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II. SCOPE OF SERVICES: Phase I: Evaluation and Ranking I. Initial Ranking (Aquatic Health) CONSULTANT will review the existing analyses the COUNTY has performed, analyze existing historical utility records, existing as-built's, utilize the Indian River County Utilities Geographic Information Systems' (GIS) data, and utilize other maps, records, reports and documents pertinent to this study. The CONSULTANT will use this data and develop a rational numerical indexing system of physical and environmental factors that influence the potential discharge of nutrients from existing OSTDS and its migration through sub -surface and surface waters to the Indian River Lagoon and its tributaries. The CONSULTANT will derive a mathematical formula and develop spread sheets which enable a numerical analysis of these factors that will result in the ranking and prioritization of the conversion of approximately 345+- geographic areas in IRC that currently utilizing onsite sewage treatment and disposal system to centralized collection and treatment sewer utility system. It is anticipated that the numerical prioritization will be based upon at least the following physical and environmental factors for determining the initial ranking and prioritization: • Population Density for Loading Concentrations • Proximity to Surface Waters • Location of the Community in Relation to the 100 -year Flood Plain — FEMA Flood Plain • Depth of the Ground Water Table • Soil Conditions of the Drain Field — Soil Type • Age of the Surface Water Management System • Age of the Existing OSTDS The soil type and water table will be determined by referencing published geotechnical data obtained from the USDA -Natural Resource Conservation Service Soil Survey and other available information, and existing survey or GIS data that may be provided by IRC. No new survey or Geotechnical field work will be obtained. COUNTY staff has already prepared an initial/ preliminary evaluation and researched some of the parameters mentioned -above. This information will be made available to the CONSULTANT in order to keep man-hour cost down. However, it will be the responsibility of the CONSULTANT to verify the accuracy of the provided data/information. As part of the evaluation the study area will be restricted to the Indian River County Utilities Service area within the Urban Service Area (USA). Furthermore, the evaluation will be limited to areas with clusters of existing OSTDS and not large individual parcels with existing OSTDS. The top 30 areas identified in this initial ranking (areas of highest priority to convert) will be included in further evaluations as outlined below. 2. Sanitary Sewer System Evaluation and Cost Estimate CONSULTANT will review various types of sanitary sewer collection and transmission systems, including gravity sanitary main sewer collection system with conventional lift station, vacuum sewer collection system with vacuum pits and pump station, and low pressure force main with individual grinder stations for each of the 30 70 2