| Water Stuff; Originally posted by Hawker | |
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| Tweet Topic Started: May 27 2009, 08:25 PM (369 Views) | |
| CindyLou62 | May 27 2009, 08:25 PM Post #1 |
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The following posts are posted courtesy of ConSigCor and the authors of the articles.... Water: a safe supply when you're off the grid By Jeffrey Yago, P.E., CEM That remote mountain property seemed like a steal until you found out you could not drill a well. Four years ago we were approached by a professional couple from a major city, who had just purchased property in the very remote mountains of Idaho. After selecting the perfect site to build their dream retirement home, their well driller came up dry after drilling multiple wells over 500 feet deep. Although their site included a spectacular view of a fast moving Idaho stream, this water passes through a wilderness area which is home to bear, elk, and fish all sharing this same water supply. Since there is a potential for water contamination from both animal wastes and decaying material, and hauling drinking water miles from the nearest town did not seem practical, an alternative water system was needed. At one time or another, almost all of us have quenched our thirst directly from a stream in the woods, but an occasional drink does not offer the same health risk as permanently supplying all residential drinking, washing, and food preparation water needs from an untreated water source. Although a large segment of the world’s population still uses untreated surface water for their daily needs, water related illnesses are increasing dramatically as population density and waste levels rise. Recent media stories of widespread illnesses caused from eating unwashed fruits and vegetables are now commonplace, and soap alone is not effective if the rinse water is untreated. Just when the lack of an adequate water supply for this home was developing into a major problem, we were completing the design of the solar energy system to power this off-grid dome home. When it became apparent the water issue could jeopardize the entire project, we began contacting manufacturers of water treatment equipment for a solution. Although there are many commercial water purification systems on the market, most are either too large or require more electricity to power than most off-grid solar electric systems can provide. After further analysis, we designed the simplified site built system shown in the accompanying piping diagram. Initially, a local backhoe operator dug out an area along the creek bank and buried four 3-foot diameter concrete culverts stacked on top of each other. Being in creek gravel, this infiltration well quickly filled with water from the creek and provided an unlimited supply of untreated water for pumping up to the home site. Unfortunately, a major rain upstream caused a significant storm surge which totally carried away everything but the end of the wiring that had been connected to the two now missing (and expensive) submergible pumps. We wanted to avoid using a skimmer type inlet due to the constant need to remove debris and high risk of damage from this fast moving stream. Therefore, a shallow drilled well, approximately 30 feet deep, was located higher up the creek bank. This shallow depth well in loose rock near the creek also quickly filled with surface water, but was no longer in danger of storm damage. Now with a good source of untreated water established, it was time to design a low energy water purification system. Pumping system design Pumping water requires lots of energy and AC pumps would require operating a generator all day due to the very limited capacity of the planned solar photovoltaic system. Therefore, a two-stage low pressure/high pressure pumping design was developed with two pumps installed in the shallow well. Near the bottom, a slow flow 24-volt DC Solar Jack pump was installed which supplies a slow but constant water flow throughout the day from the shallow well up to the higher elevation home site. A 120-volt AC pump was installed higher in the well, having a high flow rate and powered directly from the generator. Due to the danger of forest fires and occasional garden watering needs, it was decided this two pump design provided both energy efficient low flow and emergency high flow requirements. Since it takes most of the lift capacity of the slow flow DC pump to raise the water from the well up to the ground floor elevation of the new house, this low pressure flow could not be connected directly into the home’s plumbing system which requires short periods of high pressure flows throughout the day. A 500-gallon 3 foot-high by 5 foot-diameter 5/16-inch wall plastic storage tank filled directly from the low flow well pump was installed in the ground floor utility room. A pre-filter was installed in the piping from the well to the storage tank after finding that the creek water was usually cloudy and would deposit sediment in the tank which required monthly clean out. A ball float switch is used to activate the DC well pump when the water level in the tank is low, and turn off when full. We soon determined the 500 gallons of water storage did not cycle the tank satisfactorily with a low pump flow, so the water level was lowered to approximately 300 gallons which provided much better tank cycling. The 300 gallons of stored water seems to easily meet an average home’s water requirements for several days. This slow pump and storage tank design combination would also help solve capacity problems with sites having slow recovery deep drilled wells, by using a second pump and a tank as a buffer. The generator-powered AC pump is not used to refill the storage tank, although a hand operated bypass valve allows backup filling if the slow pump fails. A Dankoff high-pressure pump powered by a high efficiency 24-volt DC motor was connected to a bottom fitting on the storage tank. This pump is extremely energy efficient and has a very low power drain on the solar charged batteries, but its close mechanical tolerance requires a particle filter between the tank and the pump inlet to remove pump damaging sand or grit. This DC pump supplies the home’s conventual plumbing system from the storage tank once the water has passed through the site built filtering system. All pumps require a very high initial in rush of electricity to start pumping from a no flow state. By using a very large expansion tank, all pumps will run longer after startup, but will also stay off longer before system pressure drops. This significantly reduces short cycling of the pumps, which reduces both pump wear and electrical system demand. Low energy water filter After the stored water has left the tank and passed through a sand filter to remove all solids and particles, this water passes through dual carbon cartridge filters. Only one carbon filter is in use at a time, and the flow can be quickly valved over to the second carbon filter allowing filter replacement as needed. The carbon filters remove all taste related problems associated with many well water systems, and also reduce minerals that can cause scale buildup on plumbing fixtures. Replacement cartridges are also available to remove lead if needed. At this point the water is as mechanically clean as possible, but microscopic bacteria can easily pass through even multiple stages of mechanical filters. The final stage of water purification is an ultraviolet water purifier. This unit includes a 254-nanometer wave length ultraviolet light at the correct intensity to kill all bacteria, mold spores, protozoa, viruses, and pathogenic microorganisms typically found in untreated surface water. This innovative device consists of a stainless steel cylinder having a water inlet and outlet at each end. Down the center is a high pressure quartz glass tube containing an ultraviolet fluorescent tube lamp. Due to the narrow water chamber formed between the outer glass wall and the inner steel cylinder, all of the water passes closely around and along this ultraviolet lamp before exiting. Keeping water flow under 7 g.p.m. allows more than enough exposure time to kill all micro-organisms. Commodes, yard hydrants, and laundry equipment not requiring this level of water quality can be connected to the pressurized system at a point ahead of this filter. List of material sources: Off-grid solar electric systems Dunimis Technology Inc. 804-784-0063 www.dunimis.com High Quality high pressure DC powered pumps Dankoff Solar Products 505-820-6611 www.danksolar.com Solar Jack Submersible DC powered well pumps Kyocera Solar Inc. 800-544-6466 www.kyocerasolar.com Series 8101-GUS 7 gpm Ultraviolet Water Filter Ultra Dynamics 201-489-0044 www.capitalcontrols.com 525 gallon high density polyethylene tank Poly Processing Company 318-343-7565 www.polyprocessing.com Teel expansion tank and sand filters Grainger Supply 1-800-323-0620 www.grainger.com It should be noted that testing of ultraviolet light filters has shown some bacteria can “swim” short distances past the light after flow has stopped and the light turned off. Some models now include a quick action automatic valve to address this issue. Note the flow switch located to the left of the ultraviolet water filter shown in the photo which was designed to turn off this unit as soon as water flow was stopped to reduce energy use. Although we were careful to use a very high quality and sensitive flow switch, we still had concern that the water system could be contaminated if this light ever failed to turn on quickly. After determining that the solar charged battery system had the capacity to operate the low wattage lamp continuously, the homeowner now unplugs this unit only during winter system shut down and system draining. The pumping diagram shows how both well pumps supply the filtering system through individual check valves. This was necessary to insure garden watering would not quickly back drain the storage tank. Garden watering should only take place when the generator is operating to power the AC pump directly. The manual bypass valve shown piped around the check valve in the AC pump line allows the pressure switch controlling the AC pump to “see” the yard faucet pressure drop. Without this manual bypass, this pressure switch would shutoff the AC pump once the home’s domestic water system was at full pressure, even if all yard faucets were wide open. Hot water To complete this low energy domestic water system design, an instantaneous AquaStar tankless propane hot water heater supplies more than enough hot water without electricity. An internal mechanical gas valve opens as soon as water flow is detected, which quickly heats the water flowing through a stainless steel water coil surrounding the gas burner. Conclusions Although using two or more pumps and a large un-pressurized holding tank at first appears to be complex, this system offers solutions to many off-grid domestic water problems including: • Maximizes performance of very slow recovery wells. • Allows utilizing surface, pond, and creek water sources where safer deep wells are not practical. • Provides substantial reductions in pumping electrical energy over a typical AC submergible well pump system. • Low energy pumps can be powered directly from a solar charged battery without using an inverter. • The optional AC pump powered directly from a generator allows occasional garden watering and emergency high water flows from yard faucets without overloading the solar energy system. Since water quality is becoming a hot button issue for this country, a low energy solution is needed for off-grid homes. The system described in this article should provide very good health protection when using surface water. However, each water source is different and should be tested prior to final filter equipment selection. The storage tank also offers an ideal point to add Clorox or iodine treatment on a regular schedule for those really difficult water quality issues. Jeff Yago is a licensed professional engineer and certified energy manager with over 25-years experience in the energy conservation field. He is also certified by the North American Board of Certified Energy Practitioners as a licensed solar installer and a licensed journeyman electrician. He has extensive solar thermal and solar photovoltaic system design experience and has authored numerous articles and texts. Build your own solar-powered water pumping station By Jeffrey Yago, P.E., CEM In the last issue, there was an excellent article by Dorothy Ainsworth on water pumping using mechanical windmills. In this issue I will address another form of “free” water pumping. There are many remote applications where a solar-powered water pump is more cost effective than installing a conventional grid-connected AC pump. I recently designed a solar-powered pumping system for a local farmer wanting to pump water from a lake up to a watering trough for cattle in a distant fenced field. We have also designed larger systems to pump directly from drilled wells up to elevated storage tanks, which provide gravity-fed water back down to remote ranch buildings. Basic system description These solar applications made economic sense because the location was too remote to run a long power line. A solar-powered water system is one of the easiest solar power systems to install, since you will not need a battery or battery charging equipment. When the sun is shining, the system is pumping, when the sun is not shining, the system is off—simple. By adding a storage tank and increasing the size of the pumping system, excess pumped water can be stored, which can continue to supply water during the night or when it’s cloudy and the pump is off. Low voltage DC pumps designed to operate on solar power are not designed like 220-volt AC water pumps. A DC water pump is designed to pump using the absolute minimum of electrical power. Unfortunately, this also usually means a very low flow rate, so having a storage tank or open trough is essential. Although the flow rate can be less than one gallon per minute (GPM) for the smaller pump sizes, this small flow will be fairly constant throughout the solar day (9 AM to 3 PM for most locations). This low flow rate can still provide over 350 gallons of water per day from all but the deepest well applications. A solar module can be mounted almost anywhere, but should face in a southerly direction (for North America). Most farm and ranch applications should have the modules and pump controller mounted on a raised pole to stay above snow drifts and potential damage from animals. A pole mount also allows easier adjustment of module tilt and east-west orientation during initial setup to achieve the best overall year-round performance. For most applications the tilt will be equal to your latitude. Pump controller Your solar powered pumping system should include a pump controller such as the one in the photo on page 37. Although it is possible to connect the pump leads directly to the output terminals of the solar module, a controller provides much better pump performance and start/stop control. It will also avoid trying to operate the pump in a stalled condition when solar output is too low. Each residential-size solar module will produce a fairly constant 17-volts output at almost any level of sunlight. However, the current output (amps) will be directly proportional to sun intensity. The pump will have a minimum current draw when stalled and no pumping is taking place. As the voltage is increased, pump rotation and water pumping is increased as long as enough current is available. During less than ideal solar periods, the current output of the solar module(s) can be below the amp draw required for the pump to begin pumping. A solar pump controller will convert any excess voltage of the solar array to more output current. The resulting lower voltage will not provide the normal flow output from the slower turning pump, but it will allow reduced flow during those hours the pump will normally be “stalled.” In addition to matching the voltage and current load of the pump with the charging current and voltage output of the solar module, a solar-pump controller also includes wiring terminals for normally open (n.o.) and normally closed (n.c.) switch contacts. This makes it easy to add a high and low level float switch to the storage tank, or a low-limit float switch for the well or pond providing the water source. The following information is taken from my book titled, Achieving Energy Independence—One Step at a Time. You might find this book helpful if you are considering installing your own solar power system, and it goes into much more detail than space allows here. Table 1 will get you started by estimating how much water you will need per day. Table 1 will get you started by estimating how much water you will need per day. Since your pump will not work during cloudy weather, be sure to have a tank or trough that can hold several days’ usage. Pumping basics Any well or pressure pump is designed to provide a given flow of water (GPM) for a given pressure or lift (head). Pumping “head” is measured in feet, and represents the total lift the pump can raise water from a low point to a high point. When measuring the distance a submerged pump must raise water, you do not start with how far down the pump is in the well. You start by measuring from the above ground surface down to the lowest level the well water will be during pumping. For example, let’s say we want to fill an open water tank (no pressure) that is on the top of a small hill. We estimate that the water level in this tank will be 3 feet high above ground level, but the hill top is 50-feet higher than where the well is going to be drilled. The well will be 100 feet deep and the pump will be positioned 80 feet down. We notice the water level is only 30 feet below the surface, but will probably drop considerably when the pumping starts unless it is a very fast refilling well. If your well driller cannot provide this information, you will need to estimate how much “draw-down” the well will have during pumping. For a fairly fast recharging well, let’s add another 20 feet for this estimated draw-down. For our example, the pump would need to have a minimum lift of (30 feet + 20 feet to lowest water level) + 50 feet elevation of the tank + 3 feet tank water depth = 103 feet total pumping head. If you want to convert feet head to pounds per square inch (PSI) pressure, divide by 2.31 which equals 45 PSI (103/2.31). If your tank will be closed and pressurized, you will need to add the desired tank water pressure to this pump’s head pressure. Instead of a deep well, you may need to pump from a lake or pond at a lower level up to a storage tank. The pump lift estimating procedures we used in the above deep well example also applies. However, you measure from the lake’s surface level, regardless of how deep the pump will be below the surface. When using a large body of water as a water source, you will want to suspend the pump off the bottom using an underwater support or surface floats to avoid plugging the pump intake with mud from the bottom. Another common mistake to avoid, is do not oversize the piping. For most applications, you will be pumping less than two GPM, and at this low flow rate, these low flow solar pumps will not provide enough water velocity through a large pipe to keep suspended solids from settling out onto the bottom of the piping. A typical residential size 1/2-HP deep well pump can pump over six GPM, which produces a much higher velocity. For these larger flow AC pumps, larger pipe sizing is used to keep flow resistance low on long piping runs. However, for a low-flow solar pump for applications requiring less than 100 feet of piping, a 1/2-inch PVC pipe size will probably work just fine. For runs over 100 feet, I suggest using 3/4-inch PVC piping. If you need to pump water over 300 feet, a 1-inch pipe size will lower the high pressure drop of the smaller pipe, but you may have problems with sediment settling in the bottom of the pipe due to the low flow rates involved. Remember, the purpose of the storage tank or drinking trough is to allow a very slow water flow constantly pumping throughout the day, to build up a large volume of water to supply brief periods of high water usage. Solar module sizing You may want to consult the DC pump distributor to determine the size of solar array that will be required for your specific application. For high pumping heads (feet of lift) or high flow rates, you may want to consider buying a higher voltage DC pump instead of a smaller 12-volt DC pump. This will require using two or more nominal 12-volt solar modules to provide the higher voltage. To get you started with solar array sizing, it is rare that any solar-pumping application can get by with less than a 75-watt solar module, and larger applications will require two modules for acceptable pump performance. A 48-volt DC pump will require a minimum of four nominal 12-volt solar modules (4x12). The installation shown in this article supplies water to a cattle drinking trough located 75 feet higher than a nearby lake, which is 300 feet away. We used a 24-volt DC Solar Jack TM pump, two Kyocera 60-watt solar modules, and 320 feet of 3/4-inch PVC pipe. The photos were taken in late October after 6 p.m. and the panels were no longer facing the setting sun, yet there was still almost 1/2-gallon per minute flow of fresh water up to the trough. Piping head loss In addition to the elevation head (feet) your pump must lift the water from a low pond or drilled well up to a storage tank, Table 2 provides piping resistance to flow in terms of head (feet).it also must overcome the resistance to flow of the pipe. As I stated earlier, for small-flow DC pumping applications, if you oversize the piping to reduce friction loss, you could increase sediment problems at these low flow data rates. Table 2 provides piping resistance to flow in terms of head (feet). This makes it easy to calculate total pump size, by adding this pipe friction head loss to the lift head we estimated earlier. As an example, let’s say you need to calculate the piping pressure loss for a 2-gallon per minute flow through 250 feet of pipe. If we use 1/2-inch PVC pipe, the loss would be 8.9 feet head (3.56 x 250/100). If we increased the pipe size to 3/4-inch PVC, the loss would be 2.3 feet head (0.90 x 250/100). At this low flow rate either pipe size will work, unless your pump cannot handle the additional pressure loss of the smaller pipe. As flow rates increase, a larger pipe may be unavoidable on longer pipe runs. Pump selection Table 3 provides a size comparison of several popular models of smaller DC pumps, and the relationship of pump flow (GPM) to pump head (feet). Notice how the same pump will have a substantially reduced flow rate as this head pressure is increased. Table 3 provides a size comparison of several popular models of smaller DC pumps, and the relationship of pump flow (GPM) to pump head (feet).Since this is only a very limited list of pump models and brands available, please consult the dealer for more specific sizing information. The manufacturers listed in Table 3 offer many other pump models having many different combinations of DC voltage, flow rate, and head or lift. Selecting the right pump for your specific application can reduce the size and cost of the solar array that will be required to provide the power. Buying a low cost pump with poor efficiency will require a much more expensive solar array. Solar pump suppliers Dankoff Solar Pumps www.dankoffsolar.com Backwoods Solar www.backwoodssolar.com Real Goods www.realgoods.com Build a 6500-gallon concrete water tank for $1500 By Dorothy Ainsworth Dorothy Ainsworth When I bought 10 dry barren “affordable” acres back in 1981 I got what I paid for: No electricity, no septic system, no well, and no water. What I did get was a long narrow rectangle carpeted with star thistle and poison oak, situated on the southern face of a hill (500'x1320'). Buying bare land was a big gamble, but I wanted my own piece of dirt so badly, I could taste it—if only I had some water to wash it down with. Thanks to the local well driller and good ol’ Mother Nature, I got that drink of water. I lucked out and struck it rich with a 50 GPM well at a depth of 150 feet for $3,000. The finished tank house The next steps were basic. I procured the appropriate permits, built a pump house around the well casing, set a power pole, wired in an electrical box and meter, and called the inspector. When all my lifelines were hooked up, I installed a submersible pump from Sears by following the do-it-yourself instructions, and to my amazement, when I turned on the control box, water spewed right up out of the pipe! Now I could get serious about improving the property. I’d start with a water storage tank because I believe “you are only as secure as your water supply.” To take advantage of gravity for water-on-demand, the logical place to put a holding tank was at the top of the hill, with the well at the bottom. I called a backhoe man to dig a 3' deep trench 1/4-mile long and level a spot at the top end for a 12'x12'x6' concrete tank (6500-gallon capacity). The 2hp submerged pump in the well would fill the tank via an 1-1/2" PVC pipe buried in the trench. When the tank was full, I’d use the same pipe to gravity feed water to supply all my household and irrigation needs. Every 60 feet down the line, I would put a 1" PVC riser sticking up out of the main pipe and cap it with a non-siphoning valve for irrigation. I would later put in 1" PVC pipes underground off of that main line as needed to supply my various structures as I built them. With a holding tank I would have the security of a week’s or month’s supply of water at a time (depending on the season) if the electricity went off for any reason. A stored supply would also save the pump motor from having to cycle on and off whenever a faucet was turned on. My storage tank would fill up in about 4 hours, then the pump would rest, and the well would replenish itself. It sounded like a good plan, so I got busy hauling gravel. I would need tons of it! I found a source for cheap crushed gravel (3/4 minus, meaning no rocks bigger than 3/4"), but, again you get what you pay for—I had to load it myself. I hauled a yard or two a day in my pickup until I stockpiled enough to build the tank. I had it down to a science: Each load took 300 shovels full. When the tires were flattened “just so,” I knew that that amount of too much was just enough. I’d creep home, front end floating, turn into my driveway, and step on it full throttle to get a run at the hill, fishtailing all the way to the top. (I had no roads yet.) Poor old “Bessie,” my 1971 1/2-ton Ford pickup, has endured cruel and unusual punishment for 20 years, hauling a hundred 1-ton loads of gravel for roads and 780 logs for houses, but she’s still going strong. It took two weeks of shoveling rock to have enough for the job, but loading and unloading the truck 20 times was just the half of it! Each of those 6,000 shovels full of gravel would have to be lifted again—either thrown on the ground to level the pad, or heaved into a cement mixer with sand and cement and water, then dumped and tamped into forms. I looked forward to the day when the “cruel gruel” would be entombed forever. The floor I had no electricity on top of the hill, so I borrowed a cement mixer and a gas-powered generator from a neighbor. He was a Bill-of-all-trades who also did everything the hard way to save money. I paid him what I could to help me with the general layout of the tank site, which consisted of setting up batter boards and making sure everything was plumb, level, and square. I covered the large pad where the tank would sit with about 8" of gravel. Then we built the forms out of 2"x8" lumber, set the 2" PVC drain pipe in place, and poured the 8" thick floor in two grueling days (32 mixers full = 4 cubic yards). We used a garden rake and a shovel to evenly distribute the mix around and work it into every corner. Together we dragged a 2''x6'' on edge across the surface of the wet concrete floor using the tops of the forms as guides—a procedure called “screeding.” Bill advised me to use no rebar in the slab because it would be filled with water inside and sitting on wet ground outside, and the rebar would eventually rust, leaving voids that would weaken the concrete. Right or wrong, I had no experience to question him, so that’s how we did it. Before the floor set up as hard as a rock, we roughed up the sides of the slab and a 2" wide strip around the top perimeter to serve as a keyway (an overhanging lip) to help tie the vertical walls to the floor. We used 5/8" plywood nailed to 2"x4" frames for the 8" thick walls. I sprayed the sheets of plywood with petroleum oil (using a garden sprayer) so they wouldn’t stick to the concrete when it was time for removing and repositioning them. Keyway to tie walls to floor We secured vertical rebar at 2' intervals inside the wall cavities. Bill helped me with the floor, but then he had to go to another job, so I carried on solo. A cubic yard and a half of concrete was all I was physically capable of shoveling, pouring, distributing, and tamping in 12 hours. I let each daily pour set up, then moved the forms up and raised the cement mixer platform and piles of ingredients to the new level. Bill stopped by on his way home from work each day to help me lift the heavy stuff. A series of separate pours meant “cold joints”—the lines of demarcation between pours. If the preceding surface is roughed up while the concrete is still “green,” the next layer bonds just fine. It’s not as ideal as a monolithic pour, but it was the only doable method for me. The recipe There are three basic mixtures that are commonly used for concrete construction, from strongest to strong enough. They differ in the ratio of the three basic ingredients: Cement, sand, and stone. How they are proportioned makes a huge difference in strength and durability. The more cement used, the stronger (richer) the mix, with 1:2:4 being a happy medium for most projects. The less water you can use in relation to the dry ingredients and still maintain a workable consistency, the stronger the mix. A runny mix is weak. The consistency of fresh mixed concrete should feel like oatmeal cookie batter—but don’t lick your fingers. The trick is to not touch the mix at all with bare hands, but for a novice, that’s easier said than done because it’s tempting to catch the drips and smear them around. Because Portland cement has abrasive silica and caustic lime in it, I ended up with no fingerprints at all until the “tread” grew back. It would have been a good time to take up a life of crime, but I stayed on the straight and narrow—and plumb. When you make a batch of concrete, the sum total of the ingredients mixed together will result in a much smaller volume than the separate components—kind of like what happens to that mountain of flour when you make a loaf of bread, or when you can’t believe you just used a 1/2-gallon of ice cream to make only two decent-sized milkshakes. Bill advised me to use a 1:3:5 mix: 1 heaping shovel of cement to 3 of sand, and 5 of gravel. For me, that mixture would be economical for my budget and yet strong enough for my particular application: a heavy foundation and thick retaining walls. Because the tank would be sitting on impenetrable hard rock, I knew it would have to be back-filled to bury it partially underground, which would also help equalize the pressure on the walls. (Water weight pushes out; wall of dirt pushes in.) Backfilling would also keep the water cool in the summer. Calculating what you need Using some simple math, I estimated the walls would take 8 cubic yards. Here’s how: Multiply length (12') x height (6') x thickness (3/4 of a foot = .75) x 4 walls and divide by 27 because there are 27 cubic feet in one cubic yard. The walls The growling gyrating cement mixer held 1/8 cubic yard (approximately 3.5 cubic feet) at a time, gobbling up 2 shovels of cement, 6 shovels of sand, 10 shovels of gravel. I worked as fast as I could slinging them in, counting and alternating the ingredients very carefully, while constantly adding the water with a measuring bucket (about 4 gallons). When the batter was “just right,” I shut off the motor, swung the cement mixer around on its axis and dumped the load into the forms, then tamped, tamped, and tamped with the business end of a short shovel. I also tapped the sides of the forms with a hammer to vibrate the concrete into every nook and cranny. On the fifth and final pour, I set a pipe through the wall near the top to make an overflow hole. I would later run a 1-1/2" poly-pipe through that hole and out to my pond. Each daily pour amounted to 12 mixers full, which totaled 24 shovels of cement, 72 shovels of sand, 120 shovels of gravel, and 48 gallons of water. I guzzled another 10 gallons of water and dumped even more on my head. It took five days of working from daybreak to backbreak to complete the walls. The whole project had to be a marathon because concrete sets up fast in extreme heat, and time was running out on my week vacation from waitressing. Needless to say, I put my fitness center membership on hold for a while. Sixteen Tons by Tennessee Ernie Ford was my theme song for the week, although the tank ended up weighing 24 tons. Blistered hands on Monday had turned into lobster claws by Friday. The roof On top of the last pour, I dragged a short 2''x6'' on edge across the 8" wide wet surfaces to smooth them out. I then set four 2"x4" pressure-treated sill plates in the concrete and leveled them with a long level by tamping and wiggling them into place around the outside perimeter, making sure the corners were squared. They would be an integral part of the roof construction, providing a wood surface to build a short stem wall on. The “pony wall” would be screened for cross-ventilation, rather than covered with plywood. I built a gabled roof on the tank, with the rafter tails secured to the top plate of the stem wall. (See photos) When the job was done (floor AND walls), I had used approximately 55 sacks of Portland cement, 6 cubic yards of sand, 10 cubic yards of gravel, and about 400 gallons of water. Not exactly like building Hoover Dam, but it felt like it. I kept the concrete slab and walls wet while they were curing by spraying everything down with a hose, including myself, as often as possible. I had a hose hooked up to the inlet/outlet pipe in the floor of the tank so water was handy. Note: This mandatory procedure should go on for at least a week when working in hot weather. Sealing the tank I think the reason my tank has held up so well for 23 years now, in spite of the 1:3:5 “poorman’s mix” I used, is because I coated the inside of the tank with a cohesive sealer called “Thoroseal.” Thoroseal is a Portland-cement-based coating that, when mixed with a milky-looking catalyst called Acryl 60, fills and seals voids and waterproofs the concrete. It prevents any water seepage from leaking into fissures where it might freeze and expand and crack the concrete. It also resists hydrostatic pressure (as inside a water tank) and is non-toxic in potable water tanks. It can be brushed on, but Bill advised me to trowel it on about 1/4" thick for an impenetrable bond. It took a lot of elbow grease applying it in smooth swipes on the entire inside surface of the tank, but it covered up all those rough cold-joint seams and made it look as smooth and beautiful as a baby-elephant’s butt. I don’t claim to be an expert on the subject of concrete tank building. We built the tank during possibly the hottest July in history, so my memory of the details may be a little off due to sunstroke. All I know is that I built it under Bill’s tutelage, and it has stood the test of time. When I look up the hill and see the water-level flag sticking up out of the tank’s roof and dancing in the breeze, it helps to quench my thirst for security and self-sufficiency. Back in the summer of 1983, the finished tank with its shingled roof cost me a total of $750 to build, including the lumber and plywood used for the forms. Today’s average prices Ingredients to make the concrete: * 80 lb. bag of Portland cement = $2.50 * Cubic yard of “construction sand” = $15 * Cubic yard of crushed gravel (3/4 minus or pea gravel) = $10. * Note: You can buy construction-grade sand and gravel already mixed in the ratio you want at any large rental equipment yard or your local sand and gravel supplier for about $32/yd. or $350 for a 10-yard dump truck full, delivered to your site. That sure beats the way I did it. Having the raw ingredients delivered would have been heaven instead of “the other place!” Framing and roofing lumber: * 2x8s = .70/ft. * 2x6s = .50/ft. * 2x4s = .35/ft. * 5/8" CDX plywood for roof = $18/sheet * Roof: I recommend composition roofing (cheap) or metal roofing (fireproof). I used cedar shingles back then, but now I would choose metal roofing and also divert the annual rainfall via rain gutters into the tank to supplement the supply. Total materials it takes for a 6500-gallon tank: * 55 bags cement = $140 * 5 yds. sand = $75 * 10 yds. gravel = $100 * 2 yds. gravel under pad = $20 * Forms: (40) 2x4 x12s = $168 * (8) 2x8x12s = $67 * (12) sheets of 5/8" plywood = $216 * Stem-wall: (12) 2x4x12s = $50 * Roof: (20) 2x6x8s = $112 * (12) sheets of 5/8" plywood = $0 ( I recycled the same plywood I used for the forms) * Assorted screws and nails and drain hardware: About $50 * Thoroseal: (10) 50-lb. bags to cover 500 sq. ft.= $250 * Acryl 60: 5 gallons = $125 * Composition roofing to cover the 200-sq. ft. roof = about $50 * Labor cost = your energy (a renewable resource) * Strong back = fringe benefit * Optional cost of labor if you treat yourself to pizza and beer to celebrate when the job is done = $20 Conservation tips When you live on well water and have to pump every drop, here are some astonishing figures to consider: A running faucet uses 3-5 gallons a minute. A running faucet while you brush your teeth can use 5 gallons. A running faucet while you do dishes can use 30 gallons. Washers use 30-60 gallons for each cycle. Wait till you have a full load of clothes before doing the laundry. A long shower can use 50 gallons. You’ll know it was too long when you run out of hot water. You’ll know it was way too long when you run out of cold water. The same tank today adds up to $1,500; still not bad for a permanent 6500-gallon water tank. I say “permanent,” but now I have my doubts after overhearing an old timer at the hardware story drawling to another old timer: “There are two kinds of concrete—concrete that’s cracked, and concrete that’s gonna crack.” Then they cackled and wheezed. Closing thoughts Any able-bodied person can mix and pour concrete. Building the forms to contain and shape it is the easiest and most elementary carpentry going. So, even though my cave-woman ordeal with concrete might sound difficult, don’t be intimidated by the “stuff.” It’s malleable and infallible. My style is to overbuild everything; it needn’t be yours. If you have a little extra cash and aren’t in a big hurry, working creatively with small batches of concrete mixed in a wheelbarrow can be downright fun! Editor's Note: You might be interested in a companion article that Dorothy wrote for our November/December 2004 Issue #90. Entitled, "Water pumping windmills," Dorothy includes an historical background of windmills, explains how they work, their uses, windmill installation and maintenance, and more. Issue #90 is sold out, but you can view the article online. Photocopies of the 8-page article are available from BHM for $4. Edited by CindyLou62, May 27 2009, 08:26 PM.
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2:41 AM Jul 11