Ground-water development in East St. Louis area, Illinois. Urbana, IL ...

More documents

Recommendations

Info

wells contain slotted pipe screens. Irrigation wells range in diameter from 8 to 16 inches and usually have pack thicknesses of 6 to 8 inches. Lengths of slotted pipe screens range from 10 to 40 feet. Service Life of Wells and Collector Wells One of the problems in the East St. Louis area associated with the development of ground-water resources is the short life expectancy of wells. According to a study by Bruin and Smith (1953), the median service life of municipal wells terminating in sand and gravel formations in the East St. Louis area is about half that for similar municipal wells in other parts of the state. Nearly all of the wells retired in the area were taken out of service either because the screens had become partially clogged or the wells had filled with sand. The results of mechanical analyses presented by Bergstrom and Walker (1956) are shown in figures 26 through 28. According to Bergstrom and Walker the analyses must be accepted with caution because the conditions of collecting most of the samples are not known, and because of the highly variable nature of the valleyfill deposits in the area. A careful examination of the mechanical analysis curves suggests that the valley-fill deposits contain a rather high percentage of fine materials which could, under heavy pumping conditions, migrate toward a screen and partially clog the well wall and screen openings. As indicated by data in the files of industries and municipalities, specific capacities of existing production wells decrease markedly after a few years and in some cases after a few months of operation. Specific capacities are generally determined by the driller after completion of the well by pumping the well at different rates for short periods of time, generally less than 24 hours, and by frequently measuring drawdowns in the pumped well. This method of measuring specific capacity is continued by industrial and municipal personnel periodically. It is a general practice of industries and municipalities to place a well in operation and pump it at high rates, often about 1000 gpm. As the result of heavy pumping, fine materials migrate towards the well and partially clog screen openings and the voids of the formation surrounding the well. The well-loss constant increases rapidly and, because well loss varies as the square of the discharge rate, drawdown increases rapidly. The relation between well-loss constant and drawdown due to well loss is shown in figure 29. As drawdown increases the specific capacity and, therefore, the yield of the well decreases. Typical decreases in specific capacity due to increases in the well-loss constant are given in table 19. Theoretical specific capacities of wells with a nominal radius of 15 inches and with 40 feet of screen given in table 19 were determined for values of the coefficient of transmissibility ranging from 100,000 to 300,000 gpd/ft, Figure 26. Mechanical analyses of samples from wells 27
a coefficient of storage of 0.10, a pumping period of 12 hours, pumping rates of 900 or 450 gpm, well-loss constants of 1, 5, and 10 sec 2 /ft 5 . The effects of dewatering and partial penetration (see Walton, 1962) were taken into consideration in computations. Computed well-loss coefficients for wells tested immediately after construction (table 14) range from 0.2 sec 2 /ft 5 to 1.0 sec 2 /ft 5 and meet requirements suggested by Walton (1962) that the value of G of a properly developed and designed well should be less than 5 sec 2 /ft 5 . According to Walton (1962), values of C between 5 and 10 sec 2 /ft 5 indicate mild deterioration, and clogging is severe when C is greater than 10 sec 2 /ft 5 . It is difficult Figure 27. Mechanical analyses of samples from wells Figure 28. Mechanical analyses of samples from wells 28
Page 2 and 3: REPORT OF INVESTIGATION 5I Ground-W
Page 4 and 5: CONTENTS PAGE Abstract Introduction
Page 6 and 7: FIGURE PAGE 47 Water levels in Gran
Page 8 and 9: Ground Water Development in East St
Page 10 and 11: Csallany, W. H. Walker, T. A. Prick
Page 12 and 13: Figure 2. Drainage system and locat
Page 14 and 15: at St. Louis was 421.26 feet and oc
Page 16 and 17: Figure 5. Thickness of the valley (
Page 18 and 19: Table 6 (Continued) Sand, very coar
Page 20 and 21: An aquifer test was made October 25
Page 22 and 23: elief wells 137 and 139. Water leve
Page 24 and 25: is intercepted and the cone is deep
Page 26 and 27: straight line per log cycle and the
Page 28 and 29: Figure 20. Time-drawdown data for w
Page 30 and 31: Table 15. Specific-Capacity Data fo
Page 32 and 33: Table 17. Pumping center Pumping Ce
Page 36 and 37: city of Wood River is given in figu
Page 38 and 39: a test hole near Monsanto. The coef
Page 40 and 41: Figure 35. Estimated pumpage, Alton
Page 42 and 43: dition, industrial and urban expans
Page 44 and 45: River stages were higher in June 19
Page 46 and 47: of the drought and changes in river
Page 48 and 49: The general pattern of flow of wate
Page 50 and 51: Table 23 (Continued) Water level ch
Page 52 and 53: Figure 54. Approximate elevation of
Page 54 and 55: RECHARGE FROM INDUCED INFILTRATION
Page 56 and 57: Table 27. Results of Aquifer Tests
Page 58 and 59: Potential recharge by the induced i
Page 60 and 61: The model was developed on the prem
Page 62 and 63: tions 26 and 28 which relate electr
Page 64 and 65: Figure 62. Areas of diversion in No
Page 66 and 67: water levels due to the changes in
Page 68 and 69: Table 35. Potential Yield of Aquife
Page 70 and 71: Table 37. Chemical Analyses of Wate
Page 72 and 73: Table 37 (Continued) Sodium Alka- H
Page 74 and 75: Table 39 (Continued) Total Laborato
Page 76 and 77: REFERENCES Ahrens, T. P. 1957. Well

Ground-water development in East St. Louis area, Illinois. Urbana, IL ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?