Water Supply Wells

NOTE This standard governs the construction of a drilled water supply well, from the well construction permit and the mobilization of the drilling rig through the casing, the annular seal, the screen, the filter pack, the development, the plumbness and alignment survey, the test pumping, the water quality sampling, the disinfection, and the wellhead completion, and it ends at the well record that states what was built and what the well produces. (1.1)

NOTE The standard is written for a well that is a public water supply source or the raw, process, or service water supply of a treatment plant or an industrial facility; it applies to a private domestic or irrigation well where the drawings assign it, because the state well construction code holds a private well to the same casing, seal, and setback rules and differs only in the approvals that follow. (1.2)

NOTE This standard is read with Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process, which carries the submittal register, the factory and witnessed test policy, the manufacturer's field services, the nameplate basis, the spare parts policy, the anchorage basis, and the vibration and noise limits for the equipment on the project; those obligations apply to the well and are not restated here. (1.3)

NOTE This standard ends where Vertical Turbine PumpsVertical Turbine PumpsResolves to the current adopted revision.sync/vertical-turbine-pumps begins. The permanent pump, whether a deep-well line-shaft turbine or a submersible well pump, with its motor, column, discharge head, cable, column check valve, and the pitless unit or discharge tee where the pump manufacturer furnishes it, and the pump field test, are that standard's. The temporary test pump used for the test pumping is within this standard, because it is removed when the test is complete and is never the pump the well is operated with. (1.4)

NOTE The well record this standard delivers, with the casing inside diameter, the total depth, the screen settings, the static and pumping water levels, the specific capacity, the sand content, the recommended production rate, and the plumbness and alignment result, is the document the pump standard reads when it selects the bowl assembly against the casing, sets the pump against the pumping water level, and chooses the bearing materials against the sand content. The well is drilled, tested, and recorded before the pump is ordered, and a pump ordered against a planned well rather than a recorded one is the defect this sequence exists to prevent. (1.5)

NOTE The depth, the diameter, the target aquifer, the anticipated yield, and the test pumping rate are the hydrogeologist's design and live on the well plan and section and in the well design memorandum; this standard carries no norm for any of them. The screen slot and the filter pack gradation are designed from the formation samples after the pilot hole is drilled, and that design is a hold point before the screen is ordered rather than a value this standard asserts. (1.6)

NOTE The following are outside this standard: (1.7)

NOTE The state well construction code is the governing document for the sealed depth, the annular width, the grout materials the state admits, the casing stickup, the sanitary setbacks, the driller's license, the well completion report, and the abandonment procedure; AWWA A100 is the construction standard the industry writes against, and where the two differ the code governs because it is the one with a permit behind it. (2.3)

NOTE Most states license well drillers separately from excavation, utility, and plumbing contractors, and most license the pump installer separately again; the state inspects the license before it accepts the well completion report, and a well drilled by an unlicensed crew is a well the state does not accept as a public water supply source whatever its construction. (4.1.4)

NOTE The hydrogeologist's role is the one the geotechnical engineer plays on an earthwork site: the well design memorandum was written from regional data and a test hole or two, and the aquifer the bit actually reaches is confirmed or contradicted foot by foot as the samples come up, so the person who wrote the memorandum is the one positioned to revise it. (4.2.5)

NOTE A public water supply source brings the primacy agency into the design, the siting, the sampling, and the approval to operate, and brings the drinking water contact certifications with it; a plant service or process well and an industrial supply well are permitted by the state well program under the same construction rules and sampled for the parameters the use needs rather than the full new-source list; an irrigation well is held to the construction code and to the water right and little else; a private domestic well is permitted and inspected by the state or county well program and released on a bacteriological sample. The use changes who approves the well and what is sampled, not how it is built. (4.3.5)

NOTE The setback runs both ways: the well constrains where Permeable PavingPermeable PavingResolves to the current adopted revision.sync/permeable-paving, Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems, Sanitary Sewer SystemsSanitary Sewer Systems (Site)Resolves to the current adopted revision.sync/sanitary-sewer-systems, and Fuel Dispensing And Storage TanksFuel Storage TanksResolves to the current adopted revision.sync/fuel-dispensing-and-storage-tanks place their facilities, and those standards carry the setback from the well as a requirement on their work; the well plan is the drawing on which the Engineer of Record reconciles the two. (4.4.3)

NOTE A well is built in a hole no one can see into, and each hold point is the last moment at which a decision is still reversible: a screen set in the wrong interval, a seal placed over a cavity, and a filter pack that bridged halfway down are each found afterward only by pulling the well apart or abandoning it. (4.6.3)

NOTE The depth, the diameter, and the yield are the hydrogeologist's reading of the aquifer and the pump the Owner intends to set in it, and no well standard has a norm for any of them; they defer to the memorandum because that is where the hydrogeologist recorded them, and the as-built well record is where the values the well actually delivered are written beside them. The casing diameter is also the first number the pump standard reads, because the bowl assembly and the submersible motor are chosen to fit inside it with the clearance the pump manufacturer requires. (5.1.5)

NOTE The drilling fluid, the dispersant, and the chlorine are the chemicals that go down the hole on every well, and NSF/ANSI/CAN 60 certification is what lets the primacy agency accept that they left nothing behind; the casing and screen certification under NSF/ANSI/CAN 61 is required by some states and not by others, which is why the first clause reads from the code and the second does not. (5.2.3)

NOTE Cable tool drills by lifting and dropping a bit, drives the casing as it goes, uses no drilling fluid, and produces the cleanest formation samples and the most reliable water level observations of any method, at a rate of a few tens of feet per day; it is the method for a boulder or cobble formation, for a shallow unconsolidated aquifer where fluid loss or formation damage is the concern, and for a site where the rig the Contractor has is a cable tool rig. Direct mud rotary circulates a bentonite fluid down the drill pipe and up the annulus, holds the hole open with the fluid column, and drills unconsolidated and soft rock formations in days rather than weeks, at the cost of a filter cake on the aquifer face that development has to remove and samples that arrive mixed and delayed by the circulation time. Reverse-circulation rotary pulls the fluid up the drill pipe at a velocity that lifts coarse cuttings, runs on water with little or no additive, and drills the large-diameter hole in unconsolidated sand and gravel that a municipal filter-packed well needs, at the cost of a large water supply, a large pit, and a formation that stands open only where the water table is deep enough to hold a fluid head. Air rotary lifts the cuttings with compressed air, drills consolidated rock faster than any fluid method, shows the water as it is encountered, and leaves no cake, and it cannot hold an unconsolidated formation open. Air rotary with a casing hammer, and dual rotary which turns the casing and the drill string independently, advance the casing with the bit through overburden, boulders, and caving sand, so the hole is cased as it is drilled, at the cost of a rig that is not everywhere available. (6.1.2)

NOTE Above-ground tanks keep the fluid, the cuttings, and the additives off the ground and out of the water table and are what a public water supply site and a tight site call for, at the cost of tank rental and a pump to move the fluid; a lined pit holds a larger volume for a reverse-circulation rig and depends on a liner that survives the excavator; an unlined pit is the cheapest containment, is admitted by some codes on a rural site in tight soil, and puts the fluid into the ground within feet of the well that is supposed to be protected from it. (6.1.6)

NOTE A pilot hole is drilled small and fast to the design depth, logged, and sampled, so the screen interval and the filter pack are designed against the formation that is actually there before the full-diameter hole is cut; the single pass saves the reaming on a cable tool well, on a hammer-cased well that cannot be reamed, and on a small well where the formation is known from a test hole beside it. (6.2.2)

NOTE The sieve curve of the aquifer sand is the single input from which the slot size, the filter pack gradation, and the pack-to-formation ratio are designed, and a well with a sand problem for its whole life is usually a well whose samples were taken too far apart, mixed across a formation change, or sieved after the screen was ordered. (6.3.6)

NOTE Resistivity and spontaneous potential together distinguish the permeable sand from the clay in an unconsolidated section and show where the formation water changes quality, natural gamma reads the clay content through casing and in a hole that has no fluid, and the caliper measures the hole diameter the annular grout and filter pack volumes are calculated from; those four are the suite a rotary pilot hole in an unconsolidated aquifer is logged with, and a cable tool well that was sampled every few feet and had its water level measured as it went is sometimes logged with gamma and caliper alone. The fluid log locates the zones that contribute flow and the interface between fresh and brackish water, and the spinner log measures how much of the yield each zone delivers, which matters where the screen is to be set in some zones and blanked across others. (6.4.2)

NOTE The survey after development is the one that shows the screen slots clear, the casing joints sound, and the well bottom free of the sand the development pulled in, which is the condition the pump is set into; the open-hole survey shows the formation face in a rock well where the screen is to be set across fractures; the final survey records the well as it was released, which is the record an owner opens when the pump is pulled years later. (6.4.5)

NOTE Low-carbon steel is the casing of nearly every public supply well, welded in the field, driven or set to any depth, and left to a slow corrosion that a few decades of service in ordinary groundwater tolerate; stainless steel casing is set where the water is corrosive, where the Owner expects the well to outlast steel, or where iron pickup from the casing is a water quality objection, at several times the cost and with a joint that needs a qualified stainless welder; Type 316L adds resistance to chloride where the groundwater is brackish; PVC casing is light, immune to corrosion, admitted by most state codes for a well of moderate depth and diameter, and limited by its collapse strength under the grout and the formation, by the depth to which a plastic string can be set, and by a code that in some states does not admit it for a public supply well. (7.1.2)

NOTE A welded joint is as strong as the casing, adds nothing to the outside diameter, and is the joint of every casing larger than a hand can thread, at the cost of a welder on the rig floor for every joint and a weld that is made in the weather; a threaded and coupled joint is made up in minutes on a small-diameter casing, costs a coupling that enlarges the annulus the grout has to pass, and is the joint a driven casing on a cable tool rig is usually run with. (7.2.2)

NOTE A surface casing left in place is a second steel wall through the unconsolidated upper section and the one the code counts where it requires a cased and grouted interval to a stated depth, at the cost of a double annulus to grout; a withdrawn casing is pulled in stages as the grout rises behind it, so the seal is placed against the formation rather than against a pipe, and it is the position where the surface casing was temporary support for the drilling and the code does not require it to remain. (7.3.4)

NOTE A centralizer holds the casing off the borehole wall so the grout surrounds it, and a casing that lies against the wall has a seal on one side and a channel on the other; the spacing tightens where the hole is deviated or the casing is light, and it is not applied to a driven casing, which has no annulus to center in. (7.4.2)

NOTE Twelve inches is the floor most state codes set, 18 to 24 in. is what a public supply well with a surface discharge head is built to so the head stands clear of the pad, and a taller stickup is set where the well is in a floodplain, where snow lies against the casing, or where the well house floor is raised above the pad. (7.4.5)

NOTE Neat cement, portland cement per ASTM C150/C150M and water, sets hard, bonds to steel, and is the seal every state admits for every well, at the cost of shrinkage on setting that a bentonite addition is used to offset and of a heat of hydration that softens PVC casing in a deep sealed interval; cement-bentonite, with a few percent bentonite, shrinks less and pumps more easily; a high-solids bentonite grout stays plastic, follows the casing as it moves, does not heat, and is the seal many codes admit for a well outside a public supply and some admit for any well, and it cannot be placed where it will dry or where the formation water is saline enough to flocculate it; chips or pellets are poured dry and hydrate in place, which works in a shallow annulus above the water table and bridges in a deep or wet one; sand-cement grout carries more volume per sack for a large annulus and is admitted by some codes and not others. (8.1.2)

NOTE An inch and a half is the narrowest annulus a tremie pipe passes through and the floor most codes set, 2 in. is the common code figure and the width a coupling on a threaded casing needs, and 3 to 4 in. is set where a grout pipe is to be left in place beside the casing, where the formation caves, or where the code requires it for a public supply well. (8.2.4)

NOTE A tremie pipe lowered to the bottom of the annulus and kept below the grout surface as it is withdrawn places the seal from the bottom up in any annulus wide enough to pass it, and it is the method on most wells; pressure grouting through a pipe set to the casing shoe pumps the grout up the annulus from the bottom without a pipe in the annulus, which suits a narrow annulus and a deep interval; grouting through the casing displaces the grout out the bottom of the casing and up the annulus, leaves a plug in the casing that is drilled out after the grout sets, and is the method on a deep well where neither pipe can be placed. Pouring grout from the surface is not among them, because grout poured down an annulus bridges, dilutes in the standing water, and leaves voids the surface never sees. (8.3.2)

NOTE Twenty-four hours is the common code minimum for a cement grout, 72 hours is set where the casing shoe is to be drilled out or the string will be loaded before the grout has full strength, and 12 hours is admitted by some codes where an accelerator is used; a bentonite grout has no set to wait for and is held for the period the code states for it. (8.3.7)

NOTE A grout seal is the one component of a well that cannot be inspected after it is placed and cannot be repaired without abandoning the well, and the volume reconciliation and the returns at the surface are the only two facts that show it reached the bottom of the interval and filled it. (8.3.8)

NOTE A continuous-slot screen is a wire wound on rods with a slot that is accurate to a thousandth of an inch and an open area that no other type matches, so it passes the most water per foot at the lowest entrance velocity and develops the most completely, at the highest cost per foot and a collapse strength that limits it in a deep or caving hole; a louvered screen is punched from heavy pipe, is strong enough to be driven or set in a deep hole, and is the screen of the filter-packed wells of the arid West, where its lower open area is made up by a long screen in a thick aquifer; a bridge-slot screen is punched and formed from sheet, costs less than wire-wound at an open area between the two, and is set in a filter-packed well of moderate depth; machine-slotted pipe is a casing with slots sawn in it, has the lowest open area, the least accurate slot, and the lowest cost, and is admitted on a low-yield well where the aquifer is coarse enough that the slot is not the limit; a pipe-base screen puts a wire wrap over a perforated pipe, which carries the collapse strength of the pipe with the slot accuracy of the wire, and it is the screen of a deep well in a weak formation. (9.1.2)

NOTE Type 304 stainless is the screen material of nearly every public supply well, because the screen is the one component that corrodes from both sides and cannot be replaced, and its cost over steel is small against the cost of the well; Type 316 adds molybdenum for a brackish or sulfide water; low-carbon and galvanized steel screens are set in a short-lived or low-value well where the water is not aggressive and the cost of the screen is the deciding number, and they bring the incrustation and the slot enlargement that a steel screen suffers in iron-bearing water; PVC screen is immune to corrosion and is set in a shallow well of small diameter, and it cannot be developed as hard or set as deep as a metal screen. (9.1.5)

NOTE The screen design is made after the samples are sieved because the drawings were drawn before the hole was drilled: the slot is chosen to retain the filter pack or, in a naturally developed well, to pass the fine fraction of the aquifer and retain the coarse, and the setting is chosen against the logs so the screen sits in the sand and not in the clay above or below it. A slot chosen from the drawings passes sand for the life of the well or chokes it, and both are repaired only by a new well. (9.2.3)

NOTE An entrance velocity at or below a tenth of a foot per second keeps the flow through the slot laminar, so the pack and the formation stay where development left them and the incrustation that a turbulent slot accelerates is held back, and it is the figure the well design texts and AWWA M21 are written around; a higher velocity shortens the screen in a thin aquifer at the cost of sand movement and faster plugging, and a lower figure buys a longer screen in a well the Owner expects to run for decades. (9.2.5)

NOTE The sump is where the sand that passes the screen settles instead of accumulating in the screen, and it is also the length the well can be cleaned to before the screen is reached; 5 to 10 ft is the usual allowance on a municipal well, a longer sump is set where the formation is fine and some sand production is expected, and zero is the position where the code sets the total depth or the aquifer bottom is at the screen. (9.2.7)

NOTE A pipe-size screen is set as part of the casing string and seals to it at the joint, which is the arrangement of a well drilled to full diameter with the screen in the string; a telescoped screen is lowered through the casing after the casing is set and sealed to it with a lead or neoprene packer at the overlap, which is the arrangement of a cable tool well, of a well whose screen interval was not known until the casing was down, and of a screen that can later be pulled and replaced. (9.2.9)

NOTE A filter-packed well puts a designed sand or gravel envelope between the screen and the aquifer, so the slot is chosen to hold the pack and the pack is chosen to hold the formation, and it is the completion of a fine, uniform, or layered aquifer and of nearly every large municipal well in unconsolidated sand; a naturally developed well sets the screen against the formation and develops the formation itself into a graded envelope by pulling the fines through the slot, which costs nothing in pack and depends on an aquifer that is coarse and well graded enough to build its own filter. (10.1.2)

NOTE A pack whose median grain is four to six times the formation's holds the formation back while passing the water, a ratio above that lets the formation migrate into the pack and the pack into the screen, and a ratio below it chokes the well; the ratio is pushed to the upper end in a uniform formation and held low in a layered one, and a uniformity coefficient near 2.5 or below keeps the pack from segregating as it is placed and from building a layered envelope of its own. (10.2.4)

NOTE The pack settles as the well is developed and pumped, and the height above the screen is the reserve that keeps the top of the screen in pack rather than in grout or formation as it does; 20 ft is the usual allowance on a shallow well, 50 ft or more on a deep well where the pack is placed through a long tremie and settles further, and the fill pipe below is what replenishes it. (10.2.6)

NOTE A tremie places the pack from the bottom up at a rate the operator controls and is the method on a deep well, a narrow annulus, and any well where bridging would leave the screen in open hole; pouring from the surface is admitted by some codes on a shallow well with a wide annulus and a thin fluid, where the grains fall fast enough not to bridge, and it is the method a crew without a tremie reaches for on every well. (10.3.2)

NOTE A fill pipe is the only way to add pack after the seal is placed, and a well whose pack has settled below the top of the screen without one admits formation sand at the top of the screen for the rest of its life; it is omitted where the pack reserve above the screen is generous, where the annulus is too narrow for the pipe beside the casing, and where the code requires a grouted annulus that the pipe would penetrate. (10.3.6)

NOTE The dummy cylinder is a rigid section of pipe a little smaller than the casing, lowered on a line through the full test depth, and the plumb line is read at the surface against a template as it goes; it proves the one thing the pump installer needs, that a rigid body of the pump's diameter passes, and it is the method AWWA A100 describes. A deviation survey measures the inclination and direction of the hole continuously and plots the well in three dimensions, which is the record a deep well with a long line-shaft pump wants, and it does not by itself prove that a dummy passes. (11.2)

NOTE The pump is what the test protects, so testing to the setting depth with a margin is enough on a well whose pump will never go deeper; testing to the casing bottom records the full cased section for a pump that is lowered as the water level declines over the years; testing through the screen is set where the screen is pipe-size and a pump or a tool will pass into it. (11.4)

NOTE The pump the well is built for is a rigid column several hundred feet long hung from the surface, and a casing that drifts or doglegs binds the column, wears the bearings on one side, and in a submersible well pump holds the motor against the casing where it cannot cool; the test is made before the pump is bought because the alternative is a pump that will not go down. (11.7)

NOTE A surge block moved up and down in the casing drives water in and out through the screen and is the oldest and the most forceful method, effective in a naturally developed well and capable of locking a filter pack if it is used before the pack has settled; air-lift pumping lifts the water with compressed air and surges it by cutting the air, which develops and cleans the well at the same time and needs a compressor matched to the depth; jetting directs a horizontal water jet through the slots from inside the screen while the well is pumped, and it is the method that reaches the pack and the wall cake behind a continuous-slot screen most completely; overpumping at a rate above the design rate and backwashing by stopping the pump and letting the column fall is the gentlest method and the one every well finishes with; a dual-swab isolation tool pumps one section of screen at a time at a velocity no whole-screen method reaches, which is the method of a long screen whose lower sections never see flow otherwise. The plan sequences the gentle methods first and the forceful ones after the pack has settled. (12.1.2)

NOTE A dispersant breaks up the clay and the drilling fluid cake left on the formation face and is the chemical nearly every rotary-drilled well is developed with; acid dissolves the carbonate cement and the incrustation in a limestone or an iron-bearing formation and brings the handling, the neutralization, and the state's rules on acid in a well with it; chlorine at a development dose kills the bacteria the drilling introduced and breaks down an organic polymer fluid, and it is counted again at the disinfection, which it does not replace. Selecting none is the position on a cable tool well with no fluid to remove and on a site whose permit admits no chemical in the well. (12.1.5)

NOTE Five parts per million of sand at the design rate is the figure the well standards and the pump standards agree on, because it is the content the bronze bearings and the wear rings of a well pump tolerate for decades, and the pump standard reads it from the well record; a lower figure is set where the well feeds a membrane or a meter that sand damages, and a higher one is accepted on an irrigation well with a pump built for it. Turbidity catches the clay and the drilling fluid that a sand sampler does not, specific capacity stabilization is the sign that development has stopped improving the well, and the minimum duration is the floor that keeps a crew from stopping at the first clean sample on a well whose pack has not yet settled; the duration is set by the hydrogeologist against the method and the depth, with 24 to 48 hours the usual figure on a municipal well. (12.2.5)

NOTE A test pump that reaches half again the anticipated yield can run the top step of the step-drawdown test above the design rate, which is the step that shows where the well's efficiency falls off and sets the recommended production rate with a margin; a pump sized at the anticipated yield proves only that rate, and a pump at twice it is set where the hydrogeologist expects the well to outperform the memorandum. (13.1.2)

NOTE A storm drain takes the flow where one is within reach and the sediment control is sized for the pump rate; land application needs ground that will take a day or three of the test rate without eroding or ponding back to the well; a surface water discharge needs its own permit, and on a public supply test the chlorinated development water before it needs dechlorination; a sanitary sewer takes a chemically treated discharge the storm system cannot, where the utility agrees to the volume; a plant raw water system takes the water where the well is at the plant and the plant can accept an untreated source during the test. (13.1.6)

NOTE The orifice weir, a plate on the end of a horizontal discharge pipe read with a manometer tube, is the instrument of the well test as it has been run for a century, accurate to a few percent, and cheap, and it needs a full pipe and a level run; a calibrated meter reads directly, totalizes, and logs, and it is the instrument on a test whose data goes to a primacy agency that asks for a calibration certificate; a V-notch weir in an open channel serves a small well and a discharge that runs across the ground; timed filling of a container serves the smallest wells and the field check of any of the others. (13.2.2)

NOTE A transducer in the well logs the level every few seconds through the test and through recovery, which is the data a type-curve analysis of the aquifer wants, and it drifts, so the sounder reads the level by hand on the schedule and checks it; the air line is the instrument of a well whose pump column fills the casing, and the chalked tape is the reference every other method is checked against at the static level. Furnishing both the sounder and the transducer is what a test for a public supply well is run with. (13.2.4)

NOTE The step test separates the drawdown that belongs to the aquifer from the drawdown that belongs to the well, so the hydrogeologist can set the production rate where the well loss is still small; three steps are the fewest that define the curve, four or five give the fit a check, and the step is run long enough for the level to stabilize at each rate, which is an hour in a transmissive aquifer and longer in a tight one. (13.3.3)

NOTE The rate and the duration are the hydrogeologist's: the rate is set against the anticipated yield and the step test, and the duration against the aquifer, the boundaries the hydrogeologist wants the drawdown curve to reach, and the floor the primacy agency sets for a new source, which is a day on most public supply wells and three days where the agency wants to see the well through a boundary or the Owner wants a yield it can rely on in a drought. Neither has a norm a standard can assert. (13.4.3)

NOTE Recovery is the second half of the test and the half that costs nothing to run, because the aquifer recovers on its own schedule and the transmissivity read from the recovery curve checks the one read from the drawdown; a short recovery is set where the aquifer is transmissive and recovers in hours, and a day or two where it is tight and the hydrogeologist wants the full curve. (13.5.2)

NOTE The sample is taken at the end of the test because the water that arrives first is the water that sat in the well and the pack, and only after a day of pumping is the discharge the aquifer's own; the list is the agency's because it is the agency that decides whether the well is a source, and the memorandum adds the parameters the plant's treatment is designed around. (13.6.5)

NOTE The hydrogeologist's report is the one the primacy agency and the pump selection read, because the recommended rate and the pump setting are a judgment about the aquifer and the Owner's exposure, and the driller's report is the field data with that judgment added in review on a small well where the driller runs the analysis as a matter of course. (13.7.2)

NOTE The well record is the handoff between two trades that never meet on the site: the driller is gone when the pump installer arrives, and the casing diameter, the pumping level, the sand content, and the plumbness result on that one sheet are everything the pump installer knows about the hole the pump is going into. (13.7.5)

NOTE Calcium hypochlorite is carried as a dry solid, dissolves in the well as it is placed, and is the form a driller stocks; sodium hypochlorite is a liquid that is mixed at the surface and poured or pumped in a known concentration, which is easier to dose accurately in a large well and degrades in storage, so its strength is checked before it is used. Both forms are what C654 is written for. (14.1.3)

NOTE Fifty milligrams per liter is the floor C654 sets, 100 to 200 is what most state codes and hydrogeologists specify for a new well, whose pack and formation face consume chlorine that a clean distribution main does not, and a higher dose is set where the development used an organic polymer or the bacteriological samples have failed once; the contact time trades against the dose, with a day the usual figure and a shorter contact admitted at a higher concentration where the code allows it. (14.1.7)

NOTE One sample is the release a private well program accepts, two consecutive samples a day apart are what most primacy agencies require of a new public supply source, and three are set where the agency or the Owner wants a clearance that a single borderline result cannot pass. (14.2.2)

NOTE An above-ground discharge puts the discharge head, the sanitary seal, and the first valve on top of the casing inside a well house, where they can be seen and serviced, and it is the arrangement of a line-shaft turbine well and of any well in a building; a pitless adapter or unit carries the discharge out through the casing wall below frost, with the casing sealed to the unit and the cap above grade, and it is the arrangement of a submersible well with no building over it. (15.1.2)

NOTE The driller installs the pitless unit as part of the wellhead when it is a weld-on unit set into the casing before the pad is poured, which is the usual sequence where the casing is steel and the driller is on the site; the pump manufacturer furnishes it when it is matched to the pump column and the discharge head, which is the position Vertical Turbine PumpsVertical Turbine PumpsResolves to the current adopted revision.sync/vertical-turbine-pumps takes where the drawings assign it there. The field settles which, so the two standards do not both furnish it. (15.1.4)

NOTE A three-quarter-inch tube passes an electric sounder probe, a one-inch tube passes most transducers, and a larger tube passes a transducer with its cable and leaves room for a second instrument, at the cost of annulus between the pump column and the casing that a tight well does not have; the tube is the only route to the water level once the pump is in, and the level in the well is the number that tells the Owner the aquifer is declining. (15.2.4)

NOTE Two feet is the pad a state code requires around a private well, a 3 to 4 ft pad is the usual finish at a public supply wellhead outside a building, and a larger pad is the floor of a well house or the apron a crane sets up on to pull the pump. (15.3.2)

NOTE A well is a direct path from the surface to the aquifer with no soil between to filter what goes down it, and a well that is contaminated during construction is contaminated for the life of the aquifer it penetrates; a cap, a setback, and a pit that is where the plan says it is are the whole of the protection. (16.6)

NOTE A hole left open after it has failed is the conduit between aquifers and the surface that every other clause in this standard exists to prevent, and the code requires its abandonment for that reason rather than as housekeeping. (17.6)

NOTE The state well completion report is the public record of the well, and it is the document the next hydrogeologist on the aquifer, the next driller on the site, and the state well program read when the well is deepened, rehabilitated, or abandoned decades after everyone who built it is gone. (18.5)

NOTE A one-year period matches the general warranty of the construction contract and covers the first year of pumping, in which a pack that was going to settle has settled and a seal that was going to leak has leaked; a longer period is set where the Owner has had a well fail on earlier work, where the well is deep, or where the Owner wants the sand warranty to run past the first drought summer. (20.2)