U.S. ARMY ENGINEER DIVISION, PACIFIC OCEAN CORPS PROJECT TITLE >, Jn ET _ rae OF ENGINEERS “4a. . wf OrousitviiG Vr te. SH NO. LOCATION DRAWING (S) NO. Noone: Wales COMPUTED ay___'¥__! tH’ well be brant ist, ; _ _f OF SECTION Pervta fa, DSN, pate! Ort CHECKED BY _33 SHS an 4 noatrny DATE DESIGN ANALYSIS SKIMMING WELL AT RUNIT The estimate of recharge piven on pape 50, ref b, hepinning on line 8 of It fails to follow even third paragraph is significantly overoptimistic. Lipht rains falling on report. same the the puidelines given on page 10 of uptake and soil mois, plant evaporation to dry soil may be completely lost ture uptake." In addition rain falling within 100 feet of the shoreline It is noted generally contributes little or no fresh water to the lens. A more shore. lagoon the that the 100m radius centered at Y~-3 intersects conservative estimate of recharge estimate is as follows: Consider the maximum circle whose perimeter does not extend closer than 100 feet to the shoreline: ie, a 500 ft diameter circle whose center is about 350 feet from either shore, and about 22 north of centerline of air strip: 500" diam circle = 196,350 et? area annual recharge = 25% x 57.88 inches + 12 x 196,350 = 236,764 cp ft x 7.48 1.77 x 10 gal/yr + 365 4,850 pal/dav Required Capacity = 3,900 gal/day The ground water level at center may he expected to be only about 0,2 feet above lapoon level at mean tide, The tidal efficiency may he expected to be about 9.10, that is the tidal range of the ground water may be expected to be about 0.4 feet. The well will consist of a 12" diam corrupated metal pipe ahout 12 feet long, securely sealed at the bottom with a 1/4" plate welded watertipht. The collector pipes will be 5-60 feet long, 2 inch diam corrugated polyethylene drainace tuhing. This tubing is Commercial Standard CS 228-61 is available from several sources including Hancor Inc., PO Box 1047, Findlay, Ohio 45840, and Advanced Drainape System, Inc., TO Box 489, Pomona, CA 91769. The 2-inch collector tubes will radiate equally spaced at about 72°. The collector tubes must be precisely placed at the level of 1.0 ft belov the mean fround water elevation. The latter criterion is extremely important hecause of the very thin brackish waterlines. The pump will he 1/2 hp 230 volt single-phase submersible pump rated at 10 ppm. This pump is available from Sears and other sources. It is verv important to avoid using an oversized pump, in order to prevent excessive drawdown. A windmill] can be substituted: 27' tower, 8' diam fan, 2-3/4" x 12" x 24" pump cylinder rated at 6,000 ppd @ 15‘ lift: Aeromotor or equal. POD Form 115 1 Jul 70 Oe Eeei Paneee9 RP iewee mon Th dee Eke ee EP. ef ye A ight echt hal: Fug PUNE Oy oe a seh eg PENS EETAIE Beied SieNaate cg mihev a. pee crATE eG * haga