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2012-68 El TETRA TECH October 1, 2012 Ms. Tamara Richardson, P.E. Director of Engineering City of Clermont 685 W. Montrose Street Clermont, Florida 34711 Subject: City of Clermont Professional Services Proposed for the DBP Study Tt#: 200-08310-11001 Dear Ms. Richardson: Tetra Tech is pleased to furnish this proposal for professional services related to the disinfection byproduct study for the Disston and Fourth Street Wells. A detailed scope of services is attached. Tetra Tech looks forward to serving the City of Clermont on this project. If you should have any questions, please do not hesitate to contact me at 407-839-3955. Very truly yours, Approved: Tetra Tech City of Clermont Jon D. Fox, P.E. By: Vice President Date: I©-ca-Ct2.. Attachments BAF/sma/ier/08310-11001/proj mgmt/corresp/Richardson_SCADA App C: Brian Foulkes,P.E.,Tetra Tech Sally Alfieri,Tetra Tech Tetra Tech, Inc. 201 E.Pine Street,Suite 1000,Orlando,FL 32801 Tel 407.839.3955 Fax 407.839.3790 www.tetratech.com ATTACHMENT "A" SCOPE OF SERVICES Westside Water Treatment Plant Disinfection Byproduct Study A. BACKGROUND The Westside Water Treatment Plant(WTP)project is in the final design stage and water quality from the on-site Disston Well was recently obtained from packer tests during construction of the well. Onginal assumptions for the design of the WTP assumed total organic carbon (TOC) less than 2.0 mg/1 Water quality results indicate TOC levels greater than the assumption, which can increase the potential formation of disinfection byproducts. This proposal presents the services required to complete the field work to collect the samples as well as the engineering services and laboratory services to analyze the data and produce a treatment feasibility memorandum based on the presence of the elevated TOC in both the Disston Well and Fourth Street Well. The following tasks will be undertaken in order to complete this study • Raw water collection and testing • Bench scale disinfection by product(DBP)formation potential analysis • Review of the data and opinion of additional treatment.required, if any B. SCOPE OF SERVICES Task 1—Raw Water Collection and Testing A. All tests will be conducted on raw water samples collected by Tetra Tech staff dunng the aquifer performance test (APT). Labor costs associated with being on-site during the APT test were included in the previous Disston Well scope of services. Additional labor hours associated with sampling are for coordination with the lab to order sampling kits, picking up and dropping off sampling kits and coordinating sampling with field crews. B. Raw water samples will be collected for three(3)types of testing. 1. Three(3)water samples will be collected dunng the APT from the Disston Well and two (2) water samples from the Fourth Street well are to be analyzed by an outside commercial laboratory for select constituents such as total sulfide,bromide,total organic carbon (TOC), dissolved organic carbon (DOC), UV absorbance, calcium, magnesium, and alkalinity A field test will be used to determine the conductivity and pH of the raw water from each source. For quality control purposes, each sample will be split so duplicate testing is performed. 2 A single water sample will be collected at each source water to be analyzed for a chlorine demand study and disinfection byproduct formation study. Disinfection byproducts include Total Tnhalomethanes(TTHM)and Haloacetic Acids(HAAs). ° TETRA TECH BAF/slh/pm/contract/co/DBP Scope 9.24.12 Q Tt#200-08310-11001 -1- 092412 Task 2—Disinfection Byproduct(TTHM and HHAs) To determine the disinfection byproduct formation (DBPF) potential in the raw groundwater at both the Disston and Fourth Street Wells, a Chlonne Demand/Decay (CD/D) study and a Simulated Distribution System DBPF(SDS-DBPF)study will be performed The primary goal of the CD/D testing is to evaluate the free chlorine demand and chlorine residual decay of the raw groundwater to determine the necessary chlonne dosage to maintain a residual in the distribution system over a period of 7 days. This study attempts to simulate chlorine residual decay of chlonnated water inside a distribution system by dosing chlorine solution into amber glass bottles containing water samples. Various chlorine dosages will be performed for each source water in order to determine the target chlonne dosage for the SDS testing The Chlonne Demand/Decay study will be performed in accordance with Standard Method Procedure 2350 B. The pnmary goal of the SDS-DBPF study is to evaluate the rate of formation of THMs and HAA5s in the groundwater when exposed to a free chlonne residual Aliquots of raw groundwater will be added to amber glass bottles and will be dosed with the target chlorine residual from the Chlorine Demand/Decay study. Bottles will be dechlonnated and preserved at pre-selected chlonne contact times,and then sent to a certified commercial laboratory to determine the THM and 'HAM concentrations. Two curves consisting of at least 7 samples for each source water will be analyzed at different chlorine contact times in order to determine the rate of THM and HAAS formation and to compare the results to the FDEP maximum contaminant limits(MCL)for THMs and HAA5s. The SDS-DBPF study will be performed in accordance with Standard Method Procedure 5710-C Task 3—Final Memorandum A final report will be delivered containing a summary of water quality results and THM and HAA formation potential, as well as the conclusions and recommendations for the proposed treatment feasibility. Four draft (4) copies of the Memorandum will be forwarded to the City for review Following a review meeting to discuss any comments, four(4) copies of the final Memorandum will be delivered to the City. C. COMPENSATION SUMMARY The proposed Lump Sum compensation for the Scope of Services descnbed above is $17,135.00 as described in Section B. BAF/s1h/pm/contract/co/DBP Scope 9.24.12 a TETRA TECH Tt#200-08310-11001 -2- 092412