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Home My WebLink About04/18/1989, 3-B - CONSIDERATION OF TREATMENT OPTIONS TO REMOVE TETRACHLOROETHYLENE FROM THE DALIDIO GROUNDWATER BASIN �u� nNI�P SII City of San tins OBISPO Apra 1j,89 COUNCIL AGENDA REPORT ITEM BER• FROM: William T. Hetland Prepared By: Allen Short Utilities Director Water Division Manager SUBJECT: Consideration of treatment options to remove Tetrachloroethylene from the Dalidio groundwater basin. RECOMMENDATION: Adopt resolution authorizing CAO to enter into a contract for treatment to remove Tetrachloroethylene from the Dalidio ground water basin. BACKGROUND At the March 3, 1989 City Council meeting, Andrew Merriam (representing the Dalidio family) presented the City Council with an offer to use groundwater located beneath the Dalidio property. The offer was made to assist the City through its present water shortage. The first step taken after the offer, was to arrange for and collect water samples at all well locations on the Dalidio property. The collection of samples was required to determine existing water quality characteristics and establish that if the water met current water quality standards established by both the State and Federal governments. The laboratory selected to perform the sample collection and analysis was Central Coast Laboratory located in San Luis Obispo. The laboratory analysis has been completed and the results have arrived. The analysis identified two Volatile Organic Compounds (VOCs) ; Tetrachloroethylene (PCE) and Trichloroethylene (TCE) . The Tetrachloroethylene was the primary contaminant, with only a trace of Trichloroethylene. At the April 5, 1989 City Council meeting staff presented Council with two proven treatment options which would remove tetrachloroethylene from the Dalidio groundwater. The City Council directed staff to investigate the costs, and viability of each option. TREATMENT TECHNOLOGIES: Proven technology exists to remove these contaminants from the water in order to meet health standards and make it safe for human consumption. The two most commonly used technologies are air stripping using packed-tower aeration and carbon absorption. RECEIVED ITYZLERN h1:Drd f', OV t- city of san Luis oBispo MoZe COUNCIL AGENDA REPORT Tetrachloroethylene Page 2 1. Packed-tower Aeration - Packed-tower aeration uses a vessel filled with special packing material that provides good contact between water and air. Water is introduced at the top of the tower and trickles down through the packing. Air is forced or drawn upward through the packing by a blower. The VOCs are transferred from the water to the air during their contact in the packing, then exhausted with the air to the atmosphere at the top of the tower. The initial cost of this technology can be as much as 50 percent less than the cost of granulated activated carbon. However, there are a number of hidden costs which are not readily available or quantifiable. Additionally, the primary disadvantages to this technology are: * Flow variations; Flow much different from design will cause performance to deteriorate. * Fouling; Packing fouling of any type will disrupt mass transfer causing performance problems. * Contaminant variations; Increase in contaminants, new contaminants or mix in contaminants may cause effluent to exceed design levels. * Oxygenation; Air strippers will increase oxygen content of the water, which may in some cases cause corrosion problems in distribution system. * Monitoring costs; Monitoring needs to be much more frequent than for granulated activated carbon, and should include monitoring of adsorber off-gas. * Added electrical costs; Blower, pumps_, etc. begin to be expensed immediately. * Non-volatiles; Air strippers well not remove non-volatile contaminants, some of which may be under SOC rules, such as pesticides, etc. , some of which may cause THM formation, or some of which may cause performance. * Cleaning costs; If the packing becomes fouled, cleaning is necessary involving cost of equipment, manpower, cleaning chemicals and disposal of chemicals. * Size; Air strippers are usually taller than GAC units and therefore could have a greater impact on siting requirements. 2. Granulated Activated Carbon (GAC) absorption - GAC absorption takes place in a closed vessel where the water passes through a bed of activated carbon. The VOCs are absorbed onto the carbon's pore structure. Contact time is very important, usually requiring 10-15 minutes. I The initial cost of this technology can be as much as 50 percent higher than the cost of air stripping. However, the primary disadvantages to this technology are: c6 -0/✓ a2. �►�►�r� ally � N city of San LUIS OBispo COUNCIL AGENDA REPOFW Tetrachloroethylene Page 3 * Carbon replacement; carbon must, depending on the contaminate concentrations, be periodically replaced. * Capital costs; Initial capital costs are higher. COST OF TREATMENT OPTIONS Staff has met with with a number of representatives, in the field of carbon filtration and air stripping to review options available to the City for treating the Dalidio groundwater. The following is a summary of the viable carbon treatment option. The table below summarizes these options. Summary of Treatment Options Company GPM Cost Delivery Date Filtronics (Carbon) 700 $ 378,000 6/26/89 - 7/10/89 Calgon (Carbon Bed) 1300 384,000 6/12/89 - 6/26/89 Breuner Corp. (Air Stripped) 1200 270,000 7/10/89 - 8/21/89 Geoservices (Air Stripped) 700 255,000 Remedial Systems, Inc. (Air Stripped) 1725 110,000 6/12/89 - 7/10/89 Calgon (Air Stripped) 1400 200,000 8/21/89 - 9/4/89 Calgon (Air Stripped) 1400 175,000 8/21/89 - 9/4/89 Tri-Mer Corporation (Air Stripped) 900 355,796 7/24/89 - 8/21/89 Staff is recommending the carbon absorption process be used because it provides a greater level of treatment and flexibility in types of contaminants it can remove. It also tends to be more portable and could therefore be used at other sites. In an effort to keep the costs down, staff is also recommending that only a single carbon unit be purchased immediately. This would provide a capacity of 700 gpm (1100 AF/Y) for a cost of about $195,000. Staff would continue to investigate treatment alternatives while additional well drilling takes place. Whether additional treatment is provided depends on the results of the water quality and quantity from the new wells. ��IpN city of San tuts OBISpo COUNCIL AGENDA REPORT Tetrachloroethylene Page 4 STATE HEALTH SERVICES The State of California, Department of Health Services (State) recognizes both air stripping and use of granulated activated carbon as viable technologies to remove PCE and TCE. However, the State does have three requirements prior to the installation of a treatment unit. (1) The recommended system must be reviewed and approved by a registered engineer in the field of water treatment prior to installation. (2) If the recommended option is GAC treatment, they prefer the units be operated in series. (3) The Department of Health Services will require that the City establish a sampling schedule. This schedule would require approval prior to start up. In addition, monthly reports indicating level of system operation will be required. CONSEQUENCES OF NOT TAKING ACTION: If treatment and removal of PCE is not provided; * The City would not be in compliance with the State and Federal Water Quality Regulations. * The State would not grant the City an operations permit and we would not be able to use the water from the Dalidio wells for domestic consumption. FINANCIAL IMPACT: The recommended treatment option is approximately $195,000. The cost per acre foot is $14.50. This is capital costs amortized over 10 years at 8 percent, and does not take into account power, labor, or additional monitoring requirements. This cost does not include any fees paid to the Dalidios. There are adequate funds in the water fund to cover. this project. This expenditure may require an evaluation of priorities for new CIP projects and projects which have been approved but not completed. Those projects with a low priority will be eliminated and the money will then be used to fund this project. RECOMMENDATION• Adopt resolution authorizing CAO to enter into a contract for treatment to remove Tetrachloroethylene from the Dalidio ground water basin. I �IIItuujpMIjj city of san tuts oBispo WMA COUNCIL AGENDA REPORT Tetrachloroethylene Page 5 APPROVED: City dministrative Officer City At ey FYIRce Director Utilities Director I X45 RESOLUTION NO. (1989 SERIES) A RESOLUTION OF THE COUNCIL OF THE CITY OF SAN LUIS OBISPO AUTHORIZING THE CITY ADMINISTRATIVE OFFICER TO ENTER INTO A CONTRACT FOR TREATMENT TO REMOVE TETRACHLOROETHYLENE FROM THE DALIDIO GROUNDWATER BASIN WHEREAS, the City of San Luis Obispo is in the process of negotiating an agreement to use the groundwater under Dalidio land for an emergency supply; and WHEREAS, the laboratory analysis have found levels of tetrachloroethylene above the State maximum contaminate levels; and WHEREAS, tetrachloroethylene is classified as a know or Probable human carcinogen by the Environmental Protection Agency (EPA) ; and WHEREAS, the technology exist to effectively remove tetrachloroethylene from contaminated water; NOW, THEREFORE, BE IT RESOLVED that the Council authorizes the City Administrative officer to enter into a contract for the treatment and removal of Tetrachloroethylene from the Dalido groundwater basin, in an amount not to exceed $250,000. On motion of seconded by , and on the following roll call vote: AYES: NOES: ABSENT: the following resolution was passed this day of 1989. MAYOR RON DUNIN ATTEST: CITY CLERK PAMELA VOGES -.46 - .dEETING AGENDA DATE ITEM # �; ��Ilnallllllllllllhlllllll��l�lllll►1111, � iAskIII city Of SAn luls OBISPO 990 Palm Street/Post Office.Box 8100 • San Luis Obispo, CA 93403-8100 Denotes action by lead Person Respond by: 07founca April 18, 1989 &CA0 ray Afty. 1'GTe*_0 �,B•HttAAroo MB MORAND OM T. To: City Council From: John Dunn, City Administrative Officer 2 Subject: Phone Call From Mrs. Monica Bryant Miguel Concerning "Closing Off" of Santa Margarita Lake Mrs. Monica Bryant lives in San Miguel (467-3627) . She said she is very concerned, about the City's plan to "close off" Santa Margarita Lake meaning that the water would no longer be availble to the North County area. .Though she lives in San Miguel she also has a house in Atascadero and believes that Templeton and other areas will be similarly concerned. She suggested that we had "better be prepared" for the reaction from the North County. I informed her that what she had heard on T.V. was a proposal of a Councilmember and that the motion had to be acted upon by the City Council. She asked, and I agreed, that her concern be passed onto the City Council members. JD:sl C 1