Some of your Questions:
Q. When is RPE not an appropriate liner choice?
Many liners, including our reinforced polyethylenes (RPE), would not be the most appropriate choice for certain applications. These might include situations where the liner would be exposed to the sun most or all of the time and still be expected to last 20 years or more. Our 36 mil or 45 mil polypropylene, with its outstanding UV resistance, would normally be the choice in this case. Another situation in which RPE would not be appropriate would be for primary containment of fuels and other hydrocarbons. In this instance, Xr-5 or a urethane liner would be suitable. The chemical composition of the material to be contained must always be considered. The LDPE/HDPE which composes our reinforced polyethylene liners has a wide range of chemical resistance. Please consult a chemical resistance chart for specifics.
Q. What is the primary difference of BTL™ vs. PPL™?
With the exception of our BTL™-40 (a double-scrim reinforced polyethylene), BTL™ liners are single-scrim reinforced and the PPL™ liners are multi-scrim reinforced.
Q. Are the RPE (reinforced polyethylene) liners fish and plant safe?
All of our BTL and PPL liners (as well as our PP reinforced polypropylene liners) are fish and plant safe. One of the main purposes for our BTL and Polyethylene Liners is to allow a safe containment environment for fish and plants to survive, so these liners were engineered to function as such.
Q. What are the most common problems associated with pond liners?
Compared to other common liner products on the market, such as PVC or EPDM (which can be prone to seam failures, punctures, UV degradation problems, etc.), BTL and PPL liners have had very few problems. If there is an issue with a BTL liner, the source of the failure or problem is identified and a determination is made regarding fault. If the failure is a warranty issue, the liner will be repaired per the warranty. Our pond liner warranties range up to 25 years.
Q. How are the pond liners tested for watertightness?
Well, the proof is in the pudding. Usually the pond is just filled and observed to see if it is holding water. Close to 100% of the time it will be fine when properly installed. Very rarely there will be a problem. Humans being what they are however, everyone makes mistakes. They are usually not a big problem to figure out, and are normally traced back to a minor inattention to detail around a pipe boot or something of that nature.
Q. What kind of manpower is required for installation?
The simple answer is "the more the better". Actually, there are several things to consider. The most obvious factor is the size of the panels. Our BTL crew regularly installs ten to fifteen thousand square foot panels manually, with 6 or fewer workers. When the panel sizes are 20,000 SF and larger, it is typical to use a beam and spreader bar to lift the roll with a backhoe or other equipment to unroll it. For these large jobs, it is appropriate to have 8 to 10 or more laborers to spread the liner. Once the panels are in position, one or two technicians will complete the field welding.
Q. Can BTL and PPL liners be joined to other types of liners? To structures?
Generally, dissimilar materials cannot be successfully heat welded or glued together, although they can sometimes be taped together or mechanically fastened together. The liner must be mechanically fastened to structures made of wood, concrete, metal, etc.
Q. What alternatives are there to welding on pipe boots, repairing holes, etc.?
Heat welding using a hot-air or hot-wedge welder is always to be used when possible. Taping is a second choice alternative when welding is impossible or impractical. As far as pipe penetrations through the liner, there are also various mechanical alternatives available, such as tank adapters (bulkhead fittings) or tape-on boot kits offered by BTL.
Q. Can heavy equipment/vehicles be driven on the liner?
It is always recommended that heavy equipment/vehicles not be driven directly on the installed liner when avoidable. However, it can be done under certain conditions. Typically, if the sub-grade is rock free and the equipment/vehicle is driven carefully and slowly without making any sharp turns, there is not a problem. A common practice is to have minimal air pressure in the tires. In cases where the entire liner is to be covered with clean fill, a "road" at least one foot deep can be built ahead of the equipment operator who continually extends the road out ahead of him until the area to be covered is finished. We have some photos of operators doing this. The key is to dump and level, not just push from one end, as this may cause the liner to "roll" underneath and can cause tension on the liner.
Q. Under what conditions should a liner not be installed?
Other than when the subgrade is obviously not acceptable, a liner should ideally be installed when the conditions are optimal. These include calm, windless conditions with no form of precipitation anticipated to adversely affect the weld quality. Open liners make great "sails" in high winds, and you could find yourself in a position of not being able to hold the liner down in a heavy wind. The rule of thumb is to always get the liner in and secure as quickly as possible. Temperature is not a big factor (other than personal comfort). As mentioned earlier, the conditions are rarely "perfect" in reality, but a liner should not be unrolled for installation if the wind is or will be excessive during deployment, or if rain or snow is present or expected.
Q. Can the pond have water in it when installing the liner? How much?
It is always desirable to install a liner in a dry pond. In the real world, that doesn't always happen. Yes, we have installed many liners in ponds holding varying amounts of water. Generally speaking, it is not a big deal to span a liner over an area with up to a foot of standing water and leave enough slack in the liner to settle into the water when the pond is filled. A bigger issue is having standing water in an area where you need to do welding. One can get pretty creative in avoiding this situation! When possible, try to position liner panels so this does not occur. If absolutely unavoidable, you will need to elevate the portion of liner to be welded so that it is dry. The liner should be as dry as possible when welding in order to achieve a proper weld.
Q. Should field seams be wedge-welded or hand-welded (hot-air gun)?
The preferred method for welding long "straight" seams is the hot-wedge welder, with the hand-held hot-air welder reserved for detail work such as boot installation, patching, small "cut up" welding, etc. When done properly, the end result of either method is just fine.
Q. When is the use of tape appropriate?
Basically, heat welding is ALWAYS the preferred method of joining liner materials together. When this is impossible or impractical, the only other acceptable method is a very aggressive single-sided and/or double-sided tape, such as TapeCoat brand tapes, which we carry. If done CORRECTLY, this has proven to be an acceptable method. Again, heat welding should always be used when possible.
Q. What tools are required for field welding?
With field welding, the liners are welded together using heat and pressure. You don't need glue, solvent, tape or anything else if you have a hot-air gun or hot-wedge welder and know how to use it. Aside from the actual welding, additional equipment normally needed includes a generator (suggested minimum 5kw), power cords (suggested minimum 12 gauge, up to 100 feet long), and equipment to facilitate deployment of larger liner rolls such as beam, spreader bar, backhoe, sandbags, etc.
Q.When is a pond too steep/shallow?
We can and have successfully lined anything and everything in the past. There is no technical reason why the shallowest pond or one with vertical sidewalls cannot be lined. Clearly, when the sidewalls are at or near vertical, the liner must be very securely anchored to prevent the potential of the liner sluffing down the sidewalls.
Q. What is the preferred method for anchoring the edges of the liner?
Most common by far is the "anchor trench", typically around 1 foot wide by 1 foot deep, or larger if desired. The most common variation on the anchor trench is the "anchor shelf or bench". Rather than going down into the ground, the shelf is a flat horizontal (or slightly canted back) area about 4 feet wide that the liner is laid onto, then buried. This method is more popular as the size of the pond gets larger. It also tends to be a little more "forgiving" when attempting to grow grass right down to the waters edge. Either method is perfectly acceptable and commonly used. More detailed drawings are available on request.
Q. How are pond liner sizes determined?
Accurate liner estimating is the proverbial "art and science". Like a lot of things, the more you do it, the better you get! Generally speaking, it is important to keep in mind that you are dealing with rectangular panel shapes. Obviously, most ponds and pits are not rectangular, so usually there will be some degree of waste involved. There are various ways to reasonably minimize this waste, which everyone appreciates. Another big factor to consider is whether or not the installer is capable of cutting off and then reattaching corners, joining rectangles together into an "L" shape, etc. These factors will help minimize waste. If this is not an option, basically one must just get a rectangle large enough to cover everything that needs to be covered and cut off the excess. Again, the more the pond shape varies from a rectangle, the greater the percentage of waste. Becoming skilled with a hot-air or hot-wedge welder is a HUGE plus.
Q. When is the use of a geotextile under/overlayment appropriate?
Requirement of a geotextile underlayment (under the liner) with our BTL and PPL liners is relatively rare. It is always a judgment call, but we don't require the underlayment unless it is impossible or impractical (cost ineffective) to achieve an acceptable subgrade any other way. The "other way" is usually to haul in and spread clean fill over the entire area to be lined. Often it is cheaper and faster to place an underlayment over angular rock subgrades than the "other way". Underlayment is also sometimes used as a means to allow the escape of gasses, such as methane, so it is not trapped under the liner. Use of the geotextile as an overlayment (over the liner) is normally to achieve a separation between the liner and any type of fill, rock, gravel, rip-rap, etc., that is to be placed on top of the liner for various reasons. As an option, we often sell a "ribbon" of geotextile overlayment (typically 8 oz. per square yard non-woven needle-punched polypropylene, whew!), usually simply referred to as "geo", which is installed over the liner on the upper perimeter and keyed into the anchor trench or shelf along with the liner itself. This "ribbon" is normally the roll width of either 12.5 or 15 feet. Prior to filling a pond, some minimal amount of fill must be placed over the entire ribbon so that it is not prone to floating. Use of this "ribbon" is an option and not mandatory. However, it is becoming increasingly popular for a number of reasons. We know from experience that any form of physical damage (from deer, kids with rocks, mechanical equipment, UV degradation, etc.) is by far most likely to occur on the upper edges of the pond liner, not out in the depths of the pond. Also, an added degree of safety is introduced with this option. The upper edges are made less slippery so kids, dogs, deer, etc. can get out more easily. So while not "necessary", this option is a relatively cheap form of "insurance" in a number of ways.
Q. What is the average square footage of liner that can be installed per day?
The answer to this question is dependent on quite a few factors, such as complexity of the job, weather conditions, number of people on the installation crew, etc. BTL has installed over 400,000 SF in a day before. Over 200,000 SF is not at all unusual. Typically, to install this much liner per day, a crew of 16 to 20 is present, along with one or more backhoes and other equipment.
Q. How are the liners rolled out on the jobsite?
The liner roll will be marked (typically on the roll itself and on the exterior wrapper) with the length, width and directional arrows. Of course, step one is to unroll in the direction indicated by the first number and arrow. The second number shown is the unfolding direction. In theory, a liner can then be placed on any of the four "corners" outside of the excavation, and unrolled in the appropriate direction. Which corner to start on is influenced by wind direction, obstructions present, available room to unroll the liner, etc.
Q. What is standard packaging for BTL and PPL liners?
BTL™24 and PPL™24 liners up to approx. 1300 SF can be shipped in a box via UPS. Liners that are larger than 1300 SF must be shipped via common carrier, such as Old Dominion, USF, Oak Harbor, etc. In this case, the liners are "accordion stacked" into a 6 foot wide pile, the pile is tightly rolled up and placed on an appropriate pallet after wrapping it in a geotextile protective layer. It is then thoroughly secured to the pallet for shipment.
Q. What is typical lead time required for fabrication of liners?
BTL has always made an effort to ship all orders as quickly as humanly possible. Normally, liners will ship within 24 to 48 hours of a confirmed order, and very often the same day. There are exceptions of course, but over 90% of the time the above will be true.
Q. How big can factory-panels be made? What are the size restrictions?
Currently, we can fabricate individual panels of our most popular 24 mil or 30 mil liners up to approx. 65,000 to 70,000 SF. A 65,000 SF panel of BTL™-24 weighs a little under 6000 pounds, so moving it around is another consideration. Our BTL™-12 liners can be manufactured up to 150,000 SF in one piece!
Q. What are the price ranges for competitor’s materials (PVC, EPDM, HDPE, PP, Urethanes, etc.)?
Selling prices for the above mentioned products can vary considerably, depending on quantity purchased, whether the liner is installed or not, who you are purchasing from, etc. Generally speaking, non-reinforced PVC is the cheapest. It is also the weakest by far, has very poor UV resistance, and like all products which are glued together, has seams prone to leaking if they are not glued correctly. It is also heavier (like all non-reinforced liners, which must be thicker in order to achieve any reasonable strength). HDPE (30 or 40 mil) is generally the next cheapest. Again, even though thicker and heavier than our RPE liners, it is a "bear" to work with. HDPE comes to the jobsite on large (23 foot long) rolls weighing thousands of pounds, must be welded entirely on-site, and is less flexible than BTL or PPL liners. EPDM rubber, typically 45 mils thick, always costs more, and the price can vary wildly. We have seen it sold for as little as $.40 per SF to over $1 per SF. It is also typically glued or taped together, and weighs 3 times as much as BTL™-24! PP (reinforced polypropylene) is in the same price range as the EPDM, but is a much superior product. We carry 36mil, and 45mil PP. It is known to have the best UV resistance available, and is one of the most flexible reinforced liners. Urethane is the most expensive liner we carry, and is for specialty applications such as primary containment of fuel. It sells for well over $1 per SF.
Q. What products can be contained with BTL™ or PPL™ liners?
Because of the inherent chemical and hydrocarbon resistance qualities of polyethylene, many substances can be primarily or secondarily contained by it, including but not limited to water, contaminated soil, oil, gas, sewage, various chemicals, etc. Long-term storage (primary) would include water and contaminated soil. Shorter-term storage (secondary) would include gas, oil, chemicals, etc. As with any secondary containment liner, a leak or spill should be cleaned up ASAP.
Q. What makes BTL™ and PPL™ liners better than other liners?
BTL™ and PPL™ are much stronger (much better puncture and tear strength), lighter weight (=larger factory panels), excellent UV resistance (exposure to sunlight) and less expensive than most of the competition. In fact, the BTL™-40's 1200+ PSI puncture strength is the highest we are aware of for any product even remotely close to the price range of these products! One of the important aspects of these liners is the fact that the need for underlayments has been virtually eliminated in most applications. Unlike the much weaker PVC and EPDM, the extremely high puncture resistance of our liner means that they don’t require a geotextile underlayment when placed over raked dirt, even if it has rounded rock in it. Puncture of the liners from underneath is virtually unheard of. The other liners are supposed to go over extremely smooth surfaces, and some require that a soil cover be placed over the liner to protect it from damage. Overall, our BTL™ and PPL™ liners are some of the most versatile liners on the market and “The Most Bang For Your Buck!”.
Q. What is PPL™-24?
PPL™-24 is a 24 mil (24 thousandths of an inch) thick Reinforced Polyethylene (RPE). It is a "5 layer" construction consisting of 3 layers of LDPE (Low Density Polyethylene) coatings sandwiching 2 layers of HDPE (High Density Polyethylene) reinforcing scrim. This method of construction results in an incredibly puncture and tear resistant lightweight liner material. BTL is the nation's sole source for this product. PPL™-24 was originated, developed and popularized by BTL, beginning in the 1980's.