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9 <br /> APPROACH: <br /> The project will have three major work tasks. The first two are designed to characterize <br /> ground-water availability and ground-water quality in the county. Study results will be <br /> summarized in a published report and electronic documents. The third task involves <br /> participation in meetings at the conclusion of the study to present study results and to identify <br /> potential uses of the results for planning and management purposes. <br /> Task I—Ground-Water Availability <br /> This component will involve compilation and analysis of available information on <br /> hydrogeology,soils,topography,well construction,static water levels,well yields,water use,and <br /> population. Information on wells will be compiled from Orange County,State and Federal <br /> agencies.well drilling companies,and well owners to obtain a database of a size(number of <br /> records)suitable for statistical analysis and mapping of the distribution of well yields,depth to <br /> the water table,thickness of regolith,and other ground-water related characteristics across the <br /> County. The characteristics of each major aquifedhydrogeologic unit will be described in <br /> relation to properties such as well yield,specific yield,and lithologic composition. <br /> 1. Evaluate the distribution of well yields: <br /> A major goal of the study will be to develop a data base of well records that have been field <br /> checked and that is sufficiently large to perform statistical analyses with high significance. The <br /> statistical analyses will be made to relate well data to hydrogeologic information and water-use <br /> information for the purpose of projecting well yields,estimated future groundwater use,and <br /> overall carrying capacities of various subsections of the study area. It is acknowledged that there <br /> exists an inherent problem of biases that arise from the selection of various types of wells,well <br /> data,well sites,and well construction techniques. The investigation,to the extent practicable, <br /> will use techniques that compensate for these biases to produce an accurate picture of the <br /> quantity of ground water present and available for consumption. <br /> The most recent geologic and hydrogeologic unit maps available will be digitized and will <br /> form the basis for describing bedrock geology and hydrogoology in the County. A well inventory <br /> of about 400 water supply or observation wells will be conducted. These wells will be selected <br /> to provide statistically representative samples of well characteristics within the major <br /> hydrogeologic units in the County. Well characteristics of particular interest include yield,total <br /> depth,casing depth,diameter,and static water level. The major hydrogeologic units consist of <br /> metaigneous and metavolcenic rocks of various cormpositions and phyllite. Lesser areas are <br /> underlain by argillite and sedimentary rocks of Triassic age. The locations of all inventoried <br /> wells will be verified by site visits;latitudes and longitudes will be determined from topographic <br /> maps or by a Global Positioning System(GPS)instrument. Well records will be compiled into <br /> digital files that can be transferred to the County's computer system;this information will also be <br /> entered into the U.S.Geological Survey's Ground water site Inventory(GWSl)database. <br /> s <br />