WEBVTT Kind: captions Language: en 00:00:00.290 --> 00:00:08.370 Introduction Hi, I’m Jesse Dickinson, a hydrologist with 00:00:08.370 --> 00:00:09.740 the US Geological Survey. 00:00:09.740 --> 00:00:14.240 We’re here in the San Pedro Basin in Southeastern Arizona, and we’re going to demonstrate 00:00:14.240 --> 00:00:16.610 how to measure hydraulic head in an artesian well. 00:00:16.610 --> 00:00:18.620 Materials: The materials needed include: 00:00:18.620 --> 00:00:23.320 A pipe wrench, A plug for the well, A clear plastic column that can be attached vertically 00:00:23.320 --> 00:00:27.720 to the opening of the well , Plumbers tape to ensure a tight fit to the well and to minimize 00:00:27.720 --> 00:00:32.260 leaking, A pencil or pen if using a water level field form, or a device for electronic 00:00:32.260 --> 00:00:36.930 data entry, A ruler or tape for measuring the height of water in the plastic tube, A 00:00:36.930 --> 00:00:40.480 level to ensure that the ruler or tape is perpendicular to the land surface 00:00:40.480 --> 00:00:43.560 Instructions: Step 1) Determine you are at the correct well 00:00:43.560 --> 00:00:47.940 from the well description and locate the documented measuring point(s) and land surface datum 00:00:47.940 --> 00:00:50.030 from well photo or diagram. 00:00:50.030 --> 00:00:55.150 Step 2) If necessary, use a pipe wrench or other tool to remove any plugs in order to 00:00:55.150 --> 00:00:57.430 gain access to the well. 00:00:57.430 --> 00:01:02.810 Step 3) Apply plumbers tape to ensure a tight fit between the well opening and the plastic 00:01:02.810 --> 00:01:05.010 pipe to minimize leaking. 00:01:05.010 --> 00:01:10.460 Step 4) Connect a length of transparent plastic pipe tightly to the well. 00:01:10.460 --> 00:01:14.360 Step 5) Gradually close any other opening to the flowing well. 00:01:14.360 --> 00:01:18.610 If pressure is applied suddenly, the well could be permanently damaged by the “water-hammer 00:01:18.610 --> 00:01:23.670 effect” by caving of the aquifer material, breakage of the well casing, or damage to 00:01:23.670 --> 00:01:25.990 the distribution lines or gauges. 00:01:25.990 --> 00:01:30.710 Step 6) Ensure that all flow from the well stops so that a static water-level measurement 00:01:30.710 --> 00:01:32.170 can be made. 00:01:32.170 --> 00:01:36.920 Step 7) Rest the ruler or measuring tape on the measuring point (MP) and use the level 00:01:36.920 --> 00:01:40.960 to check that the ruler or tape is perpendicular to the land surface. 00:01:40.960 --> 00:01:44.810 Use the scale to read the height above the measuring point that the water has risen in 00:01:44.810 --> 00:01:46.300 the plastic pipe. 00:01:46.300 --> 00:01:51.520 Step 8) Record the date and time of the measurement on a Water Level Measurement Field Form or 00:01:51.520 --> 00:01:53.409 a digital screen input form. 00:01:53.409 --> 00:01:57.970 Because the water level is above the measuring point, this is a negative number. 00:01:57.970 --> 00:02:03.189 Step 9) Record the measuring point (MP) correction length on the “MP correction” row of the 00:02:03.189 --> 00:02:07.940 field form or select the MP used from the electronic data entry form. 00:02:07.940 --> 00:02:12.709 Subtract the MP correction length from the true “water level below measuring point” 00:02:12.709 --> 00:02:17.959 value to get the depth to water above the land surface datum as a negative number. 00:02:17.959 --> 00:02:23.680 The MP correction is positive if the MP is above the land surface, or negative if it 00:02:23.680 --> 00:02:25.689 is below the land surface. 00:02:25.689 --> 00:02:31.379 On the field form, record the water level in the “WL below LSD” column. 00:02:31.379 --> 00:02:35.620 Step 10) Make a check measurement by performing the previous steps. 00:02:35.620 --> 00:02:39.400 Record the check measurement on the field form or electronic data entry form. 00:02:39.400 --> 00:02:42.909 If the check measurement differs from the original measurement by greater than 0.1 or 00:02:42.909 --> 00:02:49.069 0.2 foot, continue to measure the water height until the reason for a lack of agreement is 00:02:49.069 --> 00:02:52.489 determined or the results are found to be reliable. 00:02:52.489 --> 00:02:58.230 Complete the “final measurement for GWSI” portion of the paper or digital field form. 00:02:58.230 --> 00:03:01.980 Step 11) Gradually remove any plugs to the flowing well. 00:03:01.980 --> 00:03:06.469 If pressure is applied or released suddenly, the well could be damaged. 00:03:06.469 --> 00:03:10.659 Step 12) Remove the clear plastic pipe from the opening of the well. 00:03:10.659 --> 00:03:14.129 Step 13) Attach any other plugs to well openings. 00:03:14.129 --> 00:03:16.569 Limitations: Keep in mind the following limitations of 00:03:16.569 --> 00:03:17.969 this method. 00:03:17.969 --> 00:03:22.139 Low-pressure head measurements are most feasible when the head is less than six feet above 00:03:22.139 --> 00:03:23.579 the land surface. 00:03:23.579 --> 00:03:26.559 Measurements are commonly accurate to 1/10th of a foot. 00:03:26.559 --> 00:03:30.629 All flow from the well should be shut down so that a static water level measurement can 00:03:30.629 --> 00:03:31.629 be made. 00:03:31.629 --> 00:03:35.900 However, the time required to reach a static pressure after flow discontinues may range 00:03:35.900 --> 00:03:37.439 from hours to days. 00:03:37.439 --> 00:03:41.969 Since a true static measurement may be impractical, record the time after shutting off the flow 00:03:41.969 --> 00:03:43.540 for each measurement. 00:03:43.540 --> 00:03:45.980 Advantages: An advantage of a method for low pressure 00:03:45.980 --> 00:03:51.680 measurement is that it is generally simpler, faster, safer, and more accurate than a method 00:03:51.680 --> 00:03:53.029 for high pressure measurement. 00:03:53.029 --> 00:03:55.439 Disadvantages: A disadvantage is that this method may be 00:03:55.439 --> 00:03:59.469 impractical for wells with heads greater than 5 to 6ft above the land surface.