Ground Water Feasibility Study
ROBINSON & NOBLE, INCORPORATEO
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FEASIBILITY OF A MAJOR
GROUND WATER SUPPLY
WEST OF YELM
By John B. Noble
May, 1991
FEASIBILITY OF A MAJOR
GROUND WATER SUPPLY
WEST OF YELM
May, 1991
Introduction and Summary
I was requested by Dennis T. Su of Land Use & Devel-
opment Consultation, a division of Kramer, Chin & Mayo, to
contribute hydrogeological information to the enviromental
checklist concerning a proposed annexation to the City of
Yelm. The area considered for annexation is approximately
three square miles west of Yelm.
The study I performed consisted of a review and
assessment of existing well and geologic data and a field
reconnaissance around the proposed annexation area.
It is my opinion that major new water supplies can be
developed, but the area has limited valid information from
actual wells. On the Yelm prairie there is a shallow
aquifer with proven potential but subject to surface con-
tamination. Areas to the west have a likely potential for
ground water but exploration drilling is required for
verification.
Records of Wells
There are scores of individual well records within
two miles west and south of Yelm. The records are from
two sources. The older source is published in State Water
Supply Bulletin 10, Volume 1 (1961). The later source is
from the Dept. of Ecology well log files of Water Well
Reports filed by drillers. Of the records reviewed nearly
all reference 6-inch wells drilled for domestic use.
These wells are only minimally completed, developed and
tested. They generally serve the needs of their owners
but their data is not reliable to interpret if large water
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supplies could be present. The records show 19 wells
where major production has been proven or is probable.
None of these 19 is in the western annexation segment of
Section 26, 27, or 28.
The 19 wells with the most meaningful information are
listed on Table 1. Locations are on Figure 1. None was
field checked and, in the case of DOE records~ the loca-
tions are subject to reporting errors by the drillers.
The nomenclature of the Table 1 columns are as here noted.
Local i The section number in T17N/RIE (except
for the final well) followed by the letter
designator for the 1/16th section as used by
USGS. Thus, 24P is in Section 24, subsec-
tion uP" which is the SE 1/4 of SW 1/4.
Owner Name on the report
Dimensions Diameter of well in inches and depths
in feet.
Open interval Perforated or screened interval in
feet below top of well. A single depth
reported implies an open bottom well not
otherwise screened or perforated.
SWL Static water level, feet below top of well.
Q/s Discharge in gpm (Q) and drawdown in feet
( s ) .
Method Pumped or bailed to determine Q/s. (Bail-
ing is subject to major inaccuracy).
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PY Potential Yield. This is a theoretical yield
in gpm determined by factoring 2/3 of the
distance between SWL and top of the well's
open interval with the well's Q/s. As an
example, Well 24Ll was pumped at 360 gpm
with 5 feet drawdown (Q/s = 360/5 = 72).
The SWL is 14 feet and the top of the perfo-
rations are at 22 feet. Total drawdown dis-
tance is 22 - 14 = 8; 2/3 x 8 = 5.33. 72 x
5.33 = 384 gpm. The PY provides a degree of
comparison between wells but does not mean
that the particular well of record is actu-
ally capable of pumping that quantity.
Regime OWP = Outwash plain of the Yelm Prairie.
TMU = Till and morainal upland. See below
for further regime discussion.
Source DOE = State well record. Bulletin 10
State Water Supply Bulletin 10, Volume 1,
1961.
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TABLE 1 -- RECORDS OF SELECTED WELLS WEST OF YELM
LOCAL i OWNER DIMENSIONS OPEN INT. SWL Q/S METHOD PY REGIME SOURCE
(See text for column description)
T17N/R1E
24B1 LEWIS 12 x 99 85-93 34 165/6 PUMPED 935 OWP BULLETIN 10
24Ll SIMMONS 12 x 275 22-257 14 360/5 PUMPED 384 OWP BULLETIN 10
24P DRAGT 8 x 80 75-80 20 100/10 BAILED 367 OWP DOE
24Q NISQUALLY
GOLF COURSE 16 x 95 80-95 35 790/2.5 PUMPED 1000+ OWP DOE
25G BANKS 6 x 72 72 52 30/6 BAILED 67 OWP DOE
25H DOTSON 8 x 97 97 21 60/15 BAILED 203 TMU DOE
25J1 SIAS 72" x 8' 8 3 83/0.8 PUMPED 345 OWP BULLETIN 10
25K MERZ 6 x 163 163 72 40/20 BAILED 121 TMU DOE
25K PHILLIPS 6 x 75 75 58 15/1 BAILED 170 TMU DOE
25K FRAISSINET 6 x 83 83 55 20/5 BAILED 75 TMU DOE
34L CRAIG 6 x 196 196 180 20/6 BAILED 35 TMU DOE
34L2 HENSLEY 10 x 285 159-284 150 250/5 PUMPED 3,00+ TMU BULLETIN 10
34QorR MOES 8 x 181 181 135 60/20 BAILED 92 TMU DOE
35H HAMLING 6 x 59 59 34 45/2 BAILED 375 TMU DOE
35M CHERRY LN 2 8 x 100 100 58 60/5 BAILED 336 TMU DOE
35M CHERRY LN 1 6 x 100 100 72 20/1 BAILED 373 TMU DOE
35M McCOSHUM 6 x 140 140 110 20/1 BAILED 400 TMU DOE
36C SHAW 8 x 80 80 53 20/3 BAILED 120 TMU DOE
T17N/R2E
19N YELM #2 12 x 61 52-61 25 1250/5.2 PUMPED 1000+ OWP BULLETIN 10
fIGURE 1
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Ground Water Occurrence
There are two general geologic regimes with differing
ground water potential. These are here designated as (1)
outwash plain of the Yelm prairie (OWp) and (2) till and
morainal upland (TMU).
Wells of the OWP are typically shallow. They tap the
youngest, Vashon, glacial deposits. The Yelm City wells
and the Nisqually Golf Course well are examples of the
best. Some wells (as Simmons, 24Ll) have been drilled
deeper than the main aquifer but have been opened up to
the shallow zone, possibly because deeper zones were not
productive. Water levels are shallow and potential yield
can be very high. An abundant natural recharge contrib-
utes to the OWP from direct rainfall and from throughflow
from the west.
The aquifer has only minimal surface protection from
potential contamination. Gene Borges, Yelm's public works
director, informed me that nitrate content, an indicator
of surface contamination, has risen from 2.8 mg/l in win-
ter 1979 to 5.2 mg/l in winter, 1989. (The State limit
for nitrate is 10 mg/l.) The increase could result from
an increased population in the unsewered Yelm urban area.
Dairy cows also generate major amounts of nitrate that can
reach the ground water.
The till/morainal upland rises above the Ye1m prairie
on the south and west. The majority of the potential
annexation is in this regime. The morainal portion is
identified by the complex, hummocky topography typified ln
Section 27. This "kame-kettle complex results from gla-
cial deposition around stagnent ice with consequent slump-
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ing of the deposits as the ice melted. The residual
kettles are closed depressions that are generally dry,
implying that rainfall recharge readily permeates the
surface and does not run off as overland streams.
Wells that are drilled in the TMU show potential
yields up to 400 gpm. Depths are variable with the deep-
est of record (34L2) being 285 feet deep. Static water
level elevations are believed to be fairly consistent at
an elevation range of 350 to 400 feet. (Water level ele-
vation at Yelm is about 340 feet).
There appears to have been no planned or consistent
effort to complete major wells in the TMU. From the lim-
ited available data it appears that achieving 500 gpm or
more from single wells in that regime should be feasible.
Such a well would be carefully designed and developed to
maximize production from the most promising zones. Depths
to at least 400 feet should be considered.
Opinions & Conclusions
The Yelm area has a major ground water resource. The
major wells proven to date are limited to the shallow,
Vashon age outwash gravels of the Yelm Prairie. This
resource should not be discounted but it is vulnerable to
contamination. Elevated nitrate concentration documents
some degree of contamination.
The proposed annexation area is west of Yelm. Much
of that area has no meaningful well records. However, the
geology and topography is such that the area receives
virtually all local recharge and rejects very little as
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surface runoff. It is this area, particularly in Section
27, that a source of uncontaminated ground water is likely
to be found. At best, a successful source found in that
area would not only serve the new addition, it could sup-
plement or replace the original City supply.
Assuming that water levels are at elevation 375, any
exploration well should be targeted for a bottom depth at
elevation 75 to achieve considerable penetration of poten-
tial aquifers. Shallower completion would be done if a
major aquifer was encountered above target depth. A
single "dry" well should not cancel an exploration project
-- at least three wells should be considered across a
selected area. The morainal area is strewn with boulders
at surface. Boulders would be anticipated at depth. For
this reason exploration holes may best be done with air
rotary methods which can drill through boulders better
than other methods.
Respectfully submitted,
ROBINSON & NOBLE, INC.
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John B. Noble
Principal Hydrogeologist
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