# Presentation: 466681

## Identifying Sensitive Aquifers in Ohio

**Chris Kenah,  Michael. W. Slattery,  Linda. D. Slattery, and Michael Eggert **
**Ohio EPA, Division of Drinking and Ground Waters**

**DMT’06**

## Outline

**Logic for identifying sensitive aquifers**
**Suspected sensitive aquifers**
**Water Quality/SWAP data - Impacted PWSs**
**Analysis of ODNR glacial aquifer attributes and location of impacted PWSs**
- Differences between geologic setting and lithologic attributes
**Ohio Sensitive Aquifers**

## Slide 3

## Data Sources

**Geologic Information**
- Recharge Pathways
- ODNR Aquifer Maps
**PWS Compliance and Ambient Data**
- Nitrate, VOC, SOC
**Special Study Knowledge**

## Logic for Sensitive Aquifer ID

**Short or Rapid Recharge Pathways **
**Areas of Ground Water - Surface Water Interaction**
**Recharge through Glacial Drift**
- Identify glacial settings with rapid recharge

## Slide 6

## Sensitive Glacial Settings

**Buried Valleys - sand & gravel aquifers**
- Fine to coarse grained material
- Buried valley, alluvial, out wash/kame, and beach ridge geologic settings
**Thin Glacial Drift - over bedrock aquifers**
- Fined grained - tills and lacustrine deposits
- Lacustrine, ground and end moraine settings

## Ohio SWAP Program

**SWAP Susceptibility Analysis**
- Includes evaluation of compliance data;
**516 PWSs Highly Susceptible **
- Based on water quality compliance data
- Nitrate > 2.0 mg/L
- VOC or SVOC detections

## Slide 9

## WQ Impacts in Sensitive Aquifers?

**Attach glacial aquifer attributes to PWS locations**
**Evaluate PWS WQ impact association with:**
**Glacial geologic settings**
**Glacial lithologies**
**Compare percentage of PWSs impacted**

## Data Limitations 

**ODNR aquifer maps thickness are ranges not well depths**
**If glacial drift < 25’, bedrock production well likely**
**If glacial drift > 25’, production may be in drift**
**In thicker glacial sand and gravels, well depth may not approach glacial drift thickness**
**In thicker till lithologies, production may come from sand lenses or bedrock**
**Utilizing statewide generalizations**

## Rapid Recharge to Fractured Bedrock 

**Rapid Recharge to Fractured Bedrock**

## PWS Water Quality Impacts - Geologic Settings

**PWS Water Quality Impacts - Geologic Settings**

## PWS Water Quality Impacts – Lithologic Association

**PWS Water Quality Impacts – Lithologic Association**

## Slide 15

## Sensitive Aquifers

**PWSs with WQ impacts associated with:**
- Coarse S&G aquifers
- Thin Tills (0-25 ‘)
**Aquifers composed of fines provide more protection than S&G aquifers and thin tills over bedrock aquifers;**
**Thick tills are associated with low % of PWSs with WQ impacts (3-4 %) **

## Slide 17

## Future Activities - Sensitive Aquifers

**Attach glacial drift thickness, DRASTIC ranking, and soil properties to PWS locations for analysis of WQ impacts **
**Incorporate well casing length and depth as analysis factors**
**Evaluate dissolved vs particulate sensitivity**
**Identify areas where horizontal flow pro-vides rapid recharge**
**Short term sampling in sensitive aquifers**

## Rapid Horizontal Recharge Linked with Flooding 

**Rapid Horizontal Recharge Linked with Flooding**

## Acknowledgments

**Data**:
-  Ohio EPA Staff
-  PWS Operators
-  ODNR Aquifer Map

**GIS Support**:
-  Ohio EPA, DDAGW GIS Unit