Mill Creek Area Public Water Extension Project
A GIS project database to assist in evaluating the feasibility of bringing
public water to a rural area of northern Orange County, NC
Submitted by Joe Forrest
Geography 193
February 21, 2005
Background
The area around Mill Creek Road in northern Orange County has been traditionally a quiet, rural area of farmland, off the beaten path. In the last five years, though, the area has experienced a high rate of growth. Many small subdivisions (10-50 homes) have been built or are under development along the road or along adjacent roads, and the prospects for future growth are high. Land is relative inexpensive, and the area is an easy commute to Mebane, Graham, Burlington and Hillsborough where many residents work. The area affords low property values (and thus low taxes), affordable housing and a quiet rural atmosphere. Since there is no public water supply in the area, all homes have wells and septic tanks.
Unfortunately many properties in the area have experienced severe problems with their water wells. Complaints include discolored and malodorous water, and high levels of radon are suspected. Wells often have very low pressures. The proximity of septic systems to the wells poses the added possibility of future contamination, especially where wells and septic systems are in close proximity, as they are in the new subdivisions. As in all areas of the Piedmont, wells in the Mill Creek area are subject to freezing during winter months, drying-up during summer droughts and equipment failures at all times. A group of concerned citizens has been formed to explore the possibility of getting public water in the area. The Orange-Alamance Water System has expressed interest in extending their system into the Mill Creek area, if the residents can find the necessary funding, which will not be inconsiderable.
At this stage the Mill Creek concerned citizens group is trying to interest other residents in the project and to put together a more formal organization that can represent the area before regulatory and funding agencies in Hillsborough, Raleigh and Washington. The process of assembling interested property owners is a tedious one. Property owners must be identified and contacted to ascertain their level of interest. An undetermined number of residents must commit to subscribe to public water to justify the project. And the process of securing funding will be daunting in these days of austere government budgets.
The Mill Creek Road concerned citizens have a number of tasks ahead of them. First they must determine the number of property owners who would commit to subscribe to a public water system if constructed. Second they must determine a proposed extension area that is supported economically by the level of interested property owners. Third they must document well and water problems and their geographic distribution in the area. To initiate these tasks the concerned citizens are distributing flyers in local churches to invite interested property owners to attend regularly scheduled monthly meetings. This will be followed up in the near future with a survey form that will be distributed by mail to all residents in the potential service area. If enough interest is expressed the effort can proceed.
Proposed GIS Project
I propose to create a GIS database with some customized functionality to assist in the evaluation of the proposed Mill Creek Public Water Extension. The purpose of the system will be as follows:
1. To display a base map of the Mill Creek area that shows location of the area, its roads, land parcels, topography, location of homes and businesses that are potential users of public water, and relationship to the present OAWS system supply network.
2. To determine and document environmental problems that affect water quality and well performance in the area (rock types, radon levels, mineral content, depth of bedrock weathering, water table flow patterns).
3. To assist in identifying property owners, and their addresses, laying out various potential routes and estimating distances along these routes to maximize the number of potential customers and justify the economics of the project.
4. To maintain a growing database of information on interested property owners, including names, addresses, level of interest, problems they have encountered in their wells and the locations of these wells.
The main data types in the project will include the following:
1. Georeferenced USGS topographic quad sheets at a scale of 1:24,000 (Efland, Mebane, Burlington North and Cedar Grove quadrangles).
2. The Land Parcel shapefile maintained by the Orange County Land Records Department in Hillsborough. This polygon shapefile contains the shapes locations of all land parcels in the county and attributes that detail land ownership, owner’s addresses, and presence of buildings on properties.
3. A centroid shapefile developed from the parcel shapefile. This file will show the centroid location of each parcel and will be the mapping location for specific data related to that parcel. It will also be assumed initially that any residence on the parcel is located at this centroid (This is certainly almost never the case, but since we lack any accurate data on building locations this centroid must suffice).
4. A georeferenced map of the OAWS will be used to develop a shapefile of that system’s present supply network, to demonstrate its relationship to the study area.
5. A shapefile will be developed of all wells in the area from records obtained from county and state regulatory agencies. These will be used to document the depth to base of the aquifer in the area. This information, along with the topographic sheets, is important for determination of groundwater flow patterns in the area. These records may also contain additional useful information, such as reported well problems, testing done by the North Carolina Department of Environment and Natural Resources (NCDENR) or the Orange County Planning Department.
6. A georeferenced geologic map will be used to develop a shapefile of subsurface rock units in the area. Since the water-bearing aquifer in the areas consists essentially of weathered bedrock, this file provides an important documentation of the nature of the aquifer and its mineralogical content, which may account for many of the problems encountered in the wells and quality of their water.
The following customized functionality will be developed:
1. Forms to input data gathered through the survey process. As surveys are returned, these forms will allow the user to quickly retrieve data on the property owners and to enter their survey responses (level of interest in having public water, willingness to serve on committees, problems they have had with their wells, location of their properties, etc.). This data will be added to attribute tables of the land parcel shapefile and the land parcel centroid shapefile so it can be graphically displayed and mapped.
2. A simple function to allow the user to (1) input a line segment from a shapefile, (2) specify a buffer around that line, and (3) return parcels that intersect the buffer and their attributes. This function will have several purposes. First it will be used to interactively determine and test various routes for a potential water supply extension. Users will draw line segments, representing potential supply line routes, along roads and will specify a buffer distance around the segment. This buffer will select all land parcels that intersect it and return these parcels and their attributes (including owners, addresses, etc.). Secondly, the returned attribute data will be used to calculate statistics. Numbers of properties along each segment will be summarized to ascertain the route with maximum subscriber potential. The density of residences will be estimated using the numbers of buildings on the parcels. The distance of buildings from the road will be estimated using the actual buildings or the centroid of the property (important in estimating the potential cost to property owners of hooking into the main water supply line). The various defined routes will be given ID’s and will be joined with the land parcel information they select in a new layer for future retrieval and display.
The completed database will be an invaluable tool in determining the feasibility of extending public water to the Mill Creek area. It will assist in locating property owners in the area, in determining the optimum route of supply lines, and will permit the various factors involved in the evaluation to be graphically displayed and mapped.
The proposed project can be completed as outlined within one month.