Drilling Summary (to be updated):

GPS Locations: 41.236535N, 105.455492W
GPS datum: NAD83

To understand aquifer recharge in the Laramie Basin, we have drilled and are currently installing two groundwater monitoring wells (“Government Gulch-Mon.1” or GGMW1 and “Government Gulch- Mon.2” or GGMW2) that are designed to document and quantify the timing, magnitude, and mechanics of recharge to the Casper Aquifer and underlying fractured granite. The wells are located on USFS land in Sections 27 and 34 of Township 15 North, Range 72 West, in the bottom of an unnamed drainage immediately south of the Government Gulch drainage. The two wells have a separation distance of only 7 feet. Below, the results of the drilling operation are described for each well.

GGMW1 was drilled and constructed by Watson Well Service from July 13 - 20, 2017, using air-percussion hammer (T-450 Schramm).  7 7/8-inch diameter borehole was advanced through the lower part of the alpha member of the Casper Formation, Fountain Formation, and into the upper 25 feet of the Sherman Granite to a total depth of 188 feet. Drilling behavior and air-lift production were noted during drilling and cuttings were collected at 10 foot intervals.  Cuttings were bagged and are available for more detailed inspection. The well was completed as a multi-level piezometer with three 1-inch diameter PVC casing/screens set in the Casper (40-60 ft bgs), Casper/Fountain (82-102 ft bgs), and Fountain (125-145 ft bgs). On July 25-26 there was a fairly substantial rain event in Laramie. On the morning of July 27, the water level in the 40-60 piezometer was 18.4 ft bgs whereas the water level in the 82-102 piezometer was 18.8 ft bgs.  The head increase in the 40-60 piezometer relative to the 82-102 piezometer (compared to similar heads measured on July 24) may indicated a relative response to recharge and/or barometric pressure.  Subsequent head monitoring will provide insight into processes responsible for different head responses in these piezometers.

GGMW2 was drilled by Watson Well Service from July 22 – 26, using air-percussion hammer in the cased portion and air-rotary in the open hole portion.  10-inch diameter borehole was advanced through the lower part of the alpha member of the Casper Formation, Fountain Formation, and into the upper 25 feet of the Sherman Granite to a total depth of 188.  5-inch PVC casing was set at 188 and chip bentonite installed from 75-188.  During placement, the chip bentonite bridged at 20 which prevented the placement of bentonite from 20 to 75.  Chip bentonite placement continued from 20 to ground surface.  Below the casing, 4 ¾-inch open hole was drilled in the Sherman Granite from 188 to 377.  Drilling behavior and air-lift production were noted during drilling and cuttings were collected at 10 foot intervals.  Cuttings were bagged and are available for more detailed inspection. While withdrawing out of the hole at 377 drilled depth, the driller noticed water cascading into the well at a depth of 47.  Apparently, holes or cracks developed in the casing during drilling, presumably focused in the section of casing annulus that did not receive bentonite seal (i.e. 20 to 75).  Consequently, water production estimates during drilling and current water level measurements are not representative of the Sherman Granite.  Brad Carr is currently running downhole tools into the well to better ascertain the location and character of casing compromises to help guide well rehabilitation efforts and to identify monitoring interval(s) in the Sherman granite.  One suite of logging was recently completed by Brad and he plans to re-log the hole on the coming Tuesday, 9/5/2017. The planned rehabilitation and the completion of this well will likely take place approximately in early to mid September, 2017. 

Detailed well logging in GGMW2 suggest these fracture intervals in the granite that produce water to the hole (all depths are bgs):
1) 58.73 m – 64.80 m
2) 66.08 m – 71.11 m (best one part at 68.40m)
3) 85.75 m – 88.45 m
4) 92.25 m – 95.76 m
5) 100.72 m -- 105.90 m
6) 109.00 m – 110.50m (lower priority in mud)

The Gamma Ray & Electromagnetic/Magnetic Susceptibility/Optical & Acoustic Televiewer determined geologic intervals (all depths are bgs):

1) 0 m – 31.66 m (Casper Fm.) (~104 ft. thick)
2) 31.66 – 45.44 m (Fountain Fm.) (~45 ft. thick)
3) 45.44 m – 55.16 m (Granite Saprolite) (~32 ft. thick)
4) 55.16 m – TD @ 115.09 m (as of 9/5/17 – the borehole is open to 110.3 m, i.e. currently 5.21 m (~17.1 ft) of infill).

a. 55.16 m – 88.72 m (“Red” FeS2 - Sherman Granite)
b. 88.72 m – 110.3 m (“Pink”, Normal – Sherman Granite)

5) Dykes within the “granite” interval:

a. 62.86 m
b. 63.20 m
c. 82.52 m
d. 84.00 m
e. 85.59 m
f. 86.24 m – 86.51 m
g. 88.32 m – 88.53 m
h. 88.71 m
i. 92.15 m – 92.24 m
j. 101.09 m – 101.27 m
k. 104.05 m – 104.15 m
l. 105.62 m
m. 109.3 m – 109.52 m

At GGMW2, we’ve drilled into red granite with underlying “regular, pink” Sherman, with various mafic and granitic dykes cross cutting the units. Interestingly, there is a lot of clay/fine material in the hole that is “glued’ in a sense to the mafic dykes. It may be the evidence that we were looking for in regards to the source of weathering fines/clays in the granite holes at Blair-Wallis.

Fall (exact date: ask Watson Wells), 2017:

In the granite well,  Watson emplaced a 2” PVC inner sleeve that was grouted in place to plug the holes in the original 5” PVC casing. The 2'' PVC is screened at the depth interval of 65.5-71.6 m (best water production part logged by Brad Carr). To confirm this information, need to reach out to Chris for the completion logs.

December 1, 2017:

Today, I installed transducers and started long-term datalogging at the Summit wells:

1.  Casper-shallow

Depth to water is now 32.15 ft., i.e. down 4 ft. over the last two months; 2 ft. in the last month.  Due to the close connection between this and the “Casper-deep” piezometer, no datalogger has been installed in this well.

2.  Casper-deep

Depth to water is now 32.15 ft., i.e. down 4 ft. over the last two months; 2 ft. in the last month.  Although one of the communication cables is 50 ft. long (the other is 30 ft.), to ensure water-level measurements if the water level continues to fall, the transducer has been hung on a wire - 70 ft. long + transducer body = 70.58 ft. below top-of-casing.

This log is called “GG_Casper_deep”, set up for 15-minute recording of psi, meters of water, and oC; started 12/1/17 at 10:45:00 MST.  All transducers were synchronized to the same time.

3.  Fountain

There is no indication of water leakage from the sealed wellhead, although there appears to be water up against the air valve.  There is very little room to work within the guard casing, but it is possible to get a modified air pump onto the air valve.  A small volume of air was added.  Conclusion: at worst, the wellhead (inside the 1" PVC) is now filled with ice and we may see evidence of water leakage when things thaw out next spring; at best, there is a small amount of ice in the wellhead, but it is not sufficiently confined to break anything.  In either case, absent water leakage, the pressure measurements remain valid.

Due to the confusion about cable lengths, the cable in this well is 50 ft. (rather than 30 ft.), so the 30 psi transducer is near the top of its range - currently reading 26.7 psi (i.e. 11.7 ft. above TOC, perhaps a small decline since the previous estimate).  This provides plenty of room to monitor declining water pressure, but only about 8 ft. to monitor rising pressure.  What happens if the nominal pressure rating is exceeded?, e.g. continues reading, but with reduce accuracy? or “pegs” out at 30 psi?

This log is called “GG_Fountain”, set up for 15-minute recording of psi, meters of water, and oC; started 12/1/17 at 10:00:00 MST.  All transducers were synchronized to the same time.

4.  Granite

Depth to water is now 171.61 ft. (TOC), i.e. up 11 ft. over the last month.  Whether this is the result of continuing recovery from construction work in this very-low permeability section, or represents natural fluctuations should be revealed through the long-term monitoring.

The transducer in this well has been hung on a wire - 210 ft. long + transducer body = 210.58 ft. below top-of-casing.

This log is called “GG_Granite”, set up for 15-minute recording of psi, meters of water, and oC; started 12/1/17 at 10:00:00 MST.  All transducers were synchronized to the same time.

5.  Barologger

Although this unit has been recording since November 4, that log was set to oF.  For consistency with the other logging, that log was stopped and a new log started.
 
This log is called “GG_Barometer”, set up for 15-minute recording of psi and oC; started 12/1/17 at 10:30:00 MST.  All transducers were synchronized to the same time.

Next Steps:

- Depending on the results recorded over the winter, it may be necessary to re-set the Fountain transducer depth to allow monitoring the full range of pressure.  This will require installing a new cable seal (i.e. with less cable hanging in the hole), which can be done in the same manner as the first.

- At some point, a slug test of the granite piezometer may be desireable.  Given its apparent low permeability, simply adding a few feet of water and monitoring water level decline may be sufficient.

- If experience indicates depth-to-water will not fall below 50 ft. in the Casper piezometer, the hang wire should be replaced with the 50-ft communication cable for convenience in recovering data.

- The condition of the Fountain piezometer “wellhead” should be monitored periodically to assess freezing issues and replaced if necessary. 


Below are DTW measurements from the top of the PVC casing at the marked locations; The measurements were done with Seth's e-tape, which has 1/500 ft of error.

2/28/2018; 3 pm MST;  Field trip with Seth Davidson (USGS) and Shawn (UG assistant);
  Granite:                            161.14 ft
  Casper (shallow; without sensor):   39.70 ft   
  Casper (deep):                      39.61 ft

5/22/2018; 11:25 am MST; DTW from TOC; with Seth Davidson and Laura Hallburg from USGS:
  Granite:                            158.95 ft
  Casper (shallow; without sensor):   24.19 ft
  Casper (deep; with sensor):         24.49 ft