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4D <br />4W <br />40 <br />40 <br />ATTACHMENT B <br />SCOPE OF WORK <br />Task 1304 - ENGINEERING SERVICES FOR WELL REHABILITATION <br />SOUTH COUNTY WATER TREATMENT PLANT <br />Background <br />The South County Water Treatment Plant is approximately 18 years old. Raw water is <br />supplied by six wells constructed into the Floridan Aquifer. The depth of the wells <br />reportedly ranges between 600 and 700 feet below ground surface. Wells 1 through 3 were <br />the initial wells constructed with the original plant. Wells 4 through 6 were installed at <br />a later expansion to the facility. <br />Potential problems with the wells were identified by County operation staff through the <br />degradation in the performance of the cartridge filters upstream of the reverse osmosis <br />treatment units. County staff were required to change the filters approximately once every <br />six months under normal operating conditions. Performance life of the filters has been <br />much less in the last six months to a year due to clogging by a form of bacteria. <br />Phase I engineering services (previous Work Authorization No. 11) included investigating <br />the physical and mechanical condition of the existing six wells which provide raw water <br />to the plant. CDM worked with County staff, as necessary, and performed the following <br />tasks/items: <br />r Field visit well sites to determine physical conditions of equipment, piping and the wells. <br />■ Review available water quality and operation data for the wells and treatment facility, <br />d Recommend immediate improvements and/or additional water quality sampling. <br />v Fonnuiate a work plan for rehabilitation of wells. <br />The work plan was submitted and reviewed by County operation staff and is included as Attachment <br />C. This work plan is the basis of the scope for engineering services to be cowered in this work <br />authorization (Phase II). <br />Services <br />Phase Il services incorporate the necessary rehabilitation efforts for the existing six wells <br />at the facility. This effort entails subcontracting with a licensed well contractor to perforin <br />the field work along with coordination efforts by CDM staff as described in Attachment C. <br />Additional services are included for investigation of the well electrical system in regards <br />to emergency operation procedures in the event of power failure. Three wells are currently <br />connected to the facility's onsite generator. This investigation will evaluate costs <br />associated with connection to the existing system, portable generator purchase, and <br />permanent well generators for the remaining three wells. Design services of the most cost <br />effective/option is also included. <br />,bsas± <br />