NE Nevada Water Catchment.pdf

CONSTRUCTING A WILDLIFE WATER CATCHMENT (3600 GALLON)

USED IN NORTHEASTERN NEVADA

(January 2003 version)

The Complete Wildlife Water Catchment Tank Two 1800 gallon, low profile, heavy duty, cross-linked polyethylene catchment tanks that allow even elk or bighorns to drink directly from them, form the basis of this system. Cross-linked polyethylene is superior to fiberglass and steel in its strength-to-weight ratio. Elko Bighorns Unlimited, Boss Tanks, Nevada Division of Wildlife, and the Elko Field Office-BLM cooperated to design and produce this low maintenance, low profile, easily installed, freeze damage resistant, water catchment tank. Using this tank precludes failure from float valves or excessive plumbing and joints. The tank and cover are strong enough to withstand elk, cattle, and snow loads without collapsing, puncturing, or cracking.

The total weight of the tank and cover is about 800 pounds. The cover easily attaches and detaches, if needed, for transporting and field placement. The catchment tank can be transported, without an overload permit, on a 16 foot-long flatbed truck or trailer, but light enough to be conveyed on a pickup or by helicopter at the field location. The catchment has been designed to maximize reliability and minimize maintenance. For visual resource management considerations and other reasons, the catchment tank is low profile and dark brown in color. If needed for visual resource management considerations, it can be special ordered in other standard environmental colors. No painting is required. The color of the tank is inherent to the tank material. The water holding portion of the tank is seamless one-piece construction, eliminating leaks for reliability. The drinker and small animal ramp are molded of the same strong cross-linked polyethylene into the cover, further reducing maintenance of separate parts.

Fully Constructed Water Catchment as built in Northeastern Nevada A set of drawings and a material list of a 3600 gallon fully constructed water catchment, as they are built in northeastern Nevada, are included in the reference package. To increase reliability, very few components make up this system. It is composed of collection aprons, “Johnson” screens, external pipe couplers, “Drisco” or heavy-duty polyethylene pipes, water catchment tanks, and an optional overflow pit. The water collection aprons, the “Johnson” screens, the couplers, the “Drisco” pipe, and the tanks are sold as kits by BOSS TANKS.

Selecting a Field Site First you must select a site. An ideal site for this kind of catchment is in a location where the intended animals benefiting from the water, will use it. For example, you generally wouldn’t place a water catchment for bighorns or pronghorns in a site covered by trees; these animals are not comfortable in this kind of habitat. On the other hand, mule deer and elk would be at home in such cover. A slope (generally 3 to 20 percent) is needed for this type of catchment, so gravity will work for you. Easy digging, somewhat deep soils are always a blessing.

Backhoe Scraping the Apron Pad With a backhoe, a pad is prepared for the water collection aprons. As provided by the supplier, the unfinished size of each apron is 22.5 feet by 100 feet. For each apron, a pad of about 40 feet by 130 feet is needed to give the backhoe room to maneuver. With two aprons, a single pad of about 60 feet by 130 can be used.

Apron Being Rolled Out Each collection apron is a single piece of at least 60 mil thick, high-density, polyethylene liner, manufactured with a pipe boot sized to accept two-inch diameter poly pipe. In the past, this material as used for a collection apron required plastic welding in the field with expensive specialized tools and an experienced liner crew. With this system, no field assembly or plastic welding (and no expensive experienced crew to do the welding) of pieces is required for the apron. High-density polyethylene has advantages over other plastic liners, such as hypalon. Rabbits like to eat hypalon. They don’t seem to care for high-density polyethylene. High-density polyethylene liners exposed to the sun have now survived 30 years in field tests. The aprons are rolled out, downhill from the high side of the pad, letting gravity assist in the effort.

The picture above demonstrates in the past how the polyethylene apron material required plastic welding in the field with expensive specialized tools and an experienced liner crew

The picture on the left demonstrates how this system uses a pre-welded apron with pipe boot that does not require the equipment above to be used at the field location.

Marking the Apron Edge Once the aprons are placed where they are going to be, the ground at the edge of the aprons is marked for the top and side trenches. Gypsum or lime is spread along the liner edges to give the backhoe operator reference lines to build trenches and berms, to secure each apron. Marking paint has been tried instead of lime or gypsum, but it does not work as well in dusty conditions.

To locate where the trenches are required, trying to mark straight square lines using tape measures, strings, and flags has proven more time consuming than just rolling out the aprons and marking the edges.

As the liner comes from the manufacturer, the pipe boot is at the front or outside end of the roll.

Rolling out the apron at this time, serves another function; it allows re-rolling with gravity assist. The re-rolling places the boot end to the inside of the roll. When the final apron placement is conducted, gravity can be used again to help unroll the liner, but this time the pipe boot will be at the bottom, where it is supposed to be.

Moving the Apron(s) Out of the Way To do the re-roll, start at the uphill end and roll-up the liner while going down the hill. This re-roll does not have to be pretty. It only has to be good enough for the backhoe to transfer the apron back to the top of the apron pad and out of the way.

Digging the Top and Side Trenches and Building the Berms The top and side trenches are now dug and the berms prepared. The trenches are built with the hoe bucket digging just inside the marked lines. On the top and sides of each apron, the material from the trench is placed on the apron side. The trenches only need to be about 18 inches deep. The material placed on the apron side is packed and used to form a berm, at least 12 inches high. The side trenches are built to about ten feet above the pipe boot.

Installing the Aprons The backhoe is used to lift the aprons and move them to the top of the pad(s). In this process, each apron must be turned in the proper direction so when it is unrolled downhill, the pipe boot will be at the bottom, pointing in the air.

Rocking the Aprons After the aprons are rolled out, rocks are placed on them before the trenches are backfilled. It is particularly important to rock each apron at the base of the berm and on the berm. This prevents the backfilling operation from excessively pulling the apron material into the trench and creating air pockets beneath the apron. For now, rock the entire apron except for about the bottom twenty-five feet or no further than the extent of the side trenches.

Constructing the Bottom Berm The bottom berms are at least three feet tall. They start from the side berms about 10 feet above the level of each pipe boot. When an apron is fully installed, it should be an arrow shape with the pipe boot being the apex. Refer to your drawing in the reference package. The aprons should funnel water to the pipe boot areas. To define where the bottom trench and berm will be, fold the apron back from the bottom towards the top to where the pipe boot is located. Mark a spot on the ground at the point where the pipe boot is. Now fold the apron back another ten feet above the pipe boot. This should have the apron out of the way so that a diagonal line can be made from the end of each side trench to a point about 10 feet in front of the pipe boot mark. Both halves of the bottom trenches can now be dug staying inside the lines you just made. The trench material is used to build a berm at least three feet tall. Usually additional fill, often from what was scraped originally from the pad, is used to create the bottom berms. Until a pipe is installed through each pipe boot, temporary gaps are left in each bottom berm at each apex.

Installing the Pipe Into the Aprons Two-inch diameter, 160 PSI, SDR 11, “Drisco” or heavy duty poly pipe is used to transfer water from the collection aprons to the tanks. This very thick wall poly pipe can freeze solid without bursting. A couple of bodies get on the end of each pipe and feed it underneath the aprons through the pipe boots. Once the pipe is sticking a foot or so through a pipe boot, two or three large hose clamps are placed over the boot and tightened over the pipe.

Attaching the Coupler Because of the wall thickness of this pipe, it is almost impossible to use an internal galvanized barbed fitting to couple this pipe to anything. Instead, each pipe is fitted with an external coupler and O ring.

An external coupler makes the maximum inside diameter of the pipe available to siphon water collected, as fast as possible.

Attaching the “Johnson” Screens Next come the “Johnson” screens. This 6-inch diameter, by 2-foot long, cylindrical, stainless steel, water well screen, filters the water prior to entering each pipe. Cheaper alternatives have been tried, unsuccessfully. For maximum durability over the long-term, it is worth the expenditure to use stainless steel. A “Johnson” screen precludes small animals, such as lizards and insects, from being trapped in a sump and contaminating the water source. A 2" elbow can be put between the coupler and "Johnson" screen if needed, to make the "Johnson" screen rest in the lowest part of the apron.

Final Dress-up Around the Apron(s) The temporary gaps in the bottom berms can be backfilled. The backhoe can do the primary backfilling, but the final dressing at the apex where the Johnson screen is located will have to be done by hand. It is important that the final apex berm and the area around the Johnson screen are shaped so that the Johnson screen and the pipe lay flat and that they are in the lowest part of the apron to capture the most precipitation.

Backfilling the trenches can be finished and general smoothing of the pad(s) can be completed. As the backhoe fills the trenches, folks with shovels from on top of the apron on the berm can temporarily pin the apron against the inside of the trench as the backhoe pushes in fill. This insures that the apron is buried sufficiently in the trench.

Digging Ditches Between the Aprons and Tanks Generally, two ditches, 18 inches deep and about 150 to 200 feet long, from the aprons to the tanks are dug. This distance can vary to whatever length is needed based on the best cover or area suitable for the wildlife using the water. Just make sure the tanks are sufficiently downhill enough that water collected at the aprons, will flow into the tanks.

Tank Pad Preparation The pads for the tanks are prepared. The tanks can be buried up to 24 inches deep, which will place the drinker lip within two inches of the ground. The pads must be level. This can be accomplished using a long straight 2"X4" board with a hand level placed on top. The fastest way is with a laser level and rod, with readings being taken to tell the backhoe operator where he must cut and fill. Dress up the pad by hand and remove any loose brush or rocks. A few folks on McLeods work well. After the pad is dressed, a scrap piece of apron material is placed on top of the pad. The tanks do not have to be buried. A level pad must be made though. A raised ramp around each drinker can be built up with rocks and dirt so the lip of the drinker is no more than 20" high above the ground. This allows kids, calves, and fawns to reach the water. A consideration for burying the tank is vandalism. With the tank buried almost to the drinker lip, the water holding portion of the tank is protected by soil. Only the lid is exposed to a bullet. Bullet holes in the lid will not affect the functionality of the catchment.

Tank Placement The tanks are dropped into position on top of the scrap apron material with a backhoe, or about 12 healthy adults. The scrap apron material allows the tanks to be easily scooted around if needed.

Scooting the tank around without the scrap will create lumps in the level pad as rocks or other materials roll underneath the tank as it is moved. This then forms air pockets under the tank which compromises the footing and support for the tank.

Try to place the tanks (consider this before you start to make the pad as well) so that their drinkers face a northerly direction. In this way, the water in the drinker is subjected to much less direct sunlight, reducing the amount of evaporation that will occur.

Roll the Pipe Out The 2" poly pipe is now placed in the ditches between the catchment aprons and the tanks. Important: Snake the pipe in the ditch!

Poly pipe contracts and expands according to temperature. Over a length of a couple hundred feet, it can contract several feet in freezing weather. Snaking provides the pipe the ability to contract in freezing temperatures without pulling away from the tank or apron.

Pipe the Tanks The pipes from the catchment aprons can now be put into the tanks. Based upon the angle and location of the pipe coming to a tank, using a two and a quarter inch hole saw, cut a hole anywhere in the lid that will best work. If the hole is going into a curved surface of the lid, angle the cut into the lid at about the angle the pipe will go into the lid. Roll the pipe out long enough, including your snake in the ditch, so that the pipe will extend into the tank about 8 feet. No fittings are necessary; simply push the pipe into the tank several feet through the hole you cut. Any hole in the lid will be above the water level in the tank and drinker. Generally, about half way up on the lid, on the flat surface at the back end, is the easiest place to cut the hole. Using 160 PSI poly pipe and placing it about 8 feet into the tank precludes large animals from crushing the pipe or kicking it from a fitting.

Place the Support Columns Next, the support columns inside the tank need to be installed. A person(s) must climb into the tank through the manhole cover for this task. Short pieces of PVC pipe included with the tank are jammed into cylindrical pockets in the underside of the lid and over cylindrical protrusions on the tank bottom. This may take some force to distend the lid up enough to make room to slide the PVC pipe over the protrusion. While in the tank, take the time to sweep or clean up the filings from the hole that was cut for the pipe from the apron or any other debris that may have gotten into the tank up to this point.

Backfill Around the Tank With the backhoe and hand tools, carefully backfill around the tanks. Try to avoid placing dirt on top of the tank lids. The lids also serve as water collection surfaces. Water picking up dirt on the tank lids, can end up in the tanks. This isn’t real critical, but it is nice to try and keep the water in the tanks clean. If you plan to have an overflow pit, don’t backfill the area around the overflow fittings at this time. The ditch(es) for the snaked pipe between the tanks and aprons, can now be backfilled as well.

The tank and the pipe are tough, but still try to avoid dropping big rocks against or on them during backfilling.

Dig the Overflow Pit One inch of precipitation falling on a square foot will yield .623 gallons of water. The collection apron for one catchment tank, in its finished size, is about 85' by 15'. This 1,275 square foot surface has the capacity to collect 7,943 gallons of water in a year, with 10" of precipitation. Northeastern Nevada will receive thunderstorms, during the late summer of an inch, in a couple of hours. An oversize apron permits refilling the tank in these short, intense storms. An oversize apron allows the tanks to remain full during extended droughts. An oversize apron provides sufficient water to freshen the store regularly and discourage stagnation. A shallow pit reservoir (15 ft. diameter by 4 ft. deep) to collect most of the excess water is dug below the tanks.

An alternative to a pit reservoir is to run the overflow from the first tank downhill to a second tank as depicted in the drawing below.

This allows one apron to supply 3600 gallons of water storage. It is useful where terrain conditions limit apron construction or where higher (10 inches +) annual precipitation levels do not warrant construction of an apron for each tank.

Install Overflow Pipe A two inch diameter, 100 PSI, polyethylene overflow pipe is installed between each tank and the overflow pit. The overflow pipe runs on the outside of the tanks to the bottom of the tank lip. This precludes significant water loss from pipe joints in the body of the tank. Be sure to snake the pipe.

To make the turn in the overflow pipe from the bottom of the ditch to the overflow fitting in the lip of the tank, a plastic, barbed, 90 degree elbow fitting is used. Double clamp the fittings.

Install the Overflow Screen To prevent rodents from climbing into the pipe, the opening of each overflow pipe in the pit is covered with 1/8 inch, stainless steel screen, secured with hose clamps. A foot long piece of screen is rolled like a jelly roll and pinched off at one end. About 4 inches of the open end of the screen is slipped over the pipe. This leaves about 8 inches of screen to dispense the water coming through it.

Bentonite the Pit Four sacks of bentonite are spread and raked into the bottom of the pit. Upon wetting, this clay substance swells to seal the pit so it does not drain as rapidly. The ditch between the pit and tanks is backfilled. The sides of the pit are sloped so wildlife can easily climb in and out and use the water in the pit, if they want.

Fencing Around the Aprons A four barbed-wire fence (46" high) is built around the aprons. Starting from the ground, wire spacing is 12", 12", 12", and 10". Post spacing is 16'6" or closer, with a wire stay in between. The idea is to discourage big game species, cattle, and horses from entering the apron area. Easy Fence braces (2 triangles and 2 rectangular) are used to build each corner. Three seven-foot tee posts, pounded extra deep, are used for the corner posts to tie in the rectangular braces. Hose clamps are used to attach the braces to the posts. The fence can be placed within 6 feet of the apron. Usually, this is already in the cleared area from the initial pad preparation.

Fencing around the Tanks and Overflow Pit A two-cable fence is erected around the catchment tanks and the overflow pit. The bottom quarter inch cable is 19 inches above the ground. The top cable is 19 inches above the first cable, or 38 inches from the ground. Quarter-inch cable clamps and one-half inch eyebolts are used to attach the cables to the three-post, wooden fence corners. Two holes, 1/2 inch in diameter, are drilled through each corner post for two eyebolts. A drawing of this fence, with corner details, is included in the reference package. This fence is wildlife friendly. Big game can easily enter the tank and overflow pit area to drink. This fence is strong enough to withstand repeated use by elk. Occasionally, a bovine calf will enter the area, but this fence has been found to effectively exclude full-grown cattle and wild horses. Additional cables can always be added, if needed.

Easy Panel Cable Fence Corner An alternative to a wooden corner is to use Easy Panels (as in the barbed wire fence) and chain-link fence hardware to attach the cables. This method is slightly more expensive for materials but does not require extensive digging. It is particularly useful in rocky soils or when volunteers are the principal construction personnel. Not as much skill is required to build this kind of corner as compared to a properly constructed wooden corner. It also does not require as much equipment to be taken to the job site. Install the easy panel corners, then attach a chain link fence round band at the corner. Attach a chain link fence band adjuster bracket to the round band.

Install the eyebolt to the band adjuster bracket. The cable is fastened through eyebolt on the one end. The far end of the cable is simply wrapped around and fastened at the other fence corner to complete the initial cable hanging. Tightening the nut on the eyebolt to make the cable taunt is the final step.

Tee Posts and Let Down Clips Steel tee posts are used between the corners on about twelve-foot spacing. The cables are attached to the steel tee posts with offset slot, let-down fence clips. The fence clips are squeezed onto the tee posts with a special tool. The wooden posts, other than the corner post itself, have special offset slot clips nailed to them to hold the cables. Other kinds of metal let-down fence clips and plastic electric fence clips for tee posts would probably also work.

Pinching Close The Let Down Clip Slot Once the cables are in place and tightened, the offset slots are pinched closed. Compared to barbed wire, this new cable fence better withstands heavy winter snows.

Seeding Finally, in the fall, the disturbed areas are seeded with a native seed mix to re-vegetate, prevent erosion, and discourage weed invasion.

Any mention of trade names, commercial products, or specific company names in this document and associated reference materials does not constitute an official endorsement or recommendation by the Federal Government. BLM personnel or persons acting on behalf of the BLM are not liable for any damages (including consequential) that may occur from the use of any information contained herein, including reference materials provided. Since the technology and procedures are constantly developing and changing, the information and specifications may change accordingly.

The author acknowledges and thanks Boss Tanks, Mark Vanoni , Steve Trask, and the various offices of the Nevada Division of Wildlife, Washington Department of Fish and Wildlife, Bureau of Land Management, and Forest Service for their photographs and assistance to develop this document. His current address is: Roy Price at Salem-BLM, 1717 Fabry Road SE, Salem, OR 97306, phone (503) 375-5662 or E-Mail Roy_Price@or.blm.gov

For more information on Northeastern Nevada Wildlife Water Catchments, contact:

Ray Lister at Elko-BLM, 3900 East Idaho Street, Elko, NV 89801, phone (775) 753-0200 or E-Mail Ray_Lister@nv.blm.gov

Joe Cumming at Boss Tanks, P.O. Box 5689, Elko, NV 89802, phone (775) 738-2677