The desalination unit at the Gaviota Oil and Gas Processing Plant began operation in 1987 and has design specifications to last 25 years. The RO unit, which has the capacity to produce 460 AF/yr (about 450,000 gpd) of water, uses power from an onsite cogeneration plant to produce 100% of the processing plant's current freshwater needs (about 153,000 gpd). Several grades of water are produced, with the least pure at about 500 ppm tds and the most pure at about 50 ppm tds. A portion of product water is subsequently treated by ion exchange to less than 1 ppm tds for use as boiler feed water. Product recovery is about 35%. Energy use is approximately 15,000 kWh/AF. The unit occupies an area of about 90 feet by 130 feet, and the tallest component is about 15 feet high. The average cost to produce the water is about $4,000/AF. This cost is relatively high for the following reasons: the unit is small, so there are not economies of scale; the unit does not use energy recovery; a new and expensive seawater intake system was built; and Chevron constructed the unit to meet the same specifications with respect to quality of construction and safety as the rest of the processing plant. (Source: pers. comm. with Bob Burelson, Chevron, 1991, 1993.)
The Environmental Impact Report/Statement (EIR/S) prepared for the project found that the impacts of desalination discharges would not be significant as long the conditions in Chevron's NPDES permit issued by the State RWQCB were followed. Chevron originally discharged waste brine directly to the ocean through an outfall terminating in the surf zone at a water depth of 10-15 feet. In May 1993, Chevron began discharging combined effluent from the processing plant (treated produced water) and the RO unit (brine) through a 5,200-foot-long produced water outfall at a 100 foot water depth. The combined discharge is authorized under a modified RWQCB NPDES permit.
In April 1985, the Coastal Commission granted a coastal development permit (CDP) to Chevron for construction of two pipelines and one produced water outfall for the oil and gas processing plant (No. E-85-2). In July 1986, the Coastal Commission approved with conditions an amendment to this CDP to allow for the addition of the offshore portions of the desalination unit-two seawater intake lines and one brine discharge line (No. E-85-2-A). The conditions imposed in the amendment were: 1) the conditions of CDP No. E-85-2 will remain in effect; 2) Chevron will obtain a NPDES permit from the RWQCB for the discharges; and 3) the development will not interfere with rights of access.
The City of Morro Bay has constructed a temporary emergency RO desalination plant that is not currently in operation. Product water from the 0.6 MGD plant would replace a portion of the City's water supply as needed due to reduced quantity and/or quality of the City's groundwater supplies. The City was able to build the plant without prior preparation of an EIR by existence of a state of emergency because of drought. In April 1993, the Morro Bay City Council certified a project EIR that includes analysis of continuous operation of a 1.2 MGD plant to provide a permanent supplemental water supply. When operating, the plant draws feedwater from six seawater intake wells. The plant may also use brackish water on the Morro Creek aquifer as an alternative source of feedwater. Product recovery is about 40% for seawater and 65% for brackish water. Electricity use for the plant is about 8,900 kWh/AF for seawater. The product water would cost the city $1,750/AF based upon a seawater source. (Source: pers. comm. with Bill Boucher, City of Morro Bay, 1991, 1993.)
In January 1991, the Coastal Commission granted the City a permit waiver (No. 4-90-55-DM) for the drilling of test wells to determine desalination source water quality. In June 1991, the City approved an Emergency CDP for the portion of the desalination plant within the City's permit jurisdiction. In September 1991, the Commission approved with conditions a CDP (No. 4-91-37) for the portions of the plant within the Commission's original permit jurisdiction; this CDP authorized the discharge of brine through the Morro Bay/Cayucos Wastewater Treatment Facility outfall. In January 1992, one month after the U.S. Environmental Protection Agency objected to the use of the municipal outfall for brine disposal purposes, the Commission revoked CDP No. 4-91-37 at the request of the Cayucos Sanitary District. In February 1992, the City approved a CDP for a revised project that provided for the discharge of brine through the PG&E Morro Bay Power Plant cooling water outfall. The Commission granted a CDP (No. 4-92-01) for the revised project in April 1992 and adopted revised findings in June 1992. CDP No. 4-92-01 contains the following thirteen special conditions:
1) the permit shall apply only during a period of Level 5 Water Emergency conditions as declared by the City Council in the City of Morro Bay;
2) the permit shall be limited to eighteen months from the date of approval (at the end of this period, a regular CDP for continued operation would be needed to retain the plant);
3) acceptance of the permit shall result in no net increase to the City's existing yearly water supply (desalination product water shall be used only to replace water that is unavailable to the City because of decreases in water supplies due to quantity or quality standards sufficient to create a Level 5 "Emergency Water Supply Condition");
4) the City shall not discharge any seawater brine or brackish wastewater through the Morro Bay/Cayucus Wastewater Treatment Facility or discharge outfall;
5) during operation, the City shall submit monthly reports to the Executive Director (E.D.) on the effects of seawater intake on the City's aquifer and groundwater wells;
6) the City shall submit to the E.D. a final agreement between the City and PG&E to allow the City to use PG&E's outfall and easement area for desalination plant discharges;
7) the City shall discharge all desalination brine and wastes through the PG&E outfall;
8) the City shall submit to the E.D. any marine quality/biological monitoring studies and/or other data required by the RWQCB as conditions of its NPDES permit;
9) specified mitigation measures shall be employed to minimize impacts to the sand dune plant community from installation of the seawater feed and brine discharge pipelines;
10) specified mitigation measures shall be employed to minimize alteration of Morro Creek habitat from installation of the seawater feed and brine discharge pipelines;
11) the City shall submit for review and approval by the E.D. a landscape and irrigation plan;
12) the City shall submit for review and approval by the E.D. a construction schedule, traffic and public access plan/defined construction staging area that minimizes disruption to public accessways and that provides for continued recreational use of these areas; and
13) the City shall process and approve an interim CDP for the desalination plant and lines within the City's jurisdiction that is consistent with CDP No. 4-92-01.
As specified in Special Condition 1, the City's desalination plant is not operating at this time, since a Level 5 Emergency Water Supply Condition is not currently in effect.
In March 1992, the City of Santa Barbara began operation of a temporary seawater RO desalination plant. After operating for several months to allow testing of components, the plant was placed on long-term standby status due to the increased availability of reservoir supplies (which were replenished during the Winter 1992/93 rains) and reduced demand from water customers. The plant, which has a capacity of 7,500 AF/yr, is capable of providing 21% of the average pre-drought water needs of the City of Santa Barbara, Goleta, and Montecito. The cost of the water to the City is projected to be $1,918/AF. Under the City's contract for the plant, capital costs must be paid for in five years. If the plant continues to operate beyond that time, the cost of the water will be reduced.
The plant is located on 2.1 acres (including pump station and chemical treatment area) in an urban area of Santa Barbara. Product water quality is projected to be between 284 and 400 ppm tds (the operational value during plant testing was approximately 300 ppm tds). Product water recovery is 45%. Electricity use for the plant is about 6,600 kWh/AF. The desalination plant was designed to take feedwater from two existing ocean intakes and to discharge brine through an existing outfall. Intake velocity is 3 cm/s or less (local ocean currents flow at a rate of 0-40 cm/s), and the intake screen has 3/8-inch spacing, thus excluding most marine species (although small invertebrates and larval and other microscopic organisms can still be entrained). The plant will discharge about 10 MGD waste brine and backwash that will be mixed with effluent from the El Estero Wastewater Treatment Plant. The combined discharge will have a salinity level of 26,000 to 55,000 ppm. The plant will generate 1.7 to 5.1 cubic yards/day of nonhazardous solid waste. (Source: pers. comm. with Dale Brown, City of Santa Barbara, 1991, 1993.)
In March 1991, the City's Planning Commission approved a CDP for the onshore portion of the temporary desalination plant. In May 1991, the Coastal Commission approved with conditions a CDP (No. 4-91-18) for installation of a liner sleeve in an existing abandoned ocean outfall line and addition of ocean intake structures and auxiliary facilities to service a temporary five-year facility with a production capacity of 10,000 AF/yr. CDP No. 4-91-18 contains the following six special conditions:
1) the permit will apply for a period of five years only;
2 the applicant shall submit to the Executive Director for review and approval a pre-construction baseline monitoring program and an ongoing monitoring program, and if monitoring results indicate any adverse effects on the marine environment, the applicant must apply to the RWQCB for an amendment to the NPDES permit;
3 the applicant must obtain an NPDES permit prior to operation;
4) the applicant shall submit a plan for reducing impacts of construction on recreation and public access prior to operation, shall enclose the beach excavation area within a fence for public safety, and shall locate the excavation area to minimize disruption of lateral beach access;
5) the applicant shall mark the subsurface intake structures with a U.S. Coast Guard-approved lighted navigational buoy and shall notice the project in the "Notice to Mariners"; and
6) the applicant shall submit to the Executive Director for review and approval a plan for monitoring, evaluating and mitigating impacts to archaeological resources.
In June 1991, the citizens of the City of Santa Barbara voted for development of a permanent desalination facility. To extend the life of the project beyond the five-year limit of CDP No. 4-91-18, the City will have to complete additional environmental review and permitting and receive another Coastal Commission permit. The additional environmental review is currently underway.
The California Department of Parks and Recreation (DPR), San Simeon Region has installed, but is not currently operating, an RO plant at the Hearst San Simeon State Historical Monument visitor center. The unit would provide sufficient water supplies for onsite uses during the summer months and would replace the former practice of trucking-in water during the summer. The capacity of the unit is 40,000 gpd, but the plant would operate only 16 hours/day from May through September for a total output of about 26,000 gpd. The DPR is leasing the unit, which was renovated and transported to the site, from the State Department of Water Resources (DWR) for a ten-year period.
Seawater would be obtained from an intake pipe located 650 feet offshore. Product water recovery would range from 28-40%, depending on seawater temperature, operating pressure, and membrane condition. The product water would contain 200 to 400 ppm tds and the concentration of the brine discharge would range from 45,000 to 63,000 ppm tds. Discharges to the ocean would not contain chemical additives or treatment aids, as chemicals used during the desalination process would be treated and discharged into a sewer line or disposed of at a treatment facility. (Source: pers. comm. with David Donahue, DPR, 1991; Robert Kinney, DPR, 1993.)
In March 1991, the County of San Luis Obispo granted a permit for the onshore portion of the project. In May 1991, the Coastal Commission approved with conditions a CDP (No. 4-90-40) for installation of a submerged pump, 650 feet of intake line and 335 feet of discharge line for the desalination plant. CDP No. 4-90-40 contains the following two special conditions:
1) The permit is valid for two years from the date of Commission action. As a filing requirement for a new permit application for a desalination plant, the applicant shall submit a water management plant for both the Hearst San Simeon State Historical Monument and the San Simeon State Beach, identifying current water uses and identifying methods to reduce water consumption. The goal of this plan will be to reduce water consumption so as to reduce or eliminate the need to desalinate ocean water.
2) The pipelines crossing the beach shall remain covered at all times during the two-year process (by either sand or a wooden covering).
The DPR is in the process of applying to the Commission for a CDP amendment to allow for operation of the plant on a standby status (i.e., during drought conditions) beyond the two-year period authorized in Special Condition 1. The California Department of Fish and Game (DFG) determined that plant operations would not significantly impact fish or wildlife.
The Monterey Bay Aquarium has begun construction of an onsite RO unit to provide water for some of the aquarium's non-potable water needs (i.e., toilets), thus reducing the current demand for the City of Monterey's water. The desalination unit would have separate pipes and connections from the City's water supply and would have no provisions for trucked-in water if the unit breaks down. When completed, the unit will produce a maximum of 43,000 gpd with average production about 21,500 gpd. The unit would process water prefiltered by the existing seawater system that supplies the aquarium exhibit and research tanks. The quality of the water produced will be about 400 ppm tds. Although the water would be treated to potable water standards, it would not be classified as potable. Waste brine would be blended with seawater used in the aquarium and discharged through an existing outfall. The RWQCB determined that the desalination discharge would not require an NPDES permit based on the relatively small increase in flow rate (as proposed, the rate of discharge will increase from 15 gallons per minute (gpm) to about 51 gpm) and the insignificant amount of pollutants in the discharge. The cost to produce the water would be about $1,800/AF ($5.53/1,000 gals). (Source: pers. comm. with John Christensen, Monterey Bay Aquarium, 1991, 1993.)
In 1989, Monterey County wrote an ordinance that requires public ownership of desalination plants and requires that each plant have a dual system, where one side is held in reserve in case of a breakdown in the other side.[1] In January 1991, the county code was amended to allow for privately run desalination plants, as long as product water is used only onsite. The amendment was written to allow for the Monterey Bay Aquarium project and a privately run inland plant. In May 1991, the Monterey County Department of Health issued a permit to construct the desalination facility. In February 1992, the Coastal Commission approved a CDP amendment (No. 3-90-40-A2) for the remodeling of the Aquarium, including installation of a desalination unit and a 25,000 gallon storage reservoir. The amendment contains one condition related to desalination. Special Condition 2 states: "In the event that the building remodel is complete before the desalination system is operating, prior to any hookup of new fixtures to the public water system the permittee shall submit to the Executive Director for review written authorization from the Monterey Peninsula Water Management District for service to the added fixtures."
In 1985, Sand City approved the Sterling Center development. The approval was appealed to the Coastal Commission which, after finding that the approval raised a substantial issue with the City's certified Local Coastal Program (LCP), denied the project in April 1986. (The Commission found in part that the project's proposed water use demand exceeded its LCP water allocation for the site.) The City subsequently approved a scaled-down project. However, this approval was nullified by the Monterey County Superior Court which ruled that substantial changes had been made to the project that required the preparation and distribution for public review of a revised Supplemental EIR.
After complying with the Court's decision, Sand City approved a revised version of the scaled-down project in November 1990. This project also exceeded the LCP water use demand allocation. To mitigate this impact, the applicant proposed to construct an onsite RO desalination facility with a capacity of 20 AF/yr (about 20,000 gpd). Feedwater for the plant would be taken from a groundwater well. The City also required that the applicant build a pilot desalination plant and provide testing and monitoring of the plant's discharges by a phytoplankton biologist to insure that adverse impacts to marine life are not created. The new permit was also appealed to the Commission, which found substantial issue on the appeal in February 1991 (Appeal No. A-3-SNC-90-127). In April 1991, the Commission approved the development with a condition requiring that the applicant submit prior to construction of the desalination facility any approvals necessary to permit operation in the Monterey Bay area, including a RWQCB-approved NPDES permit for discharges of desalination wastes. The desalination facility has not been constructed to date.
Southern California Edison (SCE) and Whitehawk Catalina, Inc. completed construction of a 132,000 gpd RO plant on Santa Catalina Island in June 1991. The plant produces 25 to 30% of the Island's water supply, including the potable water supply for the Hamilton Cove condominium development. The desalination plant is located adjacent to SCE's Pebbly Beach Generating Station, and brine is discharged through the station's existing cooling water outfall. Feedwater is taken from two seawater wells. Product recovery is about 27%. The size of the plant is about 2,100 square feet. The cost of the water produced is about $2,000/AF ($6/1,000 gals). In September 1989, the Coastal Commission approved a CDP (No. E-89-3) for construction of the plant with one condition requiring that SCE and Whitehawk Catalina obtain an NPDES permit prior to plant operation.
In addition to onshore desalination facilities, a number of oil and gas structures on the Outer Continental Shelf (OCS) have desalination units that produce water for onsite uses. For example, RO units are located on Platforms Habitat, Henry, Hillhouse, and Hondo; distillation units are located on Platforms Gail, Grace, Harvest, Hermosa, and Hidalgo, and on Exxon's Offshore Storage and Treatment (OS&T) vessel. [2] Each unit produces 12,000 to 17,000 gpd, except for the units on Hillhouse and Henry, which produce 2,000 to 2,900 gpd and the unit on Habitat which produces 5,000 gpd of potable water and 6,000 gpd of "demineralizer feedwater" (used for NOx abatement in the platform's gas turbine). Platforms Gail, Harvest, Hermosa, and Hidalgo have two units each. The RO units cost about $80,000, and the distillation units cost about $180,000. No desalination units are located on platforms in state waters; fresh water is supplied through pipelines from shore.
Status of Other Proposed Coastal Desalination Projects
The ACWD is currently updating its 25-Year Water Resources Master Plan and will use the above results for comparison against other water resource alternatives to improve its future water supply reliability. According to the ACWD, desalination of brackish groundwater has the greatest potential at this time. (Source: pers. comm. with James Beard, ACWD, 1993.)
Although an EIR was completed for a permanent desalination facility, the MMWD Board of Directors voted in July 1991 not to build a permanent plant. [3] The desalination plant proposal was for a two-pass RO plant that produced water with 100-200 ppm tds. The plant capacity was intended to be about 5 MGD initially and 10 MGD ultimately. Recovery was estimated to be about 47%. The cost to produce the water was estimated at $1,600-1,700/AF. Energy use by the plant was estimated at 4,900 kWh/AF. The proposed project site was 7.5 acres. The plant would have taken seawater from a newly constructed intake and discharged about 6 MGD of liquid wastes to San Francisco Bay through the Central Marin Sanitation Agency's outfall. In addition, about 11 tons per day of non-toxic solid wastes would have been disposed of in a landfill. The MMWD is not planning to renew the proposal for a desalination plant at this time. (Source: pers. comm. with Robert Castle, MMWD, 1991, 1993.)
ENDNOTES
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