Compost covers are an inexpensive but highly effective method of providing moisture control during the composting process. The covers are made from "non-woven" polypropylene fibers that create a lightweight yet highly durable blanket which sheds up to 100% of the precipitation and snow-melt off a compost windrow(s) while remaining completely permeable to oxygen, carbon dioxide, and water vapor.
The cover's water-shedding ability is accomplished through the combined action of gravity and the cohesive properties of water as it moves through the fiber matrix (thickness) of the cover. As water is absorbed into and saturates the fabric, it's "wicked" down the gravitational gradient to the cover's bottom edge.
Since the effectiveness of ComposTex depends on the ability of water to "wick" from fiber to fiber down the gravitational gradient created by a sloped surface, ComposTex is designed to protect windrows that have a "peak" with sloping sides, versus windrows with broad flat tops.
Excess moisture in a compost system not only displaces oxygen that’s essential for optimum composting, but also increases the cost of screening, bagging, and transporting the finished compost. Besides avoiding these problems and their costs, additional benefits of protecting active, curing, and finished compost with ComposTex include:
In situations where windrows could become saturated from excess rainfall and/or snowmelt which creates anaerobic conditions, ComposTex prevents those conditions and the unpleasant odors associated with them.
While we are not aware of research that would explain how ComposTex can reduce the "release" of odors even though the fabric is permeable to gases, we do have a few customers successfully using ComposTex for that purpose. Two theories regarding the ability of ComposTex to prevent the release of unpleasant odors are:
Depending on a number of factors including cloud cover, the presence of rain or snow, the frequency and duration of freeze-thaw cycles, and the amount of heat being emitted by a windrow(s), ComposTex could become saturated with water and then freeze into a solid sheet and/or stick to the windrow(s) surface when ambient temperatures drop below freezing before the covers have had a chance to dry out. Therefore, ComposTex should not be used on windrow(s) requiring frequent and/or regular access during extended periods of freezing temperatures, or the cover should be unrolled incrementally as a new windrow(s) is being constructed and the unrolled portion of the cover should not be allowed to get wet.
Although ComposTex is only about 1/16 inch thick, it does provide enough insulation that temperatures have been observed to be 10 to 15 degrees higher inside covered versus uncovered windrow(s).
Scavenging animals such as rats, mice, skunks, birds, dogs, and birds as well as flies can become problematic in composting systems, and especially when food waste is involved. The ability of a compost cover to prevent access depends both on the type of scavenging animal and how determined/hungry it is. For example, while the covers may be useful in deterring flies, skunks, and dogs, rats can more easily chew through the fabric and/or simply crawl under the bottom of cover. Similarly, birds such as crows and seagulls have been known to simply peck through the fabric.
While ComposTex can reduce the rate of moisture loss to a limited degree by protecting windrows from the drying effects of sun and wind, for a variety of reasons we do NOT recommend using ComposTex for this purpose. Besides the fact that there are more effective methods for reducing moisture loss that are described in the article “Moisture Management – The Key To Successful Composting” (LINK), even with its excellent UV-protection, the durability of ComposTex will be reduced by extended exposure to high levels of UV-light. And if the moisture-saving methods described in this article are still insufficient, we recommend using horticultural shade cloth (90 to 95% “shade”) that’s specifically designed to withstand exposure to high levels of UV-light.
While ComposTex covers are typically used continuously on STATIC-AERATED windrows (ASP), TURNED windrows do NOT need to be covered on a continuous basis, which will in-turn minimize labor costs and prolong the life of the fabric. The reason they don’t need to used continuously is that active (hot) compost windrow(s) release significant amounts of moisture through evaporation, and turning further accelerates this moisture loss, and therefore, leaving windrow(s) uncovered allows them to be rehydrated naturally by exposure to rainfall. Therefore, turned-windrows are typically only covered during periods of extreme precipitation and/or after the active phase is complete when curing and finished compost is more vulnerable to excess rainfall.
Because the covers are relatively lightweight and offer minimal wind resistance, they're relatively easy to install and secure to a windrow, even in windy conditions, and especially if they're being installed or removed by more than one person. If there’s sufficient room between windrows, a cover can be unrolled along one side of the windrow and then simply pulled over the top of the windrows. On large windrow, and/or when there’s not enough room between between windrows, the covers can also be unrolled along the top. Whatever method is used to apply a cover can simply be reversed to remove it. Handling can also be minimized by using them only when they're absolutely needed, such as during periods of heavy precipitation, and/or to protect curing and finished compost. As described below in the next FAQ, tractor-pulled compost turners can also be outfitted with a “threading frame” which eliminates the need to remove a cover before turning, and self-propelled turners can be outfitted with cover-handling devices.
For sites using tractor-pulled turners, a device known as a "threading frame" can be attached to the turner which raises and then lowers the cover as the turner is pulled through a windrow(s) - a diagram and photo of a threading frame can be seen below.
For "self-propelled" compost turners, some manufactures offer "Cover winder" attachments or "fleece-rollers" that are attached to the front and/or rear of the machine to mechanically deploy and remove the covers - a photo of a fleece-roller made by Backus can be seen below. Large self-propelled cover placement machines are also available (starting at $175,000 - source available on request).
While there's both a shiny and a rough (ie. fibrous) side of ComposTex, there's no measurable difference in terms of water shedding between these two different sides. However, putting the shiny side down will reduce the amount of compost ingredients that could stick to rough side. and also provides some additional friction (grab) between the cover and the anchors used to hold the cover down. Having the rough side facing up also provides some additional friction between the cover and whatever anchors or weights that are being used to secure it from the wind.
ComposTex does NOT come “standard” with grommets (or “eyelets”), but they can be installed for an additional cost. Typically, grommets are only needed when multiple covers will be attached together to make a larger cover. The inside diameter (ID) of our grommets is ½ inch (12.7 mm). The factory also installs a reinforced “hem” which consists of two to three layers of fabric.
Because ComposTex is permeable and thereby offers minimal wind resistance, it is relatively easy to secure to windrows. As described in the “Use and Care Instructions”, covers are typically secured by placing suitable anchors along the bottom edge of the fabric.
Depending on site and wind conditions, anchors are placed at intervals of 15 ft (5 m) to 30 ft (10 m). While sandbags are sometimes used, because they can be difficult to handle, and they easily degrade from UV-light exposure, a better option is to use 18 to 25 lb truck-tire sidewalls (also known as tire “rings”) since they provide sufficient weight to anchor the covers, have a relatively large surface area, easily stack/nest for both moving around the site in a bucket or truck bed and for storage, can be easily carried (two per hand) and thrown short distances, they don’t collect water, and they are reasonably priced. Another method to secure the covers is to install a cable or rope over the top of a windrow with weights attached at the two ends and resting on the ground.
For “long length” orders, ComposTex is available in any length and in widths of 12 ft (3.66 m), 13 ft (3.96 m) 15 ft (4.57 m), 18 ft (5.49 m), 24 ft (7.32 m), 30 ft (9.14 m), 36 ft (10.98 m), 42 ft (12.8 m), 48 ft (14.64 m), and 60 ft (18.30 m). For particularly long windrows, the factory can install grommets along the edges of the covers to allow multiple smaller covers to be attached together to make one larger cover. So, for example, instead of one 126 x 126 ft cover, one could order three covers 42 ft x 126 ft with the grommets installed every 3 ft along 42 ft edge which are then used to attach the three covers together. The advantage of this approach is that the three covers (at 217 lb each) would be a lot easier to manage than one cover 126 ft x 126 ft (at 651 lb). The maximum length for “short length” orders, which are shipped from Vermont, is 50 ft for the 12 ft wide covers and 40 ft for the 18 ft wide covers.
As shown on our Prices and Quote Request page, ComposTex is available in many different widths, and the best way to determine the proper cover width is to physically measure the “arc” of the windrow(s) (to be covered ie. the distance from the bottom of one side up and over to the bottom of the other side).
Ideally, this measurement should be taken at the specific process stage the windrow is to be covered because windrow volume, and therefore the windrow height, decreases substantially during the active composting phase. However, if taking an actual measurement isn’t possible because the compost project is only in the planning phase, one can estimate the proper cover width by multiplying the width of the windrow (at the base and measured along the ground) by a factor of 1.4 and 1.3. So, for example, a windrow 13 ft wide (at the base) would need a cover approximately 18.2 ft wide at the beginning of the process (13 ft x 1.4), and a cover 17 ft wide toward the end of the process (13 ft x 1.3). However, if covers are being purchased primarily to protect curing or finished compost, the amount of shrinkage will be minimal and therefore the arc measurement shouldn’t change substantially.
There are NO advantages for using a cover that is wider than needed, but there ARE a few disadvantages. For one thing, extra fabric lying on the ground next to the covers will tend to stay wet making the covers heavier than necessary when they need to be removed. This extra fabric will also impede water flow away from the windrows causing the compost closest to the ground to become saturated with water and thereby increasing the risk of leachate and anaerobic conditions.
If none of our standard widths will fit your compost windrow(s) exactly and it is unacceptable to allow a small portion of the bottom edge(s) to remain uncovered, there are basically two options. One option is to change the width of your windrow(s). The second option is to purchase the closest larger width and then tuck the extra fabric back under itself to keep it off the ground, or cut if off. Although ComposTex is incredibly strong and durable, it's also surprisingly easy to cut with a sharp scissors or utility knife.
It’s relatively easy to cut ComposTex with a sharp scissors or utility knife, and customers often cut longer sections into shorter sections – such as one 100 ft cover into two 50 ft long covers. And with an industrial sewing machine and polyester thread one could theoretically cut and sew covers to create any width or length needed.
While ComposTex is also available in any length, when deciding the best length to order, a site operator should consider both the weight and size of the cover when rolled up. While ComposTex only weighs .37 lb/sq yd. (197 kg/sq m) and rolls are easily moved around a site with bucket loaders, at a certain point a cover could simply become too heavy and/or bulky to be practical. For customers considering purchasing a large number of covers, we recommend purchasing one or two covers to see what size works best.
Although many compost guidance documents state that a moisture content of 45 to 55% in an active compost system is an acceptable range, as explained in his article “Moisture Management – The Key to Successful Composting”, Steven Wisbaum recommends that an active compost system should have a moisture content of between 60 and 65%.Indications that the compost ingredients are too dry include: the interior is excessively hot (ie. over 150 or 155 degrees F); the material has a light color; a sample feels dry with little to no water being squeezed out, and/or; the ingredients don't appear to be decomposing.
Conversely, indications that the compost ingredients are too wet include: water is oozing out of the bottom; the interior is giving off an objectionable/foul odor; the interior isn’t heating up and looks greasy or gooey, and; many drops of water can easily be squeezed out of a sample taken from the interior of the windrow.
An easy field test for measuring moisture content is to collect a sample from the interior of a windrow grab a handful and do a "squeeze test" - a few drops of water that can be squeezed out of the sample represents an approximate 60-70% moisture content. The procedure to measure the exact moisture content of a sample taken from inside a windrow are as follows:
The moisture content of a compost windrow that’s too wet can be reduced over time by using ComposTex during wet weather, removing ComposTex during dry weather, and then turning the windrow occasionally to incorporate the dry outside layer and expose more of the wet interior to the drying effects of the sun and wind.
ComposTex can reduce unpleasant odors in two different ways:
There’s a difference between “runoff” and “leachate” and there are environmental risks associated with both. Leachate is water that runs OUT the bottom of a saturated compost and/or feedstock windrow and therefore will contain high levels of nutrients and possibly pathogens. Runoff constitutes all the rain water and snow melt that falls on a compost site that’s NOT absorbed into the windrow(s) or the compost site pad surface PLUS any leachate. And while using ComposTex will prevent windrows from becoming saturated with excess rainfall and/or snowmelt and will therefore eliminate leachate that would be generated if the windrow(s) were not covered, the rainwater that’s shed off the windrow(s) by the covers will still become runoff. And since water moving off a compost pad after a heavy rainfall will still be in contact with the bottom edges of the compost windrow(s) and therefore will absorb some nutrients and organic matter during this contact, which means that ComposTex can’t eliminate leachate or runoff.
The expected decrease in pressure from ComposTex covering a typical aerated static windrow(s) would be 125 Pa, or 0.5 inch of water.
While ComposTex can theoretically be used as a ground cover to smother and/or prevent plant growth, a more practical and less expensive option is to use a "ground cover" fabric that is specifically designed for that application. Some reputable manufacturers of those ground cover fabrics include Lumite, Dewitt, and Fabrico.
ComposTex is made with 100% UV-protected polypropylene fibers which typically provides durability of up to 4 to 10-plus years when used primarily during wet weather/seasons. However, the Texel factory does NOT offer a durability guarantee or warranty that ComposTex will remain usable for a specific time period due to the significant differences in the way that covers are used by site operators, the amount and intensity of UV-light it will be exposed to, which is also related to the frequency, duration and seasons when it’s used.
In-fact, when ComposTex is used in locations with high UV-light intensity AND/OR is used continuously, versus just when protecting windrows during wet weather or seasons, durability can be reduced to as little as one or two years. However, if ComposTex has to be used continuously and/or in locations with high UV-light exposure, protecting it with a layer of UV-blocking "shade cloth" should extend its durability to 15 to 20-plus years.
While ComposTex is specifically designed to resist tearing when handled under normal operating conditions, there are a variety of methods that can be used to reduce the risk of tearing, including:
Tears can be repaired by sewing using polyester thread.
Since ComposTex is a fabric about 1/16” thick (1.59 mm), it can reduce heat loss which can in-turn increase internal temperatures 10 to 15 degrees F compared to an uncovered windrow.
ComposTex sheds rainfall via capillary action within the thickness of the fabric. This process is facilitated by the physical properties of surface tension and cohesion of water, as well as the gravity provided by the sloped sides of a typical compost windrow. Once the fabric becomes saturated during a rainfall event, the excess water moves down the gravitational gradient to the cover’s bottom edge where it finally has no where else to go but to drop out onto the ground. Since the volume or water movement is directly proportional to the thickness of the fabric, during extreme rainfall events this water movement might be too slow resulting in some water dripping through the fabric into the underlying compost. Because of this limitation, we suggest that customers conduct pilot tests during a variety of rainfall conditions to determine if ComposTex will perform as needed. And if it is determined that ComposTex does not provide the protection needed, a site could choose to double-up the covers during the seasons when such extreme rainfall events are likely to occur.
ComposTex is a "macro-porous" cover containing one layer of needle-punched, UV-protected, polypropylene fabric. Unlike micro-porous covers, the "pore" spaces between the fibers of the ComposTex fabric are large enough that gases (e.g. O2 and CO2) can easily pass through.
Conversely, micro-porous compost covers such as the GORE cover are multi-layer laminate covers that are used EXCLUSIVELY to achieve odor control and MUST be used in combination WITH POSITIVE FORCED AERATION. Mico-porous covers are typically much more expensive than ComposTex, and in the case of the GORE cover, are commonly sold as part of a multi-million dollar turn-key system that may include stringent contractual restrictions on the use of other technologies/equipment at the facility. For this reason, CV Compost has partnered with the manufacturer of another micro-porous, multi-laminate compost cover that can be purchased with OR withOUT any other aeration system components or equipment.
There is no minimum order size to ship covers overseas but due to administrative costs and economies of scale, the shipping cost per roll decreases as the quantity increases. Overseas shipping is done either as a “partial” or “full” shipping container load but in either case the freight cost will be depend on: the number of covers ordered; the size (width and length) of these covers, which determines the diameter of each roll; the distance from our factory in Canada, and; whether the covers can be shipped as a partial or full container load. In addition, because the covers are always shipped in a roll (ie. long round package) that’s 12 ft (3.66 m) long, a 20 ft container will only be able to fit one group of 12 foot long rolls which leaves an extra 8 feet of unused space, while a 40 ft container will allow three groups of 12 ft long rolls placed end to end (36 ft total), which leaves only 4 feet of unused space. Therefore, the freight cost per cover decreases substantially more if enough covers are ordered to fill a 40 ft container.
The specific number of covers that can fit into a 20 or 40 ft container will depend on the diameter of each roll which in-turn will depend on the width and length of the covers. For example, the diameter of a 12 ft (3.66 m) wide x 164 ft (50 m) long cover will be approximately 14.7 in (37.3 cm). Since shipping containers are typically 90 inches wide and 92 inches tall, a 20 ft container should be able to fit thirty six 12 ft wide covers (6 covers wide x 6 covers deep) while a 40 ft container would fit three times that amount, or 108 covers (3 lengths of 12 ft long covers at 6 covers wide x 6 covers deep). For comparison, a cover 18 ft (5.49 m) x 164 ft (50 m) would have a diameter of approximately 21.3 in (54 cm ), so a 20 ft container could only fit 16 cover (4 covers wide x 4 covers deep), while a 40 ft container could again fit three times that number, or 48 covers. As needed, we can also ship covers via Air Freight but this method is considerably more expensive.
We have many hundreds of customers using ComposTex throughout North America and overseas. A number of these are listed on our website, and we can provide additional contacts/referrals upon request.
All orders are custom made, and production time is generally is 2 to 4 weeks. Transit time will depend on the final destination AND how the order is being shipped (e.g. Postal service, common carrier, air freight, or sea freight). Transit time for North American destinations are typically two to ten business days while the transit time for sea freight shipments of cargo containers are generally 30 to 35 days.
When the fabric degrades to the point that it starts to lose its structural integrity, one option is to repurpose the covers as a geotextile fabric laid down double or triple thickness under new roads or compost pads. Otherwise, they should be disposed in a landfill.