Ground Water Pressure - Tensiometers
WARNING: Provisional Data, subject to revision
Since late October 2006, the Portland Hills site has been equipped with seven tensiometers arranged in two arrays or nests. The tensiometers (UMS Corp. Model T-8)* are equipped with current transducers that can measure pressures in the range from +850 hPa to -1000 hPa (suction) and accuracy of ±5 hPa are installed in boreholes that are inclined from 20° to 35° from the vertical, to facilitate refilling. The porous tips are at depths ranging from 73 to 220 cm below the ground surface. Pore pressures are reported in hectoPacsals (hPa). One hectoPascal is roughly equivalent to the pressure exerted by a 1-cm-high column of water. Porous tips of the tensiometers are in direct contact with native soil.
| Tensiometer Number | Depth below surface, cm | Inclined distance from tensiometer tip to ground surface, cm |
|---|---|---|
| I-1 | 206 | 178 |
| I-2 | 155 | 134 |
| I-3 | 91 | 79 |
| I-4 | 164 | 143 |
| I-5 | 92 | 80 |
| I-6 | 220 | 194 |
| I-7 | 73 | 63 |
Soil suction/pore pressure at upper tensiometer nest, last 4 days
Soil suction/pore pressure at lower tensiometer nest, last 4 days
Long-term soil suction at all tensiometers
Recent Tensiometer measurements, daily median
| Date | TENS1, hPa | TENS2, hPa | TENS3, hPa | TENS4, hPa | TENS5, hPa | TENS6, hPa | TENS7, hPa |
|---|---|---|---|---|---|---|---|
| 4/12/2008 | 10.987 | 4.5609 | -821.42 | -58.014 | -62.072 | -24.190 | 1000.0 |
| 4/13/2008 | 11.522 | 6.1056 | -260.31 | -60.244 | -66.338 | -24.361 | 1000.0 |
| 4/14/2008 | 10.665 | 3.8937 | 300.83 | -63.823 | -69.240 | -27.256 | 1000.0 |
| 4/15/2008 | 10.156 | 0.67731 | 161.14 | -65.673 | -72.105 | -28.774 | 1000.0 |
| 4/16/2008 | 9.8142 | 2.3692 | -6999.0 | -65.313 | -73.434 | -28.088 | 1000.0 |
| 4/17/2008 | 9.6112 | 4.5340 | -6999.0 | -65.531 | -77.716 | -27.960 | 1000.0 |
| 4/18/2008 | 9.8207 | 7.1116 | -6999.0 | -66.712 | -80.934 | -28.107 | 1000.0 |
| 4/19/2008 | 9.4818 | 5.0795 | -6999.0 | -69.421 | -82.967 | -30.816 | 1000.0 |
| 4/20/2008 | 8.6365 | 2.5421 | -6999.0 | -71.268 | -86.166 | -31.993 | 1000.0 |
| 4/21/2008 | 8.1248 | 2.7084 | -6999.0 | -71.090 | -87.339 | -31.821 | 1000.0 |
| 4/22/2008 | 7.5937 | 4.2090 | 999.32 | -70.932 | -87.179 | -31.669 | 1000.0 |
| 4/23/2008 | 6.0937 | -3.7240 | -6999.0 | -75.152 | -90.047 | -35.883 | 1000.0 |
| 4/24/2008 | 6.0937 | -3.3850 | -6999.0 | -75.152 | -92.755 | -34.529 | 1000.0 |
| 4/25/2008 | 6.4301 | 0.33868 | 999.66 | -76.142 | -97.800 | -34.856 | 994.59 |
| 4/26/2008 | 7.0211 | 4.9918 | 1000.0 | -76.854 | -103.91 | -33.564 | 1000.0 |
| 4/27/2008 | 7.5334 | 6.1803 | 1000.0 | -79.062 | -110.18 | -34.411 | 1000.0 |
| 4/28/2008 | 7.7838 | 7.7838 | 1000.0 | -80.880 | -114.04 | -35.533 | 1000.0 |
| 4/29/2008 | 7.4478 | 3.3855 | -6999.0 | -83.954 | -115.78 | -38.591 | 1000.0 |
| 4/30/2008 | 6.7707 | 0.18311E-03 | -6999.0 | -85.985 | -118.15 | -40.284 | 1000.0 |
| 5/01/2008 | 7.5936 | 3.8716 | -6999.0 | -85.793 | -122.68 | -39.100 | -6999.0 |
| 5/02/2008 | 7.4427 | 2.7065 | -6999.0 | -88.633 | -127.20 | -41.272 | 1000.0 |
| 5/03/2008 | 7.2465 | 2.1693 | -6999.0 | -89.896 | -129.16 | -42.510 | -6999.0 |
| 5/04/2008 | 7.7309 | 2.9962 | 939.12 | -91.023 | -133.64 | -42.322 | 1000.0 |
| 5/05/2008 | 7.4427 | 0.67682 | 998.65 | -94.384 | -140.05 | -44.655 | 1000.0 |
| 5/06/2008 | 7.1069 | -1.6920 | -6999.0 | -96.446 | -143.15 | -46.362 | -6999.0 |
| 5/07/2008 | 6.3096 | -2.4900 | 617.21 | -97.933 | -146.67 | -47.166 | -6999.0 |
| 5/08/2008 | 6.1827 | -1.2640 | 999.32 | -99.427 | -151.56 | -47.976 | -6999.0 |
| 5/09/2008 | 5.4129 | -0.67603 | -6999.0 | -101.49 | -156.29 | -48.714 | 1000.0 |
| 5/10/2008 | 3.7228 | -3.0450 | -6999.0 | -103.55 | -160.07 | -51.776 | -6999.0 |
| 5/11/2008 | 3.5237 | -5.9540 | -6999.0 | -106.14 | -165.38 | -53.340 | -6999.0 |
