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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: [email protected]

MEMORANDUM

TO: Darwin Mahlum – Sincana Land Corp. E-MAIL: [email protected]

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)

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Memo: October 17, 2018 Re: Well Testing at Four Wells Nos. 54918,36808,36879 and 36876

Page 2 of 47

Figure 1


Page 3 of 47

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


Page 4 of 47

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)


Page 5 of 47

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

2.00

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)


Page 6 of 47

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.


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



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


Page 7 of 47

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

Memo: October 17, 2018

Re: Well Testing at Four Wells Nos. 54918,36808,36879 and 36876

Appendix A - Page 8 of 47















Appendix B - Page 13 of 47







































































































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