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Newoffice/Projects/2018/1811-LantzvilleClarkRoad/MEMO-WellTestingFourWells/Oct2018
LOWEN HYDROGEOLOGY CONSULTING LTD.
PO Box 45024 Victoria, B.C. Canada V9A 0C3
Phone: 250-595-0624 - Fax: 1– 855-286-8001 Website: www.lowenhc.ca - e-Mail: dl@lowenhc.ca
MEMORANDUM
TO: Darwin Mahlum – Sincana Land Corp. E-MAIL: darwin@darwingroup.ca
FROM: Dennis Lowen DATE: October 17, 2018
RE: Well Testing at Four Wells Nos. 54918, 36808, 36879 and 36876 PROJECT: 1811, 1812 & 1817
# OF PAGES 47
Message:
As requested, we have supervised well testing on four wells owned by Sincana Land Corporation as follows:
Well ID #
Location Property
54918 (Well #11) Near Harby Road Well Field Downtown
36808 Clark Road Clark
36879 Clark Road Clark
36876 Dover Road Ryeland
The four wells drilled between 1988 and 2013 were pumped to obtain an updated water quality sample and wells
#54918 and #36808 were re-tested to confirm their capacity. These two wells were tested previously in springtime
however, testing in the fall is considered more accurate. See Figure 1 for the well locations in the District of
Lantzville.
Well #54918 (Well #11)
A 24-hour constant rate pumping test was carried out on Well 54918 on September 17 and 18, 2018. The Well
was pumped at a constant rate of 7.89 L/s (125 USgpm) with initial and final water levels of 6.77 and 17.27 m.
below top casing, respectively. Water levels at three Lantzville Wells, #4, 6A and 12, were monitored during the
pumping period. Wells #4 and 6A were off but Well #12 was on for portions of the test period. Figure 2 presents
the drawdown graph and Appendix A provides the water level data.
The capacity of Well 54918 has been determined as follows, using the Ministry of Environment (1999)
methodology:
Formula: Yield = 0.7 x Specific capacity(100 days) x Total available drawdown
Where: - Specific capacity = Pumping rate/Extrapolated Drawdown @100 days = 0.730 L/s/m
- Total Available Drawdown = Top of the screen level - Static Water Level = 15.4 m.
- Safety Factor = 30%
Therefore: Yield = 0.7 x 0.730 L/s/m x 15.4 m.
Yield = 7.86 L/s (124.6 USgpm)
Memo: October 17, 2018 Re: Well Testing at Four Wells Nos. 54918,36808,36879 and 36876
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Figure 1
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Well 54918 (Well #11) will be pumped simultaneously with nearby Lantzville’s Harby Road Wells # 4, 5, 6A and
12. The mutual water level drawdown impacts between these wells must be considered to determine the net
benefit of this well when added to Lantzville’s Water System.
Pumping the Lantzville wells will draw down the well 54918 water level and subsequently reduce its capacity.
Previous pumping tests at Lantzville’s wells (2016 – 2017) indicated a 0.95 m. drawdown at Well 54918 after 100
days pumping Wells 4, 5, 6A and 12. Therefore, the Well 54918 capacity would be reduced by; 0.95 x 0.730 =
0.69 L/s.
The pumping impact of Well 54918 has been estimated from the 2017 test on Well 54918 at 6.31 L/s.
Drawdown at Well #
100 days @ 6.31 L/s 100 days @ 7.86 L/s Specific Capacity Lantzville Wells
Capacity Impact L/s
4 0.16 0.200 0.980 0.196
5 0.380 0.475 0.354 0.168
6A 0.380 0.475 0.800 0.380
12 0.225 0.281 1.024 0.288
Total 1.032 L/s
See Figure 2 for a drawdown graph from the 2018 pumping test and Figure 3 for the 2017 testing with impact on
Lantzville Wells.
Figure 2
Memo: October 17, 2018 Re: Well Testing at Four Wells Nos. 54918,36808,36879 and 36876
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Figure 3
Considering mutual water level drawdown impacts Well 54918 will provide the Lantzville Water System a net
benefit as follows:
Well 54918 Capacity = 7.86 L/s
Capacity reduction due to Lantzville Wells = 0.69 L/s
Capacity reduction at Lantzville Wells = 1.03 L/s
Final Capacity = 6.14 L/s
Credit for Well 54918 = (97.3 USgpm)
Therefore, the production capacity of the District of Lantzville Water System will be increased by 6.14 L/s (530
m3/d) with the addition of Well 54918 (LID #11)
Well #36808
A 48-hours constant rate pumping test was carried out on Well 36808 on Sept 18, 19 and 20, 2018. This well had
been tested previously in April of 2012 and a confirmation test was recommended to be conducted in the fall when
groundwater levels are lowest. The well was pumped at a constant rate of 3.79 L/s (60 USgpm) with initial and
final water levels of 16.47 m and 27.56 m. below top of casing respectively. Water levels at two observation wells
36801 and 36879 were recorded during pumping. Figure 4 presents a graph of the observed water level data. All
the water level data is presented in Appendix A.
The pumping test data has been used to determine well capacity as follows:
Formula: Yield = 0.7 x Specific capacity(100 days) x Total available drawdown
Therefore Yield = 0.7 x 0.314 L/s/m x 18.4 m.
Yield = 4.05 L/s (64 USgpm)
y = 0.0187ln(x) - 0.064R² = 0.8813
y = 0.0303ln(x) + 0.0157R² = 0.9072
y = 0.0207ln(x) - 0.0197R² = 0.8302
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00
Dra
wd
ow
n (
m)
Elapsed time (min)
Well # 11 Pumping - Harby Rd Wells ResponseTime vs. Drawdown (April 2017)
Well 4 Well 6 Well 12 Log. (Well 6) Log. (Well 12) Log. (Well 12) Log. (Well 12)
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Figure 4
Well 36808 is located 95 m. west of Well 36879 and both are proposed for inclusion in the District of Lantzville
Water System. As the wells will be pumped simultaneously then mutual water level drawdown impacts must be
considered. In the original well report “Production Well Construction, Clark Drive, Lantzville, BC”, GW Solutions
(GWS), July 31, 2013 the interference at well 36808 from Well 36879 was calculated at 0.60 m. and our testing in
2018 supports this conclusion. Therefore, the final or corrected yield for Well 36808 is calculated as:
Pump test Yield = 4.05 L/s
Reduction due to drawdown interference = 0.6 x 0.314 = 0.8188 L/s
Final Yield = 3.86 L/s (61.2 USgpm)
Therefore, well 36808 can be included in the Lantzville Water System and provide an additional 3.86 L/s of
capacity.
Well #36879
Well 36879 was previously pump tested on August 27, 2012 and the analysis of this testing is provided in the GWS
(July 2013) Well Report. We agree with the testing results presented in this report and consider the yield
calculation to be valid, considering the late summer timing. In our opinion the yield calculation by GWS is slightly
under-estimated because they included a 1.5 m. reduction in available drawdown due to seasonal water level
variation. For a late August test this allowance should be 0.5 m. This leads to a yield calculation as follows:
Yield = 0.7 x available drawdown x specific capacity
Yield = 0.7 x 13.5 x 0.347
Final Yield = 3.28 L/s (52 USgpm)
The GWS Report concluded the safe yield to be 3.03 L/s.
We concluded a short (4-hour) pumping test on well 36879 on September 21, 2018 primarily to obtain an updated
water quality sample and water level drawdown was observed. All water level monitoring data is attached as
Appendix A.
y = 0.1114ln(x) + 10.721R² = 0.8268
0.00
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4.00
6.00
8.00
10.00
12.00
14.00
0.1 1 10 100 1000 10000 100000
Pump Test Drawdown - Well 36808
WELL 36808 WELL 36801 WELL 36879 Series4 Log. (Series4)
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Well efficiency was compared for the 2012 and the 2018 pumping test as follows:
Test Date
Flow L/s
Drawdown @ 100 min
Drawdown @ 200 min
Specific Capacity @ 100 min.
Specific Capacity @ 200 min.
2012 3.72 10.142 10.175 0.367 0.365
2018 3.78 7.95 7.98 0.475 0.474
The specific capacity (discharge rate/drawdown) determined from pumping is directly related to well efficiency.
Our well efficiency calculations from the 2018 testing indicate a significantly higher efficiency than the 2012 testing.
The well efficiency improvement is approximately 30%. This indicates that the well may be able to produce more
than the 2012 pumping test analysis indicates. This would require a full scale, minimum 24-hour pumping test to
confirm. In any case the efficiency comparison indicates the well rating from 2012 is conservative.
Well #36876
Well 36876 was tested in 2012 by way of a constant rate test from July 9 to July 12 for a 72 hours duration. The
initial and end water levels were; 32.4 and 73.2 m., respectively, in response to the pumping at 6.9 L/s (110
USgpm.
The 2012 pumping test is included in the GWS Report “Source of Drinking Water Supply – Production Well, Dover
Road, Lantzville, B.C.” July 31, 2013. On page 23, Table 5, in the report the Safe Yield is calculated. The specific
capacity is reported as 0.170 L/s/m however, the data indicates this should be 0.134 L/s/m in which case the yield
would be reduced to 4.12 L/s compared to the 5.23 indicated in the report. This discrepancy is significant, and we
propose to discuss the issue with GWS.
Additionally, following our pumping and sampling the well, we compared water level drawdown data to access well
efficiency. Results are as follows:
Test Date
Flow L/s Drawdown @ 100 min
Drawdown @ 200 min
Specific Capacity @ 100 min.
Specific Capacity @ 200 min.
2012 6.90 21.208 25.084 0.325 0.275
2018 5.05 16.620 19.201 0.304 0.263
The well efficiency has decreased slightly by 4.4% between 2012 and 2018. With longer term pumping the well
efficiency may increase. With the well not being used for 6 years it is common for efficiency to decrease. Over
time the well screen and surrounding formation can become siltier, decreasing the efficiency of the flow into the
well screen.
Water Quality Analyses
The four subject wells were sampled for water chemistry and bacterial analysis during their respective pumping
periods. The wells were also chlorinated prior to pumping to negate any potential for bacteria contamination from
the pumping operation. All sample collection followed proper sampling protocol and the samples were delivered
to the Lab in acceptable time frames.
The following water quality issues were identified:
Well # Property Exceedances
Bacteria (Maximum) Iron (Aesthetic Objective)
54918 (LID #11) Downtown
36808 Clark
36879 Clark
36876 Ryeland
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The Iron exceedance at Well 36879 is only minor and iron will likely decrease with prolonged pumping. All the
wells sampled had total coliforms above acceptable values and Well 36879 had high values for total coliforms and
e-coli. This well has a 3 m. long sump below the screen and this may be where the bacteria occur and are difficult
to remove. The bacteria exceedances are not related to the aquifer but are water well specific. The wells must
be chlorinated (including sumps below the screens) and re-sampled prior to making a Water Source Approval
submission to MOH. We will make a recommendation to address this issue. Water testing results are presented
in Appendix B.
SUMMARY
A review of GWS Reports and four pumping tests has confirmed the following well capacities:
Well # Property Capacity L/s
Individual Combined
54918 (LID #11) Downtown 7.86 6.14
36808 Clark 4.05 3.87
36879 Clark 3.54 3.28
36876 Ryeland 4.12 4.12*
* May be revised after consultation with GWS.
The wells can be pumped at the Individual Rate when nearby wells are off, but when nearby wells are on the
combined rated capacity applies.
The water production capacity increases due to the four subject wells will allow the District of Lantzville to service
additional customers (water connections). We understand each water connection requires a flow of 3,400 L/d.
Therefore, the subject wells can provide for additional connections as follows:
Well # Capacity
L/s L/d No. of Connections
54918 (LID #11) 6.14 530,496 156
36808 3.87 334,368 98
36879 3.28 283,392 83
36876 4.12 355,968 104
Total Connections: 441
If you have any questions or require any further information, please contact the undersigned.
Best regards,
Dennis A. Lowen, P. Eng., P. Geo. DL/hr
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