Loading...
HomeMy WebLinkAbout01/30/2003, BUS 3 - GROUNDWATER DEVELOPMENT PROJECT council Jan. .30, 2003 acEnba Repoizt CITY OF SAN LUIS OBISPO FROM: John Moss,Utilities Directo -� Prepared By: Gary W.Henderson,Water Ivision Manager SUBJECT: Groundwater Development Project CAO RECOMMENDATION Direct staff to prepare a request for proposals for the Groundwater Development Project, following the exploratory well drilling project, and return to Council for approval of the scope of work. DISCUSSION The City of San Luis Obispo has been pursuing the opportunity to increase the City's available water resources by increasing the use of groundwater for a number of years. Several studies have been undertaken to determine the additional yield from the groundwater basin as well as the potential impacts associated with increased withdrawals. While the studies indicated that significant increases in groundwater pumping could have impacts on stream flows in San Luis Obispo Creek, adequate historical data is not available to quantify the impacts. Based on the difficulty and expense associated with analyzing the potential impacts, staff proposes that a revised project strategy be developed to allow the additional use of the groundwater resources at this time, while not limiting the potential to increase groundwater production in the future. The proposed strategy will develop the necessary facilities to allow the City to produce 500 acre feet of groundwater production as identified in the adopted Water Management Element. In addition, the project would include an exchange of recycled water from the City's water Reclamation Facility with agricultural groundwater users. Agricultural exchange opportunities could provide an additional 400— 800 acre feet of groundwater for City potable uses. Background Table 1: Groundwater Production Year Acre Feet The City's Urban Water Management Plan and the Water 1989. 474 Management Element of the General Plan identifies an 1990 1,955 ongoing yield of 500 acre feet of groundwater towards the 1991 1,954 adopted safe annual yield to meet community water 1992 1,543 demands. The City has produced above the 500 acre foot 1993 540 level but adopted the 500 acre foot amount based on 1994 267 minimizing potential impacts associated with pumping 1 1995 250 higher amounts. Due to groundwater contamination of 1996 365 several wells,this level of production has not been available 1997 300 since 1993. Table 1 shows the historic production of 1998 289 groundwater since the . City reactivated the use of 1999 159 groundwater in response to the drought in 1989. As the 2000 265 figures indicate, the City had used almost 2,000 acre feet 1 2001 247 3 - � Council Agenda Report—Groundwater Development Page 2 per year for several years during the drought,but production has averaged below.300 acre feet since the loss of key wells in 1992/93. The groundwater in the vicinity of the Dalido property is contaminated with PCE which was removed at treatment facilities by the City using activated carbon. In 1992/93,nitrate contamination forced the shutdown of the Auto Parkway and Denny's wells. The carbon treatment facility at the Auto Parkway well was decommissioned and removed from the site and the well was abandoned. The carbon treatment facilities were declared surplus and sold shortly after the decommissioning. Utilization of the groundwater resources will require treatment for removal of the nitrates and PCE to allow for potable use of this water supply. Proposed Strategy On February 19, 2002, the City Council approved a contract with Cleath and Associates for assistance with investigation and siting of new wells to provide additional groundwater production. The goal would be to centrally locate new wells to allow increased production and treatment at one location. The City is in the process of drilling exploratory wells in the area south of the Water Reclamation Facility as a potential location for the centralized treatment facilities. If groundwater production in this area is sufficient, abandoned wastewater treatment facilities near Los Osos Valley Road may be able to serve as the site for the new groundwater treatment facilities. Based on past studies and the difficulty in determining the specific direct impacts to flows in the creek resulting from significant increases in groundwater production, staff would recommend a revised strategy for moving forward with the groundwater program. The City's policies identify 500 acre feet of groundwater as a production goal. The achievement of this goal is limited at this time due to the groundwater contamination. In addition to the 500 acre feet currently identified for use by the City, there is the potential to exchange recycled water for agricultural uses in the area and thereby reduce or eliminate the agricultural pumping of the groundwater basin. The City could then increase our use of the groundwater basin by the amount that agriculture has typically used and avoid any additional impacts to creek flows. It is currently estimated that agricultural groundwater uses 400-800 acre feet per year from the groundwater basin. The project would be designed assuming 500 acre feet of agricultural exchange which would be added to the 500 acre feet currently identified in the Water Management Element for a total facility production capacity of 1,000 acre feet per year. This - proposed project strategy would allow the City to move forward with utilization of the groundwater resources at this time with potentially insignificant environmental impacts. The City Council has been supportive of increasing the use of the available local water resources which are under the City's control. Assuming that production from the exploratory wells in the fields south of the Water Reclamation Facility is sufficient to meet the 1,000 acre foot goal, staff would recommend That a request for proposals for consulting services be prepared for Council approval. The scope of work would include siting and preliminary design to facilitate the environmental review required under CEQA. The CEQA analysis would include an evaluation of 3-a Council Agenda Report—Groundwater Development Page 3 the project impacts based on the groundwater pumping and agricultural exchange as discussed above. The facilities siting and design will consider the potential for future increases in groundwater production during drought emergencies or with an expanded groundwater program, but the initial capacity will only be designed for the 1,000 acre feet of annual production as defined in the current project. The CEQA analysis will be limited to the defined project goal of 1,000 acre feet and future expansions will undergo additional analysis at that time. FISCAL IWACT The 2001-03 Financial Plan (Appendix B Capital Improvement Plan, Pages 108-109) identifies $50,000 for site evaluation and preliminary design and $150,000 for design. The exploratory well drilling discussed above will utilize $27,500 of these available funds. Therefore, there is $172,500 available to support the siting and design for the grbundwater development project. Staff will return to Council for approval of the request for proposals which will identify the estimated funding needed to support this effort. 3 -3