The methodology of using water quality data to assess seawater intrusion analysis is discussed in the next section

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Water quality monitoring protocols are found in Section 4 2.3.3.4 seawater intrusion The NCMA is underlain by a coastal aquifer system that extends offshore The aquifers include an interface between freshwater and seawater While the location of the freshwater seawater interface s is not known there is currently an estimated net outflow of freshwater from the basin to the ocean and no known seawater intrusion Monitoring Program for Northern Cities Management Area 8 Jun

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st has multiple ports that monitor water levels at different elevations The water levels in all ports will be examined relative to one another to assess vertical differences and to mean sea level Water quality monitoring to provide early warning of seawater intrusion will focus on the sentry wells Depth specific monitoring of the sentry wells can help document the vertical variability of seawater intrusion if any Evaluation of water quality data will include time plots of specific constituent concentr

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ations for example chloride that are commonly used to identify freshwater and seawater mixing Other geochemical methods to identify seawater intrusion may be applied as warranted including preparation of Piper Schoeller and brine differentiation plots Monitoring Program for Northern Cilies Management Area 9 June 16 2008

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01 ASTM 2007 and the samples will be analyzed by a State Certified Laboratory for the major ions calcium bicarbonate carbonate chloride magnesium potassium sodium and sulfate plus selected constituents for seawater detection such as bromide iodide and total nitrogen When applicable water quality data will be collected consistent with Groundwater Ambient Monitoring and Assessment GAMA programs The GAMA policies and protocols are derived from U S Geological Sur

Oceano_Docs/08_0709_OceanoCSD_BoD---20080709BoDMeeting.pdf#page=42

Sources of Supply 5.1.1 Lopez 5.1.2 State Water Project 5.1 ⸀㌀ Developed Water 5 IA Groundwater 5.2 Groundwater Conditions 5.2 I Water Levels 5.2.1.1 Hydrographs 5.2.1.2 Change in Storage 5.2.2 Water Quality 5.2.2.1 Hydrographs 5.2.2.2 Trends 5.2.3 seawater intrusion 5.2.3.1 Water Levels 5.2.3.2 Water Quality 5.3 Threats to Water Supply 6 Comparison of Demand and Supply 7 Expected Future Conditions 8 Recommendations 9 References Monitoring Program for Nonhern Cities Managemenl Area 16 June 16 2008

Oceano_Docs/08_0709_OceanoCSD_BoD---20080709BoDMeeting.pdf#page=43

Oceano CSD Future Water Supply Groundwater 46 Lopez 16 Future water supplies were analyzed as part of the 1991 Water Master Plan and included several potential sources the State Water Project seawater Desalinization Wastewater Reclamation Water Fixture Retrofit Groundwater Management and the Nacimiento Project The District does have a share of State Water 750 acre feet which has yet to be fully utilized seawater Desalinization remains a potential

Oceano_Docs/08_0924_OceanoCSD_BoD---20080924BoDMeeting.pdf#page=30

EXECUTIVE SUMMARY Three agencies the City of Arroyo Grande the City of Grover Beach and the Oceano Community Services District Agencies have come together to participate in the evaluation of a potential drought proof water supply seawater desalination to supplement their existing potable water sources Currently all three Agencies receive water from various sources including the California State Water Project Lopez Lake Reservoir and groundwater from the Arroyo Grande PlainfTri Cities

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=8

ing study The study focused on utilizing the existing South San Luis Obispo County Sanitation District's SSLOCSD wastewater treatment plant site to take advantage of utilizing the existing ocean outfall while having the plant located near the ocean seawater source This February 2006 study concluded that desalination was a viable water supply and that further detailed study of this water supply alternative was warranted Subsequently the Agencies were successful in securing a Proposition 50 grant to help

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=8

r year AFY with each agency's share in the plant capacity as follows City of Arroyo Grande 750 AFY City of Grover Beach 800 AFY Oceano CSD 750 AFY Raw Water Supply A hydrogeologic study was conducted to assess the viability of various options of seawater intake by beach wells Open water intakes were considered too environmentally unfriendly and extremely difficult to permit with the California Coastal Commission The study concluded that a series of relatively shallow beach wells on the order of 70 f

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=8

eet deep would optimize draw of seawater and minimize draw of groundwater basin water from inland Actual pilot testing would be required to confirm the capacity of each beach well and to determine construction details and installation depths Based on the hydrogeologic study it is expected

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that for a series of 20 or more beach wells could be required to accomplish the seawater intake requirements 3,830 AFY of seawater to produce 2,300 AFY of fresh potable water A beach well gallery constructed on the State Beach would be required including a piping gallery and series of pumps to convey seawater to the SSLOCSD WWTP A 14 to 16 diameter pipeline would be required to

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convey the seawater to the plant Three alignment alternatives were considered as follows Alignment Option 1 Arroyo Grande Creek Levee From the beach well gallery the raw water pipeline would extend from the beach onto the north bank levee of Arroyo Grande Creek enteri

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=8

r Quality Goals Constituent Water Quality Goal TDS mg L 500 Hardness as CaC03 mg L 100 Alkalinity as CaC03 mg L 100 Sodium mg L 60 to 200 Chloride mg L 250 Raw Water Quality The majority of the raw water delivered to the treatment plant will be seawater although it is expected that some fresh water will be drawn into the beach wells Therefore the pretreatment system should be designed to accommodate a mixture of seawater groundwater and stream discharge Additional investigations i e a pilot pumpin

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g and treatment project possibly with additional groundwater seawater surface water modeling will be required to accurately estimate typical water quality in the intake water and its variability In the absence of this additional information some preliminary estimates of the range of dissolved solids in the feed water

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to the desalination facility can be calculated assuming 10 groundwater 10 surface water and 80 seawater Based on this it is expected that the intake water will have total dissolved solids TDS concentrations ranging from 27,000 to 35,000 mglL desalination Process Reverse Osmosis Figure ES 1 shows the process flowrates assuming the plant is producing

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=10

CHAPTER 1 INTRODUCTION Three agencies the City of Arroyo Grande the City of Grover Beach and the Oceano Community Services District Agencies have come together to participate in the evaluation of a potential drought proof water supply seawater desalination to supplement their existing potable water sources Currently all three Agencies receive water from various sources including the California State Water Project Lopez Lake Reservoir and groundwater from the Arroyo Grande PlainfTri Cities

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=25

y Study Nacimiento Pipeline Extension February 2006 and Water Supply Study desalination February 2006 have been prepared to evaluate various alternatives for potential water supply to meet the deficiency Each report has discussed the potential for seawater desalination to some degree however a more in depth evaluation of the feasibility and cost of such facility was necessary before proceeding with design The February 2006 desalination Study formed the basis for this focused feasibility and funding st

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=25

ope of services Preliminary Design Provide overall preliminary design criteria for all components of the desalination plant including Hydrogeologic Assessment Identify the quantity and quality of available source water for the proposed facility seawater Intake Facility Evaluate alternatives for intake source water methods and provide preliminary design of a seawater beach well gallery intake facility RO Filter System Provide evaluation of the proposed filter system including percent recovery bri

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=26

installation and operation of a seawater desalination plant on the California coast Cost and Funding Update This study will include a life cycle cost analysis for the capital and operations and maintenance costs of the project In addition an approximate schedule and timeframe of major pr

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e and extend offshore Within the area of study there is no indication of a significant subsurface canyon offshore or evidence of major fault barriers that would limit the seaward extent of fresh water outflow or conversely the landward migration of seawater onshore The aquifer in the study area slopes gently offshore Seafloor data would suggest that the Paso Robles formation extends many miles offshore and contains significant volumes of fresh water in storage Evidence of seawater intrusion in the st

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e reduced to levels below the Federal SDWR level of 250 mgtl Table 3 2 lists the finished water quality goals for some of the key water quality constituents 3 3 Raw Water Quality The majority of the raw water delivered to the treatment plant will be seawater although it is expected that some fresh water will be drawn into the beach wells The expected quality of this water is summarized in Table 3 3 SSLOC Desai Funding Study 3 3 October 2008

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seawater but there is a small percentage of fresh water outflow to the ocean that is captured by the intake well about 10 percent Also noted was the possibility that locating the intake structures near points of stream discharge at the ocean such as Arroyo

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Grande Creek could significantly affect water quality stability Therefore the pretreatment system should be designed to accommodate a mixture of seawater groundwater and stream discharge Additional investigations i e a pilot pumping and treatment project possibly with additional groundwater seawater surface water modeling will be required to accurately estimate typical water quality in the intake wa

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=41

ter and its variability In the absence of this additional information some preliminary estimates of the range of dissolved solids in the feed water to the desalination facility can be calculated assuming 10 groundwater 10 surface water and 80 seawater seawater TDS in nearshore environment 34,500 mg L Groundwater minimum TDS 330 mg L from Grover Beach 2006 Water Quality report Surface water minimum TDS 430 mg L Lopez reservoir City of AG 2006 Water Quality report Intake mixture minimum TDS x

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=41

These algal blooms produce toxins that may enter a seawater desalination facility Of particular interest is domoic acid an organic acid produced by marine diatoms of the genus Pseudo nitzschia Domoic acid accumulates in filter feeding organisms such as clams and mussels The Federal Food and Drug Administrati

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on has determined that domoic acid at levels above 20 parts per million in shellfish tissue can be harmful to humans Washington Department of Fish and Wildlife 2008 In EI Segundo California domoic acid reached levels of 2 Jg l in untreated seawater during times of algal blooms in 2005 lauri 2007 and loveland 2006 In May and June 2007 domoic acid was undetected at a detection limit of 10 Jg l in raw seawater at long Beach California Tseng 2007 While it is not known at what level domoic acid

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in drinking water is harmful to humans and no drinking water standards have been set recent pilot tests have shown that treatment of raw seawater with ultrafiltration followed by reverse osmosis reduced domoic acid from 2 Jg l to less than 0.015 Jg l loveland 2006 This result is consistent with the fact that reverse osmosis removes contaminants down to the ionic range 0.0001 Jm which wil

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=42

ormation of bromate and brominated DBPs Treatment by the RO system will remove the majority of any organic DBP precursors as well as almost all of the bromine 3.4 Treatment Process Assumptions 3 4.1 Pretreatment Approaches Membrane filtration of the seawater is recommended as a pretreatment step ahead of RO membranes to prevent solids from reaching the RO membranes and damaging or destroying them As a pretreatment step membrane filtration is recommended in lieu of conventional filtration because experie

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=42

should also be noted that several utilities are considering two pass RO process layouts to reduce levels of boron in the treated water When using this process caustic soda is added upstream of the first and or second pass depending on site specific seawater quality and treated water quality objectives for pH adjustment High pH is necessary to obtain high boron removal Recently several membrane manufacturers have developed high boron rejection membranes It is expected development efforts related to boro

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=46

ass configuration would be used at the full scale In order to control scaling and fouling chemicals such as acid and or anti scalants are added upstream of the desalination process to allow higher recovery and reduce fouling or scaling rates Typical seawater RO systems do not use acid but often do use antiscalants Because site specific feedwater quality data is not available at this time this evaluation assumes use of anti scalants but not acid for pretreatment 3 5.5 Post Treatment The permeate the des

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=47

aulic losses through piping and valving selection of efficient pumps etc In addition four opportunities could reduce energy consumption significantly These include Reducing RO membrane flux or flow rate per unit area of filter below typical values seawater RO plants typically operate at fluxes of 8 or 9 gallons per square foot of membrane area per day gfd Reducing flux can significantly reduce costs For example Boyle recently provided value engineering services to the Honolulu Water Supply Board re

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=49

garding the design of the Kalaeloa 5 MGD seawater desalting plant The designers initial used a design flux value of 9.5 gfd Boyle calculated that reducing the average flux to 6.1 gfd would increase construction costs by 1,500,000 but save 500,000 per year in O M costs This additional 1,500,000 i

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=49

pressure whereas vertical turbine pumps need to be equipped with variable frequency drives VFO so the pump speed can be adjusted to provide the flow and pressure required 2 Piston pumps operate in the range of 300 RPM whereas centrifugal pumps for seawater RO plants operate at about 3000 RPM 3 The life cycle cost for piston pumps is typically less than for centrifugal pumps 4 Piston pumps are typically at least 15 more efficient than centrifugal pumps 3 8 Treatment Plant Layout The proposed site at th

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uality The use of shallow vertical beach wells and or collector i e vertical shaft with horizontal wells beach wells would eliminate impingement and entrainment of sea life a welldocumented impact of open ocean intake systems because the intake of seawater would occur entirely beneath the substrate and no pressure or flow gradient would result in the open ocean 6 1.4 Geology Soils and Seismicity As described in the CEQA Guidelines a project would normally have a significant geologic effect on the envi

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be considered significant if it would result in the use of large amounts of fuel or energy if it would use fuel or energy in a wasteful manner or if the energy supplier cannot meet the project's energy needs with existing and planned energy capacity seawater desalination is considered to be an energy intensive operation and the project would potentially result in significant cumUlative impacts on global climate change due to greenhouse gas emissions associated with high energy use The production of elec

Oceano_Docs/08_1008_OceanoCSD_other---20081008DesalStudy.pdf#page=62

he Project Description as follows Total production goal reduces to 1,550 AFY 800 AFY Grover Beach 750 AFY Arroyo Grande Raw water intake would reduce from 3,830 AFY to 2,720 AFY Number of beach wells required would reduce from 20 25 to 14 to 17 seawater supply pipeline diameter reduces from 16 diameter to 12 diameter RO building footprint would reduce slightly from 15,000 SF to 14,000 SF Brine storage requirements reduce from 750,000 gallons to 500,000 gallons Product water deliver pipeline woul

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utreach programs required to implement such a program 7 Update alternatives for groundwater recharge and direct reuse of recycled water in light of CD PH guidelines and regulations Include a cursory feasibility analysis of using recycled water for a seawater barrier to allow the additional pumping of fresh water from the groundwater basin for potable supply The study will include recommendations for detailed hydrogeologic studies that may be necessary to fully implement such a groundwater recharge progr

Oceano_Docs/08_1022_OceanoCSD_BoD---20081022BoDMeeting.pdf#page=26

he amount of fresh lake water that must be released from Lopez Dam for environmental protection of steel head and other sensitive species 9 Update overall life cycle costs for the various updated alternatives for turf irrigation groundwater recharge seawater barrier and stream augmentation 10 Provide a technical memorandum summarizing the findings of this updated recycled water study AGENDA ITEM 10 22 2008 8 c

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ection and drinking water treatment Eastern Municipal Water Perris Water Filtration Proposition 50 12 million from District Plant Expansion and SLate Chapter 4b 2006 Department of Health Water Project Pipeline Services Project West Basin Municipal seawater Barrier Water DWR Groundwater 6.5 million Water District Conservation Project Storage Construction Grant 2003 West Basin Municipal Restroom Retrofit Project Proposition 50 294,824 Water District Chapter 7 2005 Otay Water District Recycled Water

Oceano_Docs/09_0422_OceanoCSD_BoD---20090422BoDMeeting.pdf#page=34

0 and are to be divided between the Northern Cities according to their share of the groundwater As a result of the findings in the report it was determined that additional water quality testing should be done immediately to determine if there is any seawater intrusion into the basin so that immediate remedial steps might be taken if such is the case The additional water quality monitoring will cost about 13,000 Again these costs are to be divided between the Northern Cities according to their share of

Oceano_Docs/09_0513_OceanoCSD_BoD---20090513BoDMeeting.pdf#page=83

lexible and rapid response to changing groundwater conditions Accordingly the first 2009 scope is submitted herein in detail while the scopes of work for subsequent years remain open The 2009 effort would address the high priority issue of potential seawater intrusion with regular sentry well sampling and water quality analysis The 2009 effort also should include an evaluation of the hydrogeologic setting of the NCMA and assessment of the monitoring network in its geologic context This would allow impro

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=44

ved interpretation of groundwater levels storage changes and seawater intrusion potential and support proactive management of NCMA groundwater The 2009 effort would provide specific recommendations possibly including field work and development of a numerical model that could be applied to a variety of management scena

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=44

equipment blank sample and one or two duplicate samples also will be taken for quality control purposes Analyze all samples for general mineral constituents plus bromide iodide nitrate and total nitrogen to allow diagnostic evaluation for potential seawater intrusion Sampling also will include measurement of pH temperature EC and turbidity to allow evaluation of the accuracy of the analytical data Water levels will be measured in each well prior to sampling We recommend use of subcontractors for the sa

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=45

mpling procedures 1.3 Evaluate sentry well data e g constituent trends Schoeller Piper Brine plots Our senior geochemist Dr William Motzer will direct the evaluation of the sampling data to ensure its accuracy and to detect changes in the potential seawater intrusion The new sentry well analytical data will be entered into an Excel workbook along with historical sampling and other representative water quality data e g seawater and local groundwater The data will be examined for accuracy and evaluated

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nd other plots 1.4 Prepare quarterly technical memoranda summarizing the sentry wells water quality data These brief technical memoranda will present the most recent water quality and water level sampling data and provide timely updates on potential seawater intrusion For costing purposes we assume these technical memoranda will be delivered electronically Deliverables Three Monitoring Memoranda Northern Cities 3 Todd Engineers

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=45

cumentation of Hydrogeology This task provides an evaluation of the hydrogeologic setting of the NCMA and assessment of the monitoring network in its geologic context This will support improved interpretation and management of groundwater levels and seawater intrusion potential 2.1 Document the hydrogeologic setting This will include documentation of aquifer and aquitard zones aquifer properties boundaries and to the extent possible the bottom of the NCMA portion of the groundwater basin and offshore ge

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=46

K groundwater level patterns in relation to rainfall and municipal pumping patterns Eastwest groundwater level transects from the coast inland also will be prepared to monitor seaward landward gradients 2.6 Evaluate hydraulic heads needed to control seawater Identify and recommend basin management objectives BMOs relative to groundwater levels in sentry wells These objectives would define groundwater levels above mean sea level in sentry wells to establish seaward groundwater gradients and flow in mea

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sured zones and to thereby minimize the potential for seawater intrusion The BMOs would provide both objectives for groundwater levels and thresholds plus specific actions e g reduction in pumping if thresholds are exceeded 2.7 Identify key data gaps and provide recommendations for additional work Recommendati

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=47

aquifer properties can be perfonned in existing wells Recommendations also may involve development of a numerical groundwater model to assist the Northern Cities in managing groundwater pumping to control groundwater levels along the coast and repel seawater intrusion 2.8 Prepare a draft and final technical report summarizing the hydrogeologic setting and groundwater conditions as documented in Tasks 2 and 3 Prepare a draft technical report for submittal to the Northern Cities The final report will addr

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=47

and for the Annual Report William Motzer Ph D P G Project Geochemist Dr Motzer Senior Geochemist will provide review and evaluation of the sentry well sampling and related water quality data to ensure its accuracy and utility in detecting potential seawater intrusion Northern Cities 8 Todd Engineers

Oceano_Docs/09_0722_OceanoCSD_other---2009_07_22_BOARD_MEETING.pdf#page=52

desalination Facilities o Marin Municipal Water District MMWD published an engineering report from 2007 on their website http www marinwater 0rg documents EngRepDesal Engineering Rep 0 12607 Rev ES4 pdf detailing the results of a pilot study on a seawater desalination facility to treat water from the Northern San Francisco Bay The report includes preliminary cost estimates for four construction alternatives Case A D for a full scale desalination facility Table 3 summarizes the total water cost estim

Oceano_Docs/09_0812_OceanoCSD_other---2009_08_12_Board_Meeting_Agenda_Packet.pdf#page=44

S42OOO OOO Annualized Capital Cost S1,471,260 51,471,260 52,734,200 S2,734,2OO Tolal Project Annual Costs 512 895724 513 163 871 515881275 521 447756 To al Water Cos 5 ptr AF 52433 52484 52996 52023 o Tampa Bay Water district has a fully operational seawater desalination facility in their districl completed at the end of2007 The total conslruction cost was estimated at 158,000,000 with an estimated production capacity of28,000 MY The cost of water produced at the plant is currently 1,100 per AF 3.38

Oceano_Docs/09_0812_OceanoCSD_other---2009_08_12_Board_Meeting_Agenda_Packet.pdf#page=45

2005 indicates that water budget projections for the Central Coast region show a deficit in overall water storage Because the majority of potable water on the Central Coast is provided by groundwater overpumping of the groundwater basins is creating seawater intrusion problems region wide Table 4 1 in the DWR Report shows the quantity of water entering the region by groundwater pumping surface water extractions or imported water supply is less than the water leaving the region on the order of 1,500 tho

Oceano_Docs/09_0909_OceanoCSD_BoD---20090909BoardofDirectors.pdf#page=40

supply sources including recycling groundwater recovery water marketing and desalination to help meet future water demands Local hydrogeologists familiar with the groundwater basins in the study area indicate that there has been no indication of seawater intrusion from samples taken in the study area It should be noted that high TDS has been discovered in upper aquifers but that groundwater seems to be of good quality below 50 feet As stated earlier strict management of the groundwater basins will h

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elp prevent seawater intrusion problems Since the South San Luis Obispo County Agencies already operate under an existing Groundwater Management Agreement that ensures pumping allocations are within the safe yield of the groundwater basin problems with seawater intrusio

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n should not be an issue in the future Substituting recycled water for agricultural and municipal demands can help ensure that seawater intrusion will be minimized or avoided in future years The quality of the water from wells through out the area is generally considered acceptable for domestic and agricultural uses The quality of the Nipomo Mesa HSA is generally of a better quality

Oceano_Docs/09_0909_OceanoCSD_BoD---20090909BoardofDirectors.pdf#page=41

delivery of allocation without drought buffer program The local groundwater supply is considered relatively reliable so long as area purveyors continue with cooperative means of managing the groundwater basin to prevent overdraft and advancement of seawater intrusion Inter Agency Agreements It is possible that neighboring water purveyors can provide temporary water surplus supplies to one another during shortfalls However it is noted that both the Cities of Arroyo Grande and Grover Beach are currently

Oceano_Docs/09_0909_OceanoCSD_BoD---20090909BoardofDirectors.pdf#page=44

et below mean sea level It was noted that the deepest groundwater elevations were taken in active well fields and may be lower than true static conditions The area below mean sea level in October 2008 extended to the coast indicating a potential for seawater intrusion The Water Plan Update paragraph provides useful regional context but the subsequent first full paragraph of page 4 4 should be clarified and updated Historical sampling and analysis of four dedicated sentry wells along the NCMA coast have

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shown no clear indication of seawater intrusion A shallow sentry well in the northwestern corner of the basin historically has shown high sodium and chloride concentrations that have been described by the California Department of Water Resources as an artifact of local geology Recognizi

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ng the potential for seawater intrusion and the benefits of monitoring the four Northern Cities are currently engaged in cleaning out and sampling the sentry wells The sentence that adherence to the Gentlemen's Agreement allocations should prevent seawater intrusion is too strong and should be deleted The Todd Engineers April 2007 Water Balance Study far the Northern Cities Area showed that the 200 AFY allocation for subsurface outflow to prevent seawater intrusion is too low Moreover the allocation a

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generally favorable evaluation of the state of the groundwater basin It concluded that available supplies exceeded total urban demand and that estimated subsurface outflow to the ocean of 2,700 3,000 AFY was maintained which is helpful in preventing seawater intrusion Although the groundwater elevations at several of the listed wells were near or below sea level during 2007 and 2008 the report concluded that the saltwater interface appeared to be offshore and that there was no indication of seawater int

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rusion Several measures were recommended to avoid seawater intrusion including a water quality sampling program and mutual strategies among the Northern Cities to reduce coasta l pumping and increase use of other available water supplies However some of the data seemed to indicate a pending problem First an

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ons at sentry well ports 30F3 and 30N2 were 5 ⸀㈀㈀ and 1.88 feet msl respectively in the fall Although the groundwater elevation for sentry well port 30F3 was measured at or below mean sea level mUltiple times between 1986 and 1998 with no apparent seawater intrusion the groundwater elevation at sentry well port 30N2 had never been measured below sea level throughout the 40 year period of record Taken together these trends signaled a condition of short term overdraft which left the basin vulnerable to

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seawater intrusion if dry conditions persisted and high pumping rates were sustained October 20 2009 Page 2 of 5 C Dat WSC 3.0 Prnjects Five Cities Tuk 1 Peer Review Df 8 2009 Sentry Well 1.0 Oeliverab les 091020 Peer Review TM Or ft d c

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historic samples chloride concentrations in 30N02 and 30N03 increased dramatically between May and August of 2009 The time concentration plots for chloride and Schoeller and Piper diagrams for sentry well ports 30N02 and 30N03 are clear evidence of seawater intrusion Review of Recommended Scope of Work The October 2009 Proposal includes ongoing monitoring activities at the sentry wells preparation of the required NCMA annual report review of the NMMA annual report and general coordination Task 1 Sentry

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ence calls etc General Basin Management Recommendations The groundwater basin underlying the NCMA is a critical component of the Northern Cities overall water supply and is an extremely important and valuable asset to the region With the evidence of seawater intrusion presented in the August 2009 Monitoring Memo and the possibility of continued drought conditions decisive action is required to preserve this critical resource Based on a preliminary review of the documents listed above WSC recommends prio

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lement a plan to expand groundwater recharge Plan components could include expanding and or improving existing percolation basins construction of new percolation basins evaluating recycled water recharge opportunities considering opportunities for a seawater intrusion barrier etc 6 Develop a regional conjunctive use plan The goal of the plan would be to maximize the beneficial use of each of the Northern Cities water supplies in a way that is cost effective and sustainable long term The plan would estab

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model would become a critical tool for improving basin management by allowing the Northern Cities to evaluate various recharge and pumping scenarios optimize conjunctive use strategies evaluate well Siting and or pumping regimes evaluate options for seawater intrusion barriers etc October 20 2009 Page 5 of 5 C Dat WSC 3.0 ProJ cts Flve Cltles Task 1 Peer RevIew of 8 2009 Sentry WeU 7.0 Delive rables 091020 Peer ReView TM Draft docx

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e was data taken in October which is the a low time DCE Wallace stated the sea water intrusion wedge between the saltwater fresh water interface is very discreet not a big zone and it was misrepresented in size The zone is compact as it takes place seawater and fresh water are different and it is heavier and it creeps in and which is why we see a large jump in the chlorides Dir Lucey asked if the recommendations would change after learning the Brisco Turnout can pump to capacity and can we get all of t

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ange Average Range Average Potential Source of Contamination Aluminum ppb 200 ND 100 50 ND Naturally present in the environment and residue from water treatment processes Chloride ppm 500 31 147 89 35 42 38.5 Runoff leaching from natural deposits seawater influence Color CU 15 ND 3 1.5 3 10 6.5 Naturally occurring organic materials Corrosivity LI Natural or industrially influenced Noncorrosive ND ND ⸀㌀ 1.22 Noncorrosive balance of hydrogen carbon and oxygen 0.76 in the water affected by temperatu

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re and other factors Odor Threshold 3 1 6 3.5 1 3 2 Naturally occurring organic moterials Specific Conductance micromhos 1600 231 786 508.5 960 1000 980 Runoff leaching from natural deposits seawater influence Sulfate ppm 500 63 103 83 170 190 180 Runoff leaching from natural deposits industrial wastes Turbidity NTU 5 ⸀　㐀 1.4 ⸀㜀㈀ ⸀㄀ 3.6 1.85 Soil runoff Presence of colloidal and or suspended matter Total Dissolved Solids ppm 1000 130 493 311.

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of Suriace Water Well Water Contaminants without a Drinking Water Standard Contaminant reporting units Range Average Range Average Potential Source of Contamination Alkal nityas CaCO ppm 52 250 151 270 370 320 Runoff leaching from natural deposits seawater influence Calcium ppm 30 76 53 110 130 120 Runoff leaching from natural depOSits seawater influence Hardness ppm 60 370 215 460 530 495 Generally found in ground and surface water MagneSium ppm 17 34 25.5 49 58 53 ⸀㔀 Runoff leaching from natural

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deposits seawater influence pH 7.5 9 8.25 7.5 7.6 7.55 Runoff leach ing from natural deposits seawater influence Sodium ppm 38 77 57.5 36 47 41.5 Runoff leaching from natural deposits seawater influence Vanadium ppb ND ND ND 22 II Runoff leaching from natural deposits seawater influence Table 6 Sampling Results ShOWing the Detection of Lead and Copper Lead Capper to be com No of 90th No Sites AL MCLG Typical Source of Contaminant plet

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clined to direct staff to proceed with a more specific analysis and discussions with other agencies primarily the City of Arroyo Grande One major factor is the District's future ability to pump groundwater and how that might affect the potential for seawater intrusion To simplify this current analysis it was assumed that the District would be able to continue to pump groundwater within the limits of the Gentlemen's Agreement to make up the difference in available supply from State Water Lopez Water and

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Demand Year Population Demand Demand gpcd AFY 2003 8,117 100 910 2004 8,215 103 953 2005 8,324 100 933 2006 8,422 94 885 2007 8,519 97 925 2008 8617 97 934 Average 8,369 98 923 GROUNDWATER In order to reduce groundwater pumpage to protecl against seawater intrusion the District would need to rely more on its Lopez and state water supplies To increase the reliability of its state water deliveries at some point the District will also need to purchase buffer water from the County's excess state water a

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The cost of reducing groundwater pumpage to protect against seawater intrusion is being discussed with all the other affected agencies Pismo Beach Arroyo Grande and Grover Beach in the Northern Cities Management Area NCMA Therefore the District's cost to purchase buffer water may be shared with these other agencies

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ndwater pumpage and secondly the appropriate cost sharing between agencies During this past year samples taken at the sentry well located near the Pier Avenue entrance to the State Park in Oceano displayed characteristics indicating the beginning of seawater intrusion However with the recent rains this season groundwater levels have risen and the immediate threat of seawater intrusion has been somewhat mitigated but to what extent is not precisely known at this time On going monitoring will help clarify

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if no other variables contradict the analysis No estimates of sunk costs were included in this analysis Any desire to capture previous investments in the Lopez entitlement would be subject to negotiations Groundwater pumpage and the potential for seawater intrusion must be considered before any agreement is reached to sell a portion of the District's permanent Lopez entitlement Staff will receive general Board direction and proceed with additional more detailed analysis and hold discussions with the

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storic information and data sources GIS coverage and establish the plan for obtaining and compiling the data during Task 1.5 We will recommend alternative ways to visualize and interpret the data using examples from other area that we have worked on seawater intrusion issues including the Salinas and Pajaro Valleys and facilitate a discussion and receive input and guidance from the client on what should be included in the annual report We will use this input to prepare the draft outline for final review

Oceano_Docs/10_1013_OceanoCSD_BoD_Packet---SKMBT_C45110100803370.pdf#page=65

he method for the monitoring years beyond 2010 Threats to Water Supply The April 2010 Annual Report identifies several threats to NCMA water supply State wide and local drought Climate change Reduction in amount and reliability of SWP deliveries seawater intrusion A number of factors can affect availability and quality of water suppl ies In order to understand threats all factors must be considered Therefo re based on our extensive experience with Central Coast area wide Integrated Regional water M

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of resignation to be received fonm President Vem Dahl Prior to Friday December 3rd 2010 j Discussion Sale of Water to Nipomo See if Nipomo is interested in the purchase of groundwater k Discussion conclusion to letter initiated 11 24 2009 potential seawater intrusion Letter of protest from new Board Member Y lAgendas BOAJWME TlNG AGf NDASI20JOlj 1 0 20IOWovember 10 2010Agenda doc 2

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iams Oceano read a prepared letter regarding rate increase Wednesday Jeff Edwards Los Osos urged the Board of Directors to take a look at the big picture regarding of water 4 Board Member Comment Director Lucey provided a handout about the potential seawater intrusion Northern Cities Management Area and the Initial Study and Proposed Negative Declaration dated September 24 2010 Director Lucey requested that the handouts be available for the publ ic 5 Review and Approval of Minutes a October 13,2010 Aft

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Oceano OCEANO COMMUNITY SERVICES DISTRICT BOARD OF DIRECTORS MEETING November 10 2010 k Discussion conclusion to letter initiated 11 24 2009 potential seawater intrusion Aft r public comment Board discussion a motion by Director Hill second by Director Angello and the following roll call vote Wednesday Ayes Director Hill Director Angello VP Dean Director Lucey President Dahl Na s None the following motion

Oceano_Docs/10_1208_OceanoCSD_BoD_Packet---SKMBT_C45110120523140.pdf#page=9

was adopted to support the sending out a letter on the next mail date regarding the evidence against potential seawater intrusion with the modification to the fourth paragraph suggested by VP Dean by adding the sentence also Oceano Community Services District uniiateraUy stopped pumping ground water at that time in response to the threat 8 Utility Items a Will Serve

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Oceano OCEANO COMMUNITY SERVICES DISTRICT BOARD OF DIRECTORS MEETING November 10 2010 k Discussion conclusion to letter initiated 11 24 2009 potential seawater intrusion After public comment Board discussion a motion by Director Hill second by Director Angello and the following roll call vote Wednesday Ayes Director Hill Director Angello VP Dean Director Lucey President Dahl Nays None the following motion

Oceano_Docs/11_0112_OceanoCSD_BoD---01_12_2011_bod_meeting.pdf#page=9

was adopted to support the sending out a letter on the next mail date regarding the evidence against potential seawater intrusion with the modification to the fourth paragraph suggested by VP Dean by adding the sentence also Oceano Community Services District unilaterally stopped pumping ground water at that time in response to the threat 8 Utility Items a Will Serv

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llocate water supply in the basin based on need DISADVANTAGES Purchase of OCSD water does not increase the overall supply of water to the water basin and purchase of State water may result in increased usage of groundwater by OCSD which could impact seawater intrusion concerns However the amounts discussed are minimal and should have little impact When added to other cost increases and revenue reductions it will also have an impact on rates However it would be less than other options identified to meet

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The following are links to all the copies of board Minutes, Agendas, Board packets (BP) and Audio of Oceao CSD meetings on this site.

The first numbers listed are the date in YEAR_MMDD format.

Oceano doucments:

Nipomo Water

Documents and informatin realted to water in Nipomo.

Northern Cities Documents

Ocenao CSD board documents:

The following is the result of using acrobat to OCR all the online Oceano board agendas and then a search those files to find the text around and the page of the word "seawater" and create a link to the document:

The following are links to all the copies of board Minutes, Agendas, Board packets (BP) and Audio of Oceao CSD meetings on this site.

The first numbers listed are the date in YEAR_MMDD format.

Oceano doucments: