Water Well Manual (USAID).pdf - The Water, Sanitation and Hygiene

More documents

Recommendations

Info

expansion and deepening of the cone of depression decreases with time. This is illustrated in Fig. 2.13 where C1 , C2 and C3 represent cones of depression at hourly intervals. The hourly increases in radius of influence, R, and drawdown, s, become smaller and smaller until the aquifer supplies a quantity of water equal to the pumping rate. The cone no longer expands or deepens and equilibrium is said to have been reached. This state may occur in any one or more of the following situations. Fig. 2.13 CHANGES IN RADIUS AND DEWTH OF CONE OF DE- PRESSION AFTER EQUAL INTERVALS OF TIME, AS- ~I$W&ONShUUT PUMP- . 1. The cone enlarges until it intercepts enough of the natural discharge from the aquifer to equal the pumping rate. 2. The cone intercepts a body of surface water from which water enters the aquifer at a ,rate equivalent to the pumping rate. 3. Recharge equal to the pumping rate is received from pre- cipitation and vertical infiltra- tion within the radius of influence. 4. Recharge equal to the pumping rate is obtained by leak- age through adjacent forma- tions. Where the recharge rate is the same from all directions around the well the cone remains symmetrical (Fig. 2.12). If, however, it occurs main!y from one direction, as may be the case with a surface stream, then the surface of the cone is higher in the direction from which the recharge takes place than in other directions (Fig. 2.14). Conversely, the surface of the cone is relatively depressed in the direction of an imperrnea&le boundary intercepted by it (Fig. 2.15). No recharge is obtained from such a boundary while that received from other directions maintains the higher levels in those directions. Recharge areas to aquifers, such as surface streams are, therefore, often referred to as positive boundaries while impermeable areas are known as negative boundaries. Mdtiple well system: Under some conditions the construction of a single large well may be either impractical or very costly while the installation of a group of small wells may be readily and economically accomplished. Factors such as the inaccessibility of the area to the heavy equipment required for drilling the large well and the high cost of transporting large diameter pipes to the site may be among the important considerations in a situation such as this. Small wells can be grouped in a proper pattern to give the equivalent performance of a much larger single well. The grouping of wells, however, presents problems due to interference among them when operating simultaneously. Interference between two or more wells occurs when their cones of depression overlap, thus reducing the 18
Discharging well Fig. 2.14 SYMMETRY OF CONE OF DEPRESSION AFFECJ.‘ED BY RECHARGE FROM STREAM. r Discharging well Fig. 2.15 CONE OF DEPRESSION IN VICINITY OF IMPERMEABLE BOUNDARY. 19
Page 1 and 2: A PRAGTICAL GUIDE FOR LOCATI CONSTR
Page 4 and 5: hmier Pwss Editorial Advisory Boani
Page 6 and 7: WATER EL1 MANUAL Covers Copyright @
Page 8 and 9: Page ACKNOWLEDGEMENTS ii FOREWORD 1
Page 10 and 11: S. PUMPING EQUIPMENT 114 CONSTANT D
Page 12 and 13: While man has always recognized ihe
Page 14 and 15: An understanding of the processes a
Page 16 and 17: Bsit of Soil Water tntermediate Bel
Page 18 and 19: and loess may be limited by both th
Page 20 and 21: deposition of large aprons of mater
Page 22 and 23: the pc>:ti,sity. This quautity is r
Page 24 and 25: permeability, P, we see from equati
Page 26 and 27: Flow Toward Wells Converging j&w: W
Page 30 and 31: yield of the individual wells (Fig
Page 32 and 33: Multiple well or well-point systems
Page 34: 10 ppm of iron means that in every
Page 37 and 38: ground waters in some parts of Arge
Page 39 and 40: Geologic Maps Geologic maps, of whi
Page 41 and 42: depth. thickness. and description o
Page 43 and 44: CHAPTER 4 Generally, the aim of eng
Page 45 and 46: lodged in them and thus restrict fl
Page 47 and 48: Fig. 4.3 THE Y-SHAPED OPENINGS OFTH
Page 49 and 50: Fig. 45 CONTBNUOUSSLOT T Y P E OF W
Page 51 and 52: Manufacturers make well screens in
Page 53 and 54: The limiting size of material to be
Page 55 and 56: too 90 E 60 z t 50 : .L 40 2 30 E (
Page 57 and 58: prime concern in small we!ls. Gener
Page 59 and 60: otherwise unsatisfactory water into
Page 61 and 62: The object of formation stabilizati
Page 63 and 64: Pump unit Sanitary well seal I / ,R
Page 65 and 66: There are four basic operations inv
Page 67 and 68: Ham? driver ----k- Htle backfilled
Page 69 and 70: single wlley block : /Tripod Fig. 5
Page 71 and 72: Fig,..8 MAN ON SCAFFOLDING RAISES H
Page 74 and 75: Cutting edges Galvanized iron pipe
Page 76 and 77: inexperienced driller because of th
Page 78 and 79:
string are usually joined together
Page 80 and 81:
.I Fig. 5.18 CAStbiG DRIVE SHOE. of
Page 82 and 83:
Fig. 5.22 A GRAVITY PLACEMENT METHO
Page 84 and 85:
Fig. 5.24 OUI’SIDE-TUBING METHOD
Page 86 and 87:
Pull-back Method The pull-back meth
Page 89 and 90:
Wash line- .Cemsnt grout ,’ Exoan
Page 91 and 92:
to the surface with the return flow
Page 93 and 94:
-Inner Carm~ Fig. 5.36 DOUBLE-CASIN
Page 95 and 96:
Lead packer Pulhg pipe Sand join1 S
Page 97 and 98:
saving that sbandunmcnt ot‘ the b
Page 99 and 100:
esult, tools lost in a hole do not
Page 101 and 102:
Tapered Tap Die Overshot Circulatin
Page 103:
If the hold is secure, continue lif
Page 106 and 107:
CHAPTER 6 WE11 C6MPLETION Well comp
Page 108 and 109:
‘N E L VI E L
Page 110 and 111:
Static water :evel -m----.-e Solid
Page 112 and 113:
The procedure is to lower the tool
Page 114 and 115:
wells. The thinner the gratlel pack
Page 116 and 117:
Wells, like all other engineering s
Page 118 and 119:
of the wells to determine whether s
Page 120 and 121:
Black iron or plastic pipe Well scr
Page 122 and 123:
,&ting technique is used to agitate
Page 124 and 125:
Drilling and completing a well form
Page 126 and 127:
container is termed the srrctiorl h
Page 128 and 129:
plunger on the tijrward stroke p~~s
Page 130 and 131:
or deep well type and are usually d
Page 132 and 133:
Fig. 8.9 VOLUTE-TYPE C’ENTRIFU- C
Page 134 and 135:
pre y.,,:~ 1; +-.b to, rourT the no
Page 136 and 137:
Check valve Radial bearing lmpetfer
Page 138 and 139:
To storage ha I 3 Power unit - Stat
Page 140 and 141:
Provision may also be made for pump
Page 142 and 143:
132
Page 144 and 145:
OF Too great stress can never be pl
Page 146 and 147:
feet before final disappearance at
Page 148 and 149:
REFERENCES Acme Fishing Tool Compan
Page 150 and 151:
T OF PE ICITY The coefficient of pe
Page 152 and 153:
Unit TABLE B.3 VOLUME Equivalents o
Page 154 and 155:
- B-8 PRESSURE 1 Atmosphere = 760 m
Page 156 and 157:
TABLE B-14 ESTIMATING DISCHARGE FRO
Page 158 and 159:
-z- TABLE B.16 DRILLING CABLE ROPE
Page 160 and 161:
A Abandoned well, I37 Acid. hydroch
Page 162 and 163:
Gelling, 64 Geologic cross-sections
Page 164 and 165:
s Sand, 7,9? 119, 126, 129, 137 --
show all

Water Well Manual (USAID).pdf - The Water, Sanitation and Hygiene

Create successful ePaper yourself

Delete template?

Save as template?