# **Problem 5.1** # A community is installing a new well in a regionally confined aquifer # with a transmissivity of 1589 ft2/day and a storativity of 0.0005. The # planned pumping rate is 325 gal/min. There are several nearby wells # tapping the same aquifer, and the project manager needs to know if the # new well will cause significant interference with these wells. Compute # the theoretical drawdown caused by the new well after 30 days To = 1589 ft^2/day So = 0.0005 Q = 325 gal/min t = 30 day r1 = 50 ft r2 = 150 ft r3 = 250 ft r4 = 500 ft r5 = 1000 ft r6 = 3000 ft r7 = 6000 ft r8 = 10000 ft u1 = r1^2 * So / (4 * To * t) u2 = r2^2 * So / (4 * To * t) u3 = r3^2 * So / (4 * To * t) u4 = r4^2 * So / (4 * To * t) u5 = r5^2 * So / (4 * To * t) u6 = r6^2 * So / (4 * To * t) u7 = r7^2 * So / (4 * To * t) u8 = r8^2 * So / (4 * To * t) Wu1 = ExpInt(u1) # The function W(u) = ExpInt(u) Wu2 = ExpInt(u2) Wu3 = ExpInt(u3) Wu4 = ExpInt(u4) Wu5 = ExpInt(u5) Wu6 = ExpInt(u6) Wu7 = ExpInt(u7) Wu8 = ExpInt(u8) s1 = Q * Wu1 / (4 * pi() * To); ft s2 = Q * Wu2 / (4 * pi() * To); ft s3 = Q * Wu3 / (4 * pi() * To); ft s4 = Q * Wu4 / (4 * pi() * To); ft s5 = Q * Wu5 / (4 * pi() * To); ft s6 = Q * Wu6 / (4 * pi() * To); ft s7 = Q * Wu7 / (4 * pi() * To); ft s8 = Q * Wu8 / (4 * pi() * To); ft # **Problem 5.3** # Plot the distance-drawdown data from Problem 1 on semilog paper. # See answer on page 564 of text. # **Problem 5.5** # Plot the distance-drawdown data from Problem 2 on semilog paper # See answer on page 565 of text. # **Problem 5.7** # If the aquifer in Problem 1 is not fully confined, but is overlain by a # 13.7-ft-thick confining layer with a vertical hydraulic conductivity of # 0.13 ft/day and no storativity, what would be the drawdown values after # 30 days of pumping at 325 gal/min at the indicated distances? To = 1589 ft^2/day So = 0.0005 Q = 325 gal/min t = 30 day b_prime = 13.7 ft K_prime = 0.13 ft/day r1 = 50 ft r2 = 150 ft r3 = 250 ft r4 = 500 ft r5 = 1000 ft r6 = 3000 ft r7 = 6000 ft r8 = 10000 ft u1 = r1^2 * So / (4 * To * t) u2 = r2^2 * So / (4 * To * t) u3 = r3^2 * So / (4 * To * t) u4 = r4^2 * So / (4 * To * t) u5 = r5^2 * So / (4 * To * t) u6 = r6^2 * So / (4 * To * t) u7 = r7^2 * So / (4 * To * t) u8 = r8^2 * So / (4 * To * t) B = sqrt(To*b_prime/K_prime) c1 = r1/B c2 = r2/B c3 = r3/B c4 = r4/B c5 = r5/B c6 = r6/B c7 = r7/B c8 = r8/B Wu_rB1 = 4.56 # from Appendix 3 Wu_rB2 = 2.44 Wu_rB3 = 1.53 Wu_rB4 = 0.71 Wu_rB5 = 0.18 Wu_rB6 = 0.001 Wu_rB7 = 0 Wu_rB8 = 0 s1 = Q * Wu_rB1 / (4 * pi() * To); ft s2 = Q * Wu_rB2 / (4 * pi() * To); ft s3 = Q * Wu_rB3 / (4 * pi() * To); ft s4 = Q * Wu_rB4 / (4 * pi() * To); ft s5 = Q * Wu_rB5 / (4 * pi() * To); ft s6 = Q * Wu_rB6 / (4 * pi() * To); ft s7 = Q * Wu_rB7 / (4 * pi() * To); ft s8 = Q * Wu_rB8 / (4 * pi() * To); ft # **Problem 5.9** # With reference to the well and aquifer system in Problem 1, compute the # drawdown at a distance of 250 ft at the following times: 1, 2, 5, 10 # 15, 30, and 60 min; 2, 5, and 12 h; and 1, 5, 10, 20, and 30 days. To = 1589 ft^2/day So = 0.0005 Q = 325 gal/min r = 250 ft t1 = 1 min t2 = 2 min t3 = 5 min t4 = 10 min t5 = 15 min t6 = 30 min t7 = 60 min t8 = 2 hr t9 = 5 hr t10 = 12 hr t11 = 1 day t12 = 5 days t13 = 10 days t14 = 20 days t15 = 30 days u1 = r^2 * So / (4 * To * t1) u2 = r^2 * So / (4 * To * t2) u3 = r^2 * So / (4 * To * t3) u4 = r^2 * So / (4 * To * t4) u5 = r^2 * So / (4 * To * t5) u6 = r^2 * So / (4 * To * t6) u7 = r^2 * So / (4 * To * t7) u8 = r^2 * So / (4 * To * t8) u9 = r^2 * So / (4 * To * t9) u10 = r^2 * So / (4 * To * t10) u11 = r^2 * So / (4 * To * t11) u12 = r^2 * So / (4 * To * t12) u13 = r^2 * So / (4 * To * t13) u14 = r^2 * So / (4 * To * t14) u15 = r^2 * So / (4 * To * t15) Wu1 = ExpInt(u1) # The function W(u) = ExpInt(u) Wu2 = ExpInt(u2) Wu3 = ExpInt(u3) Wu4 = ExpInt(u4) Wu5 = ExpInt(u5) Wu6 = ExpInt(u6) Wu7 = ExpInt(u7) Wu8 = ExpInt(u8) Wu9 = ExpInt(u9) Wu10 = ExpInt(u10) Wu11 = ExpInt(u11) Wu12 = ExpInt(u12) Wu13 = ExpInt(u13) Wu14 = ExpInt(u14) Wu15 = ExpInt(u15) s1 = Q * Wu1 / (4 * pi() * To); ft s2 = Q * Wu2 / (4 * pi() * To); ft s3 = Q * Wu3 / (4 * pi() * To); ft s4 = Q * Wu4 / (4 * pi() * To); ft s5 = Q * Wu5 / (4 * pi() * To); ft s6 = Q * Wu6 / (4 * pi() * To); ft s7 = Q * Wu7 / (4 * pi() * To); ft s8 = Q * Wu8 / (4 * pi() * To); ft s9 = Q * Wu9 / (4 * pi() * To); ft s10 = Q * Wu10 / (4 * pi() * To); ft s11 = Q * Wu11 / (4 * pi() * To); ft s12 = Q * Wu12 / (4 * pi() * To); ft s13 = Q * Wu13 / (4 * pi() * To); ft s14 = Q * Wu14 / (4 * pi() * To); ft s15 = Q * Wu15 / (4 * pi() * To); ft # **Problem 5.11** # Plot the time-drawdown data from Problem 9 on semilog paper. # See answer on page 566 of text. # **Problem 5.13** # A well that pumps at a constant rate of 78,000 ft3/day has achieved # equilibrium so that there is no change in the drawdown with time. (The # cone of depression has expanded to include a recharge zone equal to the # amount of water being pumped.) The well taps a confined aquifer that is # 18 ft thick. An observation well 125 ft away has a head of 277 ft above # sea level; another observation well 385 ft away has a head of 291 ft. # Compute the value of aquifer transmissivity using the Thiem equation. Q = 78000 ft^3/day b = 18 ft h1 = 277 ft r1 = 125 ft h2 = 291 ft r2 = 385 ft To = (Q/(2*pi()*(h2-h1)))*ln(r2/r1); ft^2/day