Question

An underground aquifer near Seiling, Oklahoma, sits on an impermeable layer of limestone. West of Seiling the limestone layer is thought to slope downward in a straight line. In order to map the limestone layer, hydrologists started at Seiling heading west and drilled sample wells. Two miles west of Seiling the limestone layer was found at a depth of 220 feet. Three miles west of Seiling the limestone layer was found at a depth of 270 feet

(a) What would you expect to be the depth of the limestone layer 5 miles west of Seiling
(b) You want to drill a well down to the limestone layer as far west from Seiling as you can. Your budget will allow you to drill a well that is 275 feet deep. How far west of Seiling can you go to drill the well? (Round your answer to one decimal place.)

Answer 1

(A) 490ft.

(B) 2.8 miles

Explanation:

Important points to note:

- The limestone layer is thought or assumed to slope downward in a straight line.

- 2 miles west of Seiling, the limestone layer was found at a depth of 220ft.

- 3 miles west of Seiling, the limestone layer was found at a depth of 270ft.

(A) What would you expect to be the depth of the limestone layer, 5 miles west of Seiling?

The expected depth of the limestone layer is:

2 miles + 3 miles = 5 miles

220ft + 270ft = 490ft

(B) Your budget will allow you drill a well that is 275ft deep. How far west of Seiling (in miles) can you go, to drill the well?

If 490ft ~ 5 miles

then 275ft ~ K miles

K = [275 x 5] / 490 = 2.80612245 miles

Rounding to 1 decimal place, the distance is 2.8 miles.