ARCHIVED REPORTS UIC PERMIT APP - Laserfiche WebLink

Home Browse Search

ATTACHMENT A:AREA OF REVIEW METHODS TABLE A-6 Zone of Endangering Influence Calculations Summary(425 gpm) r radius of endangering influence from injection well (ZEI),ft 4,219 ft(0.8 miles) K hydraulic conductivity of the injection zone, ft/day 5.91 E-01 ft/day H thickness of the injection zone,ft 230 ft t 3,650 days (10 years), 10,950 duration of injection, project life, days days (30 years) S storage coefficient, dimensionless 6.00E-04 Q injection rate,ft3/day 81,813 ft3/day(425 gpm) Pallowable Allowable Pressure Increase 175 psi (403 ft) Based on the conservative assumptions for parameter values and injection rates and durations, the total radius suggested by the above equation is 0.8 miles based on 10 years of injection. For 30 years of injection,the same calculation results in a radius of 1.4 miles. Summary of Area of Review Calculations Each of the AOR calculation methodologies considered that the fully permitted injection rates for the STIG-1 (200 gpm) and LEC-1 (225 gpm) wells were achieved 24 hours per day, 365 days per year for the next 30 years. In reality,this rate of injection is not expected to occur.For example,the STIG facility is a'peaker plant' -it provides power during periods when demands are high and supplemental power sources are needed. Consequently, the plant often does not operate during the winter months and even when the plant is operating,the injection well does not operate 24 hours per day. Based on review of the historic operation of the STIG-1 well since it began routine operation in 2000,the well has injected a total of 71.5 million gallons. This is approximately 10 percent of the potential maximum 788 million gallons the well could have injected between January 1,2000 and July 31,2008. Even at its peak year of operation in 2001 during the California Energy Crisis, STIG-1 injected 29.9 million gallons,approximately 28 percent of its potential capacity. Although it is unknown what rate the STIG-1 will operate at in the future, operation 100 percent of the time is not expected. The LEC plant is a baseload plant and is expected to have an operation that is closer to its potential than the STIG plant. Considering periodic maintenance and periods of lower energy demands,a conservative assumption of 90 percent operation is possible. Based on the calculations summarized in this attachment,the injection front is expected to travel less than 1,800 feet from the injection well,including the historic STIG-1 injection and estimated dispersion. This extends the area of fluid migration to beneath the adjacent City of Lodi property (Appendix 3). These calculations assume 24 hour per day,365 days per year of injection for 30 years at 425 gpm. Additionally,the pressure increase caused by the injection activities extends well beyond the front of injected fluid. Because the initial pressure of the injection formation is nearly hydrostatic,close to the same pressure as the USDW in the area, small increases in pressure expand the ZEI to large distances as shown using the modified Theis calculation above. However,the full formation thickness of the SAC/371322/082550016(ATTACH MENT-A.DOC) A-7