Seabee Mission: Senegal Water Well

Seabee Mission: Senegal Water Well

By Scott Bryant

On a water well installation mission to Senegal, Africa a Navy Seabees Team needed to test the potability/usability of the local groundwater at the drilling site. Until now the local tribe has been carrying water buckets for long distances each day, by hand, from a local stream. This well will give the villagers a clean water source of potable water, installed very close to the town square. The first step is to take a measure of the dissolved particulate concentration in the groundwater. Dissolved particulate concentration levels are measured in milligrams per Liter (mg/L). The water will be put in slides, studied under a microscope, poured through a microfiber sieves, and the weight per liter will be taken.

To assure that the water is safe to consume the team will need to send the samples to a certified laboratory for testing. Harmful bacteria, parasites, and viruses are invisible to the naked eye, so water that looks and tastes good may not necessarily be safe to drink. These microbes can exist in surface and groundwater supplies, and can cause immediate sickness in humans if not properly treated. It is important to test the drinking water at the tap and at the source. Testing both locations will alleviate the chance that the quality of the water changes through the extraction process. From first onsite assessment the water appears to have some potability issues. There are visible specs in the water and there are is a slightly foggy tent to the samples. The first set of test results (source/tap) are as followed:

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7.6, 3.1, 3.6, 6.2, 8.8, 4.2

Sample Average:

7.6+3.1+3.6+6.2+8.8+4.2= 33.5

33.5/6= 5.583 or 5.6 mg/L

Variance:

7.6-5.6= 2/ (2)^2= 4

3.1-5.6= -2.5/ (-2.5)^2= 6.25

3.6-5.6= -2.0/ (-2.0)^2= 4

6.2-5.6= -.6/ (.6)^2= .36

8.8-5.6= 3.2/ (3.2)^2= 10.24

4.2-5.6= -1.4/ (-1.4)^2= 1.96

4+6.25+4+.36+10.24+1.96= 26.81

26.81/5= 5.362...