EPIC System - Frequently Asked Questions

  1. Can this system be adapted to cold climates? What about winterization, and frost heaves? Initial technical development of the EPIC design actually had its birth in Western New York, so the brutality of winter conditions have been well observed with no negative affect on the design. Water distribution is by gravity, and it is not a pressurized system where freezing water enclosed in a pipe expands and breaks the pipe simply because it has nowhere else to go. The EPIC chamber has an open bottom, and the six-inch high arch never has water content deeper than the bottom three inches. The short connection stubs made of 2" Schedule 40 PVC pipe simply transfer water from Chamber to chamber and are never full of water. Winterization is a simple act of shutting off the water supply source or flicking the switch that supplies the power to the recirculating pump. There is no need to blow out any pipes, and the system simply works as a drainage system as the plants and grass become dormant. If it's a dry winter even the residual water left in the EPIC chambers gets absorbed into the sand matrix from which it slowly evaporates from the upper level if above freezing, or sublimes if below freezing. Frost heaves do not appear to be a reality because as ice crystals form in the damp sand, there is enough void space in the matrix to accommodate the expanding ice crystals without pushing the soil mass out of shape. Additionally frozen sand remains highly porous and melts easily should winter rains become a reality after a cold spell. Liquid water has enough heat retention to melt the frozen ice crystals in the sand, and the system quickly goes to the drainage mode as the 2" connector pipes were already free and clear of ice by design. A working roof top garden on top of a Minneapolis, MN ten story building has been functioning flawlessly for now over four years - need we say more?

  2. Are there problems with root intrusion? Root growth in EPIC systems appears to be naturally limited to the 10" - 12" capillary zone. Root growth is prolific in this zone because oxygen and moisture levels are always in an ideal balance in an uncompacted sand matrix. Roots become minimal in the saturated zone because it is simply too wet with a diminished (but not anaerobic) oxygen content. Roots will hug along the exterior surface of the EPIC chamber, but are restricted naturally to enter the interior of the chamber because of the offset hole placement. In order for a root to access the interior, the root tip would first have to grow sideways through the exterior EPIC hole, then make a sudden 180-degree upward growth, and then continue upward through air or soil-less water and access the second inner hole all of which are located within the saturated zone. Physically and biologically this is not a natural event. The presence of roots around the exterior holes does not diminish but actually improves the capillary dispersal of water, the intended function of the design. In ordinary applications, EPIC beds themselves are designed to grow grass and shallow rooted shrubs and small trees. Large trees that may be part of EPIC systems in landscape projects are actually planted between EPIC liner pans so the deeper and invasive tap roots can continue to wander below and along the sides of the liner pans. Another procedure is to install individual liner pans (one per tree) 3'-4' below the surface under the tree ball thus only providing drainage and irrigation for the individualized tree. This procedure has applications for new orchards, vineyards, or tree-lined streets in urban areas where even ordinary street runoff water can be intercepted and diverted to feed the system.

  3. Have you experienced rodent damage? To date we have not noticed rodent damage in our installations including a garden bed installed over a known area of vole tunnels. Although a rodent could start to burrow from above into the damp sand, at 10" below the surface it would encounter the saturated zone with the consistency of quick sand. The tunnel would collapse, and the soaked environment would not be attractive as a habitat. Tunneling below the liners might occur in border areas of EPIC beds, but the liner may simply provide a ceiling limit for the tunnel, as there is no real incentive for a rodent to gnaw a flat plastic liner. However if a hole is somehow breached from below, the tunnel would quickly fill and self-seal with the slurry of wet sand. Because EPIC beds are modular interconnected units, severe damage (i.e. meteoroid strike) to one cell does not affect the entire field. A problem cell will demonstrate a "sink hole" condition at the point of damage and the subsequent unit will show signs of drought stress, as the water may be being short-circuited. Problem cells are easily dug up, repaired or replaced, and the same sand is reused after repair.

  4. Any damage from aeration tines? The standard yard or athletic field design calls for an overall depth of 13"-14", which still provides a 7"-8" cover of sand over the crown of the EPIC chamber before seeding or sod placement. A six inch tine would not damage the chambers, however the recommended tine length is 3"-4" such as a Ryan L28.

  5. What issues are there with western soils, salt content, salt crusting etc.? Unless natural sand is actually available on the construction site, the 13"-14"growing matrix of the EPIC bed is actually imported washed sand, where the manufacturing process has probably eliminated most of the soluble salts from the sand. See choosing the right sand flyer in the handouts. As such the nature of native soils has no relevance, as the system is isolated from their influence. We have installed two back yards in high Boron subsoil area, but since the water source for watering is different from the natural ground water below the bed, the boron has no influence on the EPIC beds. Salt concentrations in the "western" soils actually occur because dissolved minerals present in ground water formations are deposited on the surface through overhead irrigation practices. The hot climate evaporates the water but leaves the minerals (salts) behind as a white residue on the soils or films on fences and other valuable man made objects. A subsequent water application dissolves the salt again but only drives it deeper in the upper crust. The process appears visually to make the white crust disappear as the salts temporarily dissolve, but in actuality we have only added more salts with the new dose of ground water. Long periods without the natural dilution and cleansing mechanism of precipitation (essentially distilled water) cause the salt content to build up deeper and deeper from the surface until the salt concentrations become toxic in the root zone and the soils become "sterile". EPIC systems resolve the problem by several features. EPIC beds remain relatively dry at the surface due to the limitations of distance the water will travel upward through capillary action. As such most water loss from the system occurs by transpiration through the plant tissues than by actual physical evaporation, thus crust formation at the surface is greatly reduced. Plant roots can selectively isolate some minerals from absorption into the plant, thus the minerals remain in solution with the below ground water mass. Because water requirements are reduced by at least 50%, there is a proportional reduction of mineral introduction if ground water formations are used as the water source. Sand itself does not have a great affinity to bind and hold minerals on their surface, and an EPIC system is not a totally enclosed system. Every time it rains (mostly a winter season event out west) mineral content introduced by ground water is diluted, and eventually in heavy rain events flush the accumulated salts from the beds through the terminal drain exit.

  6. How about oversaturation, anaerobic conditions, and root depth? By design it is impossible to over water an EPIC bed. The saturated zone is restricted by design to the lower 3 inches. Any excess water is simply transferred to the adjoining cell or eventual drain point. Depending on choice of design, an EPIC bed can actually keep up with rain events of 23" per 24-hour periods and quickly return the field to its saturation constant. Due to the porous structure of the washed sand and inherent air pressure above it the capillary zone is always aerobic. EPIC systems never produce shallow root systems. All grasses even from seed have achieved 10" deep roots in a three-month period. The long roots provide exceptional turf adhesion as the roots spiral and anchor themselves around the sand grains. One-month-old sod is impossible to pull up by hand. Shallow root growth is a phenomenon of overhead irrigation where either compacted soils prevent root penetration, or surface water and surface nutrients initiate surface growth,- which subsequently accelerates thick thatch development,- which further restricts water penetration,- which leads to runoff and water waste.

  7. How do you handle emitter flushing or clogging? EPIC does not employ any emitters or moving parts. EPIC chamber transfer holes are one inch in diameter and we provide over 10 square inches of openings for every foot linear length of EPIC structure. The interface cannot clog and it never requires any maintenance. Mineral buildup and clogging occurs in pressurized systems that employ microscopic holes for water delivery (soaker hoses, drippers). Because the flow is intermittent in these systems, the area around the microscopic exit area experiences a wet period and then a dry period. During the dry period the water droplets evaporate leaving the minerals adhering around the microscopic hole, and constricting the pore even further by crystal formation. Eventually the microscopic hole seals up completely and the surrounding soil pressure will prevent the "plug" from clearing itself even at 100 psi pressures that may be present in the main delivery line. This phenomenon is similar even on relatively larger openings as may be found on the aerator screen of a kitchen faucet head.

  8. What is the durability of sand based surfaces? The EPIC profile though made of sand provides a strong and stable configuration for loading and resistance to settling and compaction. The damp sand profile mimics the nature of the damp area of an ocean beach - firm enough to be driven on but not as fluid as the sand below water line (quick sand) or as unstable and shifting as the dry sand in the higher dune area (blow sand). The unique stability of damp sand is achieved by the molecular adhesion of water films to the sand particles - the ability to provide structural integrity in elaborate sand castles. Durability of the surface finishes will depend on the maintained condition of meshed root growth of turf which adds to the sheer values on the surface. EPIC systems can also be reinforced with incorporated reflex mesh elements in the top layers of the sand to add additional sand stability and load bearing features. With the reflex mesh elements EPIC turf areas can be used as supplementary parking areas or "green" fire lane access roads for trucks without distortion even in wet climates. For permanent durable surfaces the EPIC profile can be used as the base for pavers, concrete patios or artificial turf.

  9. What is the dollar cost difference between EPIC and the conventional irrigation? Because EPIC combines drainage and irrigation in the same package, reduces water use significantly, and minimizes system maintenance requirements, many factors have to be entered into the comparative equation. Additionally, most of these factors are highly dependent on local weather conditions and water prices. As such costs will vary from project to project and can not be generalized. The final product is also tempered with cost of additional components that are not EPIC products. Large projects usually factor out to be less expensive with EPIC when all the factors are analyzed. Smaller retrofit projects may be more expensive short term but are usually less expensive than the alternatives when taken in a three- to five-year context.