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Preliminary Results of Dye- Tracer Test at the B4 Area and Offsite Wells. Dye Injection 11/13/07 Results up to 1/8/08 (8 weeks). Sites with TCE detections. Rottenwood. Southern Polytechnic State University. Creek. MW0s2. 2000 Results Air Force Plant 6 Dobbins Air Force Reserve Base.
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Preliminary Results of Dye- Tracer Test at the B4 Area and Offsite Wells Dye Injection 11/13/07 Results up to 1/8/08 (8 weeks)
Sites with TCE detections Rottenwood Southern Polytechnic State University Creek MW0s2 2000 Results Air Force Plant 6 Dobbins Air Force Reserve Base B-4 Area Life University
Objective and Approach • Better understand ground-water movement in deep bedrock from B4 to offsite area • Selected two on-site wells (OB203 and RW203) that were located close enough to each other for an initial test. • Also included off-site bedrock wells in the test that were located downgradient from the injection well.
Sampling Frequency • Weekly sampling at RW203 • Monthly sampling at other sites
Pre-Injection Background Sampling • Fluorescein (Acid Yellow 73) • Eosine (Acid Red 87) • Rhodamine WT (Acid Red 388) • Sulphorhodamine B (Acid Red 52) • Tinopal CBS-X (Fabric brightening agent 351) • Solophenol 500% (Direct Yellow 96) • D&C Red #28 • FD&C Red #3 • D&C Green #8 • Palanil Luminous Red G • Lissamine FF
Injection 11/13/07 @ 1300 • Set 1-inch PVC to 90 ft • 1 gal #3 Red (pre-mixed) • Followed by 15 gal water (Flowmeter indicated no flow below 105 feet)
Downgradient Monitoring Well RW203 • Downward flow between 100 and 139’ • Zero flow below 139’ • Dye receptor placed at 105’
Results: Injection 11/13/07 @ 1300 ob203a RW203 SCT2 SCT1 SCT3 (65-95) (100) C (85-125) (139) C (88-105) B (434-457) B (119-198) A A (521-543) (420-560) 92’ 380’ 880’ Depths in parentheses (not to scale)
Results – 3 Days ob203a RW203 SCT2 SCT1 Not sampled Not sampled SCT3 (65-95) 30446 C (85-125) C (88-105) B (434-457) B (119-198) A A (521-543) (420-560) 92’ 380’ 880’
Results – 2 Weeks ob203a RW203 SCT2 SCT1 SCT3 (65-95) 22973 ND C ND (85-125) ND (.030) C (88-105) ? B (434-457) B (119-198) A A (521-543) (420-560) 92’ 380’ 880’
Results – 5 Weeks ob203a RW203 SCT2 SCT1 ND SCT3 (65-95) 6650 0.365 21.4 C (85-125) C (88-105) ND B (434-457) B (119-198) ND (.050) A ND A (521-543) (420-560) 92’ 380’ 880’
Results – 8 Weeks ob203a RW203 SCT2 SCT1 ND SCT3 (65-95) 201 15.6 300.2 C (85-125) C (88-105) B (434-457) B (119-198) ? (not sampled) A ND A (521-543) (420-560) .916 92’ 380’ 880’
What would cause such a highly constrained flow path?Why is the flow rate so high?
II IV III I-B I Dominate strike of foliation = green, joints = red
Findings (so far) • Fastest GW movement is through transition zone with flow rates on the order of 25 to 50 ft/day • GW movement appears to be strongly constrained along discontinuities formed parallel to foliation/layering (i.e. parting planes and lithologic contacts) • A downward hydraulic gradient in the area appears to influence deeper GW movement
Tracer Test Continued… • Stay tuned • Sampling every 3 weeks • Will continue to sample until dye passes through system or we are satisfied with results • Other zones/wells may be tested