Paul Kirby, P.G. Daniel B. Stephens & Associates, Inc. with Fayette County GCD Pecan Valley GCD August 29, 2018
Typical GCD Mission To provide for the conservation, preservation, protection, recharging, and prevention of waste of groundwater and groundwater reservoirs...protecting, preserving and conserving aquifers......manage and protect the groundwater resources...
Protecting Groundwater Most districts have active groundwater level monitoring programs Fewer are developing datasets of baseline water quality Quantity and quality are important Is there enough water? Is it safe to use?
Statewide Historic Water Quality Samples Source: TWDB Database
Single-District Water Quality Studies Fayette County GCD approved a study in 2013; concluded in 2017
Single-District Water Quality Studies Pecan Valley GCD (DeWitt County) approved a study in 2014; concluded in 2018
Purpose of Studies Collect new data to provide additional baseline water quality measurements Establish baseline measurements for activities of concern (fracking, uranium mining, etc.) Evaluate current water quality data and compare to historical studies/data
Project Tasks Define project objectives Review historic data Identify wells to sample and contact well owners Field work Analytical Reporting
Project Objectives What aquifers will be evaluated? Sampling distribution goals Water quality issues/potential issues to address Develop appropriate analytical suites to evaluate general water quality as well as any specific issues identified
FCGCD Hydrogeologic Units System Series Group Quaternary Tertiary Pleistocene and Recent Miocene Formation / Aquifers Approximate Thickness (feet) Hydrogeologic Units Alluvium 0 to 60± Alluvium Oakville Sandstone and 0 to 950 Lagarto Clay Catahoula Tuff 0 to 500 Gulf Coast Oligocene Frio Clay 0 to 520 Jackson Jackson 0 to 1,100 Yegua 0 to 900+ Yegua - Jackson Cook Mountain 0 to 450+ Sparta Sand 0 to 275 Sparta Claiborne Weches 50 to 150 Eocene Queen City Sand 480 to 750 Queen City Wilcox Recklaw 225 to 500+ Carrizo Sand 200 to 300+ Calvert Bluff Simsboro 2,400 to 3,800 Hooper Carrizo-Wilcox
Aquifer Location
Sample Distribution Goal
PVGCD Wells Sampled
Water Quality Issues to Evaluate
Analytical Suites Basic inorganic suite Additional analytic suites for issues of concern Hydraulic Fracking Uranium Mining SVOCs Other?
Historic Data Review Geology and hydrostratigraphy Location and extent of aquifers Historic water quality studies/data Wells previously sampled or measured water levels Other reports/sources?
Well Selection After determining desired distribution of wells, identify candidate wells Can be difficult- depends on data quality available for wells Contact well owners for permission to sample Involves extensive PR This effort very useful in developing relationships with well owners
Time to go sample!!
Purge well for 15 minutes Collect samples directly from faucet Preserve-Label-Seal- Store (on ice) Deliver to lab Sampling Protocol
Analytical Results Review and QA/QC Any detections of concern that warrant confirmation sampling? Begin compiling your data for analysis and reporting Data evaluation Assess by aquifer Comparison to drinking water standards Comparison to historic data/studies Analysis of geographic trends (if any)
Drinking Water Standards Primary Standards MCLs (maximum contaminant levels) Legally enforceable Health-based limits set by the USEPA Secondary Standards EPA or state standards Not enforceable Relate mainly to aesthetics (taste, color, odor, etc.)
Primary Drinking Water Standards Analyte Primary MCL (mg/l) Fluoride 4 Nitrate 10 Arsenic 0.01 Barium 2 Beryllium 0.004 Cadmium 0.005 Chromium 0.1 Mercury 0.002 Lead 0.015 (Action Level) Antimony 0.006 Selenium 0.05 Thallium 0.002
Secondary Drinking Water Standards Analyte Standard (mg/l) Aluminum 0.05-0.2 Chloride 300 Copper 1 Fluoride 2 Iron 0.3 Manganese 0.05 ph 6.5-8.5 Silver 0.1 Sulfate 300 TDS 1,000 Zinc 5
Comparison to Historical Results Historical water quality data from TWDB Previous studies (TWDB reports, other reports)
FCGCD Results Primary Analytes Analyte TWDB Historic Range (mg/l) Range from Study (mg/l) Calcium 1-1,234 1.6-377 Magnesium 0.01-467 0.1-167 Potassium 1-258 0.7-28 Sodium 3-1,278 13-1,020 Iron ND - 18 ND - 168 Chloride 5-3,797 8-973 Fluoride 0.01-7 ND - 2.2 Sulfate ND - 1,664 ND - 1,430 Nitrate ND - 970 ND - 87 Total Dissolved Solids 50-8,186 198-3,710 Alkalinity, Bicarbonate ND - 1,147 ND - 898 ph 3.5-8.8 6.5-10.9
FCGCD Results Primary Analytes Analyte Drinking Water Standard Primary Secondary Range (mg/l) Number above DWS Calcium 1.6-377 --- Magnesium 0.1-167 --- Sodium 13-1020 --- Potassium 1-28 --- Iron 0.3 ND - 168 80 Fluoride 4 2 ND - 2 1 Chloride 300 8-973 36 Sulfate 300 ND - 1,430 36 Alkalinity, Bicarbonate ND - 898 --- Total Dissolved Solids 1,000 198-3710 62 Nitrate 10 ND - 87 4 ph 6.5-8.5 6.5-10.9 6
Analytes Detected Above DWS Numerous analytes exceeded applicable DWS Primary standard (MCL) Arsenic and nitrate Other analytes sporadically exceeded Secondary standards TDS, chloride, sulfate, iron, manganese Other analytes sporadically exceeded
Confirmation Sampling Detections in selected wells may be resampled to confirm presence of certain analyte(s) Done in coordination with the GCD and well owner.
Geographic Trends Assessment of data for trends- primarily TDS Geographic trends generally not discernable in PVGCD In FCGCD, attempted to determine downdip 1,000 mg/l TDS line
PVGCD Historic TDS
PVGCD Current Study TDS
FCGCD Jackson Aquifer TDS
FCGCD Yegua Formation TDS
Summary Successfully sampled 277 wells in Fayette County and 164 wells in DeWitt County Good distribution across study area and by aquifer system Results generally in line with historic TWDB data and/or previous studies Valuable data set to establish county-wide baseline for water quality Expands number of wells with historic data
Summary A few wells above primary drinking water standard (MCL)- arsenic, nitrate, chromium, fluoride, lead, selenium Numerous wells above the secondary drinking water standards - TDS, chloride, sulfate, iron, manganese - not unexpected
Summary Significant groundwater quality data collection studies being done by the state are at a much larger scale--will not have a lot of data in each county It is up to individual districts to collect and assess this data within their district This includes baseline water quality data and data to assess any unique issues a district may be concerned about
Questions?????