What can they teach each other? Geary M. Schindel, P.G. Chief Technical Officer Edwards Aquifer Authority San Antonio, Texas

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Jeremy Watkins
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1 Cavers and Geologists What can they teach each other? Geary M. Schindel, P.G. Chief Technical Officer Edwards Aquifer Authority San Antonio, Texas

2 Karst is a landscape where dissolution is the dominant geomorphic agent. It is characterized by sinkholes, sinking streams, caves, springs, and a well integrated subsurface drainage network d Neversink, North Alabama Dishman Lane sinkhole collapse, Bowling Green, Kentucky Photo Center for Cave and Karst Studies, Western Kentucky Univ.

3 Source: Living with Karst, AGI, 2002

4 Darcy s Law is the equation defining groundwater flow in equivalent porous media aquifers does it apply to karst? Q = KIA Jim Quinlan said the average caver knows more about groundwater flow in karst than most professionally trained geologists and engineers

5 Few colleges or universities offer specific course work in karst hydrology yet 20% to 30% of the US is karst and some states exceed more than 50%

6 Many karst aquifers contain unique biota Many were first brought to the attention of scientists by cavers

7 The cave maps produced by cavers often provide the basis for work by karst hydrologists, engineers, urban planners, biologists, environmental scientists, and regulators From Center for Cave and Karst Studies, Western Kentucky University Bowling Green, Kentucky

8 Cave maps often provide insight into the preferential flowpaths of a karst aquifer Honey Creek Cave, Comal County, Texas. Mapped length of cave is 19+ miles 1 mile Map provided by 1 mile Map provided by Kurt Menking, Bexar Grotto of NSS

9 W N E EDWARDS AQUIFER REGION S Drainage Area Artesian Zone KILOMETERS Location of the Edwards Aquifer in Texas

10 Figure 2 Cross Section of the Edwards Aquifer in Bexar County, Texas USA

11 Location of 2,000 gallon diesel fuel spill and Comal Springs - largest spring in western US with average discharge of 280 cfs Miles

12 Valdina Farm Sinkhole, Medina Co., Texas. A 150 foot pit and recharge feature. Picture above is during flood, picture to right is during normal conditions Catfish Farmer Well artesian well flowing at >30,000 gpm. Bexar County, Texas

13 Quarry wall in Edwards Limestone Recharge feature 60 foot pit Abandoned well used as toilet by homeless Swimming in the aquifer

14 Cave maps often provide an insight into the preferential flowpaths in a karst aquifer Mapped length is 6.7 kilometers 4th longest cave in Texas Source: Elliott and Veni, 1994

16 S ill it l t d dj t t Di l f l d i f l ti Spill site located adjacent to quarry. Diesel fuel used in formulation o explosives in quarry. Depth to groundwater is 280 feet

17 8 per Billion Parts Jan 20-Jan 25-Jan 30-Jan 4-Feb Date 8 lion Parts per Bill Jan 20-Jan 25-Jan 30-Jan 4-Feb Date Miles

18 Tracer Test Sampling Points Recharge Zone Comal Springs Fault Trace %U %U NBU Yard Eosine (Panther Canyon Well) Spring Run 3 r Spring 7 r Spring Island Landa Lake %U NBU Well 5 Golf Course Artesian Zone Old Channel Uranine (LCRA Landa Lake Outlet Well)

19 Eosine Breakthrough Curve on Filter Fluorometer at Spring Run rts per Billion Par Breakthrough at 2:04 pm 6 Injected at 11:37 am :00 AM 12:00 PM 3:00 PM 6:00 PM 9:00 PM 12:00 AM

20 Uranine Tracer Test Results in the Landa Park Area Uranine Eosine Y %U NBU Well 5 r Panther Canyon Well r LCRA Well Y

21 Breakthrough Curves at Landa Lake Outlet Intensity Eosine From Panther Canyon Well Comal Springs Discharge ( cfs) Uranine from LCRA Well Mar 23-Mar 24-Mar 25-Mar 26-Mar 27-Mar 28-Mar 29-Mar 30-Mar 31-Mar 1-Apr 2-Apr 3-Apr 4-Apr 5-Apr Uranine results indicate photodegradation of dye as it crosses Landa Lake

22 Comal Springs Tracer Test Estimated Travel Time Using Velocity Equation from Darcy slaw v = Ki/n T = 7,000 ft 2 /day from kriging gin BEG ROI 250 b = 500 feet (thickness) n = 0.3 porosity from BEG ROI 238 i = gradient = 0.01 ft/ft (21.7 feet of head over 2,000 feet) v= Ki/n = 0.47 feet per day or 11 year travel time from LCRA Well to Landa Lake actual time from tracer test data was 36 hours

23 Comal Springs Tracer Test Estimation of Conduit Size Using Continuity Equation A = Q/V A = Cross-sectional area in square feet Q = Discharge in cubic feet second (360 cfs) (50% of discharge from artesian zone) (50% of discharge from recharge zone) V = Velocity, feet per second (0.023 ft/sec for artesian zone) ( ft/sec for recharge zone)

24 Comal Springs Tracer Test Number of Conduits Diameter of Conduits Reynolds Number Diameter of Conduits Reynolds Number Artesian Zone Artesian Zone Recharge Zone Recharge Zone ft 212, ft 120, ft 63, ft 38, ft 20,937 6 ft 13,958 All Reynolds number are > 2,000; therefore, flow is turbulent and dd Darcy s Law does not apply to this portion of aquifer

25 Cavers and Geologists What is a caver? What is a karst specialist? Someone who is a member of the NSS, NSS CDS, or NACD How do you find a caver? Local chapters of the NSS can be found from the NSS web page at Someone through training and experience who has gained a certain level of competence in addressing karst problems. Currently, there is no certifications for specialists in the field of karst State cave surveys can usually be contacted through cavers? Most cavers are willing to help and commonly volunteer maps and assistance once they understand what you want Some states maintain a list of recognized experts in karst Professionals should seek out the opportunity to enter caves with cavers or taking specialized training in karst

26 Cavers and Geologists Cavers need to start considering Karst specialists need to treat themselves professionals and stop cavers with respect and stop thinking of themselves as looking at them as if they just someone who just crawled out crawled out from under a rock from under a rock Cavers don t realize the importance of their maps and observations Karst specialists don t realize the importance of the years of field work locating springs and mapping in many states Relationships with cavers need to be developed before you need them before the next big spill

27 Cavers and Geologists Cavers need to reach out to the State regulatory agencies and non-specialist consultants need to have access to karst specialists and use them Cavers need to learn for karst problems environmental regulations and reporting methods State surveys need to collect karst related data spring and cave locations, maps, contact names, etc.

LBJWC - Sinkhole Lesson

LBJWC - Sinkhole Lesson Concept Caves and sinkholes are major openings in the ground that recharge water to the Edwards Aquifer. Objective - Students will: 1) identify a sinkhole, cave, fracture, fault,