Wellhead Protection

The Town of Edinburgh, Indiana relies on groundwater to supply drinking water to approximately 5,000 customers in and around the Edinburgh area. For this reason, Edinburgh has contracted with Strand Associates Inc.Engineers to prepare this well field delineation report as part of its effort to comply with wellhead protection rules adopted by the Indiana Water Pollution Control Board in March of 1997 coded in 327 IAC 8-4.1. Edinburgh is considered a medium sized community under the regulation and must submit a draft Phase I Wellhead Protection Program no later than March, 2001.

The Town of Edinburgh is located in the southeast corner of Johnson County with services extended into adjacent areas of Bartholomew and Shelby County. The total population of Edinburgh is estimated at 4,500. The Town utilizes water from one well field.

The Town began using groundwater from the current well field in 1929 with a single groundwater well ( Well # 1 ). Groundwater use expanded with an additional well in 1938, 1956 and two wells in 1967. Some old wells were abandoned and replaced with similar wells in the history of the utility. The four production wells currently are identified as Well # 1, Well # 2, Well # 3, Well # 4. The wells vary in depth from 81 to 109 feet.

The wells are used in various combinations to supply water to the treatment plant that is capable of treating up to 1.4 million gallons per day. At the present time there are no plans to expand either the well field or capacity of the treatment plant. The treatment plant performs iron filtration and chlorination, fluoride treatment and phosphate treatment before distribution to the system. The water plant supplied in excess of 253 million gallons of water in 1997 or about 700,000 gallons per day.

The hydrogeology of the Edinburgh well field can be described as a vast aquifer of highly transmissive sand and gravel deposits that are unconfined in the Edinburgh area and southward beyond Columbus. These sand and gravel become overlain by clay till north and northeast of Edinburgh and eventually thin and pinch out to the far north toward New Castle, well beyond the study area. The highly transmissive aquifer materials abruptly end west of Edinburgh at the western border of the Wisconsinan outwash valley as discussed earlier.

The major surface water contribution to local hydrogeologic system influencing the Edinburgh well fields is the Big Blue River. The river is expected to have a good connection to the aquifer in the Edinburgh area due to extensive sand and gravel outwash deposits in the near surface or surface environment. This is visibly verified by the many gravel pits in the area around Edinburgh. A direct connection to the aquifer is not expected north and northwest of Edinburgh where surficial clay till materials may underlie the river bed.

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