TEST, NEW SIDNEY WTERWORKS DISTRICT WELL NcTAVISH ROAD

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Justin Webster
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1 '&.d' REFIR T ON F"ING TEST, NEW SIDNEY WTERWORKS DISTRICT WELL NcTAVISH ROAD On December loth, 1963, a 24c;ho~r punping test was run on a new well drilled by Pacific Water Wells for the Sidney Waterworks District. The test was supervised by the Groundiwater Division of the Water Resources Service at the request of John Mothemll in his letter of December 6th, Pacific Water Wells supplied a. small pump for the job and a water level indicator for use in the large well. Pacific abo supplied well points for each of two observation wells which were originally drilled as test holes with an auger. These holes, OH1 and OH2 are located 36.6 feet and 83.2 feet fmm the centre of the new well. The log of the new well shows 9 feet of clay over 22 feet of sand. The sand is underla,in by silty clay. The test holes show that the same become thinner to the north. The new well was drilled 12 inches in diameter to the bottom of the aqu5fer at 31 feet. It is equipped with 18 feet of 8 inch diameter well screen with,06it slots and a gravel pack of material sold as chicken grit. This gravel is crushed diorite; the grains are predominantly angulas. The test was not entirely successful in that one of the observation wells (Om) did not work at all while the other (OH2) was partially plugged making some of the data useless. The observation wells were put in immediately before the start of the test and both were almost entirely plugged. Both were =,shed out wtth a hose; water under pressure was then washed through them until sand was brought to surface outside of the casings. After this, the water in these wells went down slowly to static level, showing that they were not plugged. More time would have been spent on this but for the fact that the test was being delayed, However, settlement of sand and clay around the well points, which were not much below the bottom of. the clay, completely plugged OH1 and par tially blocked OH2. It should immediately have been apparent tha,t OH1 was not working as the drawdown of OH2 soon became greater than that of OH1 which is.jmpossible under the conditions of the test. I failed to notice this until the test was almost over so the data from OH1 had to be discarded. When the data for OH2 are plotted as drawdown (s) versus t/time since start (l/t) the early part of the curve where drawdown is quite rapiddoes not have the chara.cteristic shape indicating that the partially blocked observation well was not able to keep up with the rapid drawdown. The data wen? analyzed by several methods. non-equilibrium equations we get: T = 8,000 gal/day/ft,width (U.S.) s =,0026 Using the standard Using Van Te Chow's method, we get: T = 8600 gal/day/ft.width S e0027 (U.S.) Using the Theis recovery method on dabta from the recovery of the pumped well, we get: T = 13,500 galbday/ft.width (U.S.) Using Jacob 8s modified non-equilibrium method, we get : T = 9,200 gal/da.y/ft.width s -,0023 (US.)

2 All of these results are in the same order. If the data obtained had been of higher quality, these aquifer characteristics would probably have been in closer agmernent, These results indicate that the theoretical drawdown at the well after one day of pumping is in the order of 8 feet showing that the actual drawdown in the well of about 11% feet is not excessive. The well construction therefore is satisfactory and similar well construction should be used in future wells. Use of rounded gravel in the gravel pack instead of the chicken grit might improve the efficiency of the well. I E+y using the aquifer characteristics and making certain assump tions, it is possible to predict the drawdown after prolonged pumping. Since two of the assumptions namely infinite aquifer extent and uniform aquifer thickness are definitely not true in this case, this should not be done. From the results of the test, we believe that a capacity for this well of 40 Imperial gallons per minute is indicated. - Two wells on this piece of property located as far from each other as possible would certainly yield more water than the present well although not twice as much. There a m two things to be consideed in planning an additional well here, First, the test holes indicate thinning of the aquifer northward although this trend may not continue to the north end of the lotn Second, a well on the north boundary of the lot will certainly interfere with the nearby spring which supplies water to several houses in that area. In considering drilling on the property near the old Sidney wells (near Gray s well) several things should be kept in mind. For preliminary test holes, the power auger may not be suitable as logs in this area show till between the clay and the underlying aqulfer. In any case, more care should be taken in installing some sort of casing in such holes for use as observation wells during a pump test - to avoid the trouble encountered in the test described above. E. Livingston Geological Engineer.....

3 11 11:E ll:12$ ll:13 11 :l4 U:15 ll:16 U:17 ll:18 11:19 U:20 ll:24 ll:25 Ut26 11~29 U:30 IJ. :33-35 u, :36 n:37 U:38 ll:40 ll:t!&l Ut43 u.:45 n:46 U:48 U:5O ll.$1 ll:52 u:55 11$6 us9 12t00 Noon 12 :02 12 :Oh 12 to4 12 :08 l2:lo 12 :15 12 :17 12 :20 12 :23 12 :25 12:27 12:29 12 :30 12:31 12 :32 12 :34. 12:u 12 t44 12:45 12 :47 12 $1 12 : $9 13:OO 13 :02 13 :04 13 :u. 13 :i7 13 :18 ; NEW WEZL FUMPING TEST, McTAVISH RilD,., DD DD Time since start min. 0 l l u ll0 u2 ll Well SL = e20.009l5 eoo9l.o eoo825 e OH2 1.19?.lO& le e le ,08 2 n 2 el e e35 2 e37 2.bo 2.b2 2 e44 2 e e e e e e87 2 e e93 3.b3 b DD 0h2 0 Start e e66 e e 78 e80 e-85 e e le e71 Remarks Increase pump rate

4 . -2- \ * start 13;24 13 :25 13 :30 13 :32 13 :35 13 :45 13 :b9 13:59 14:oo 4:06 l4 =15 l.4: :30 a:33 l4:46 15 :oo 15 :01 15 :16 15:30 9ims since min : : : : :lO i : :43 17:OS l l : : : :kO 18 :02 u2 18 : :18 18 : :50 19:OO : : l9:so : : : l!: : :oo :oo : O:OCauIidnight 770 1:OO :oo 950 4:OO :m :OO :OO : : : lot :oo u:15 l445, ll a e00173 ll a A DD OH billaxks 2.40 Spring stopped Cormeted DODO Well ll U.58 U

5 Time U. : :19 11 :I# u:20 11:21 u:22 u.:23 ll:24 ll:25 U:26 U:27 ll:27$ llt28 ll:29 U:30 11 :33 u.:34 =:35 ut36 11: 37 ll:39 U:40 1l:U 11 :42 =:45 U:46 u:47 11:50 U:51 ut52 11 :52* :55 65% ll:58 12 :oo 12 :05 12 :06 12 : :20 u :38 12 :40 12 :u 12 r45 12 $6 13 :08 13 :OP$ 13 :ii 13 :13 13:s 13 :17 13 :l9 13 :21 13 :23 t Tinns Since Stark U :27 13 : 33 13& : ~ :OO 1610 &: :lO 1620 a: : : :OO Draw down t Well a O l Ol% Y'Q t' Time Since DD Stop OH2 OH2 En, l Spring overflow & Recorder removed 17 e % Reading taken 3PM Dece&er 12th

On The Determination of Transmissibility and Storage Coefficients from Pumping Test Data

Circular No. 38 1952 STATE OF ILLINOIS On The Determination of Transmissibility and Storage Coefficients from Pumping Test Data Issued by Department of Registration and Education C. HOBART ENGLE, Director