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I plan to use this as a substitute for a sand filter system used for stormwater quality
treatment at the bottom of a dry detention basin. The first 6 inches of the basin will
be water quality with the EPIC system and a 2" outlet then the remaining pond storage
volume above the first 6" will exit the pond through a normal outlet structure to meet
detention requirements. I think it will be a good replacement for the sand filter system
because it is not as deep therefore it will cost less in this application.
Is this what you envision to be a possible use of the EPIC system?
Yes it is a great use and this practice is being adopted by “The St. Paul Ports Authority”
as they do not want anymore wet ponds because of liability issues. The EPIC™
system must be a minimum of a 15” profile or else the sand will be soggy and soft.
An analogy would be the waters edge of a sandy beach. No structural strength.
Moving up the beach you get to a much more stable section and moving up further you get into the dry sand.
I would incorporate more 2” outlets in a header to the structure if you want to sand filter
more water than what one 2” orifice allows.
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You mentioned manifolds between the EPIC chambers? What is the diameter or size of the manifolds?
Any size you want but larger pipe size tees get expensive. We use 4” and 6” PVC pipes with 4”x2” or 6”x2” tees.
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Are they sized large enough to equalize the flow of water across the system or
is each chamber fit with an orifice and acts as its own mini detention basin?
The EPIC connection pipe between chambers is always 2”.
Anything bigger will increase velocities of the flow and may cause piping or sand movement.
Each pan and chamber does act as a mini detention basin with a raised 2” outlet.
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You mentioned if it clogs you can maintain it by aerating and "picking up cores."
What does "picking up cores" mean? Replacing the grass and sand?
No, in specialized applications (golf greens or sports fields) the core
remnants can be picked up, vacuumed up or swept up.
We also use a Kor –Topmaker which can remove the top 2” of a grass surface.
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Do the subsurface outlets have to be placed at the bottom of the
EPIC system or above the bottom such that there is always water
beneath the subsurface?
No, we do not have a zero drain in civil engineering applications.
Possible in high profile sportsfield projects in wet climates where a zero drain may be desired.
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What is used to stop the sand media from being discharged through the outlet pipe(s)
from the system? A screen? Filter fabric?
No screen. No fabric. The EPIC chamber has large offset holes that prevent sand and gravel from entering the interior chamber, while allowing water contact to the profile. The 2" gravel layer covers the outside drainage hole of the chamber pipe.
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Is aeration absolutely required or is it just a recommendation?
It is a recommendation for opening up the thatch to exchange CO2 and O2 if thatch build up or
“black layer (BPL) or anaerobic activity” develops.
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You mentioned contractors experienced in EPIC system installation....are there any
in western New York State? Or is it easy enough to install such that a
representative from Rehbein need not be present during installation?
We would like to be present if a contractor has not been through our
training and wants to get certified. These systems are simple to
install but there are definitely important concepts and construction
methods to follow. We have gained much experience in installing the
EPIC™ system and the company never wants a poor installation.
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When did you receive the patent for the EPIC system?
July 13, 1999, with new improvements accepted March 29, 2007. System refinement has been going on since 1986.
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Approximately how many EPIC systems have been installed so far?
100(+) systems of varying sizes. Have any needed to be removed or replaced for any reason? One field was not maintained well and was top dressed inappropriately over time with clay as the grounds person maintaining the field wanted artificial turf. Eventually he was granted his request and artificial was laid right over the EPIC™ system. This opened up a whole new market for us. Making lemonade out of lemons. The EPIC system, as a base for artificial turf, helps cool the intense heat felt on artificial surfaces. Eventually when artificial turf needs to be replaced the client has the option to reseed the EPIC™ system and return the field into natural grass.
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Summarize how the EPIC system works.
At its simplest, the EPIC™ system integrates the first pipe specifically designed for sand. The EPIC chamber creates a non-pressurized, gravity flow path of least resistance for water to migrate through a medium washed sand profile. The EPIC system works like this: rather than allowing water to run off any type of surface--parking lots, roofs, driveways, football fields--the gravity based EPIC™ system (essentially a network of underground reservoirs) captures and filters stormwater runoff at its source and stores the water for irrigation. By using a layer of porous sand beneath the surface of the turf, the EPIC™ System draws and filters water to an underground storage area created through the combination of chambers, pans, and PVC pipes. From this, water can then be wicked up by capillary rise through the same sand to the plant roots, thus taking care of [all] irrigation needs. Therefore, while relying on zero moving parts and on an efficiency of 100%, this single product provides superior drainage, irrigation and phenomenal stormwater management benefits to a water resources industry hungry for real solutions. The EPIC™ system has truly turned stormwater management “upside-down”.
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Is all the harvested rainwater taken up by plant roots or is there an outlet to a conventional storm sewer system or holding tank?
Yes there are outlets. Optional supplemental water storage underneath or adjacent to the EPIC system can be added to harvest water for irrigation use in warmer months. Water filtered through the sand profile drains to a final outfall. Depending on your hydraulic or hydrological design you need to design in a 2” outlet or multiple 2” outlets. If too many are needed they can be manifolded together to discharge through larger drainage pipes. Largest one so far is a six inch or multiple 4” PVC pipes. Also very easy to model using HydroCAD.
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How much maintenance does an EPIC system require (besides mowing the lawn)?
Regular aeration, fertilization, overseeding, pesticides, and fungicides as awareness of landscape condition dictates. Biological growth is very prolific. Lawns grow so well that you need to keep on top of your mowing. The water is distributed directly to the roots, and the concept of subsurface fertilization becomes a reality. Regular aeration in the Spring and Fall is advisable for the air exchange through the thatch. How often does the maintenance have to be done? As often as regular scheduling demands. Golf courses mow 6-7 times per week. Homeowners mow once or twice every 1-2 weeks. The more something is taken care of, the better it will look.
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What is the approximate material cost of an EPIC system per square foot or yard?
Depending on chosen designs, EPIC material costs (less sand ,labor and site prep) are either $1.60 to $2.50 per square foot. Total costs for completed athletic fields have ranged for a 100,00 SF field you are between $6-$8/SF.
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Are there any replacement parts required?
Systems can be designed with very small recirculating pumps from your storage tanks to the high point of the system. These are usually your small 1/6 to ½ HP pumps at Home Depot If so, how much are they? Starting at about $40 to a couple hundred dollars. In some manual or drainage applications the final system may not have any moving parts that need replacement.
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The NYSDEC requires that any installed stormwater system in New York State remove at least 80% of the total suspended solids (TSS) and 40% of the total phosphorus (TP). Will the EPIC system do this? If so, do you have field or laboratory tests of the runoff samples to demonstrate this so I can submit them to an approval agency and have them accept it?
EPIC™ captures and quadruple filters sheet flow and stormwater runoff and slowly releases the excess downstream in a controlled manner. Every case is different as it is such a versatile system every application is different. In general the system will physically surface filter particle sizes that are 8 times smaller than the sand grain used. Suspended muddy water has been shown a clarity reduction from 670ntu to 82 - 100 ntu's (85-88%) in filter runs through typical profile depths of sand. Phosphorus reduction will be a function of TSS content and subsequent uptake by the growing plants in the system. Currently there is a test project at RCWD in MN. There is no data from the site yet, results will be posted.
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Where can a contractor order this system from?
We are training interested contractors to install this system. If a contractor is not pre-certified, RESI will provide supervision on every installation at the client's ultimate cost. We are the primary supplier in the world and we ship directly to the jobsite from the WI manufacturer.
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Approximately how long does the EPIC system take to install per square foot or square yard?
Depends on manpower and equipment used. Previous installations have shown a range of 4,000 SF per day for a 4-man crew, up to 20,000 SF per day for a five-man crew and specialized equipment.
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Does the soil media ever have to be dug up and replaced?
No, the sand particles do not decompose, so the sand profile does not compact and remains stable indefinitely... unless surface plugging occurs by contamination of clays or silts over time. Regular aeration maintenance and collection of cores resolves the potential clay or silt issue.
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Does the soil media only contain sand or is there some other proprietary ingredients in the media?
Bottom 2” are a #10 gravel and the rest is locally obtained concrete or mason sand. Sources are pre-tested to determine the true design profile height. Optional inoculation of oleophilic bacteria or other decomposing soil microbes can be inoculated in the profile on special biotreatment applications.
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Is the system expandable? Can more treatment area be added later?
Yes, unless it is a closed system the system will need modification.
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Is there an emergency overflow incorporated into the system in case of excessive stormwater surges?
Yes, always a recommended engineering practice.
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Approximately how much volume of stormwater per square foot (or if more applicable, how many CFS of runoff flow per square foot) can the system accommodate before it overflows?
The system can hold about 2.5 gal/ SF of a 13” profile. Each 2” orifice can convey about 0.1 CFS. Optional additional pre-filtered storage can be added under the system in the form of various structures that create a void space.
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How do I design an EPIC system? Units per sq. ft. of impervious area? Or is the design custom done by Rehbein? If so, how much do you charge for the design service?
RESI can help engineers design with the EPIC™ system. It is easily done and our modeling tool of choice (so far) is HydroCAD. EPIC™ systems are modeled as ponds with a stage vs. storage table which reflects what is happening in the soil and above the soil. Below the 2” inverts 1% porosity as it does not accept zero. Above the 2” outlet the void ratio is anywhere from 33%-47% porosity for the sand and the chambers and 100% storage above the grass or landscaped surface. We also do consulting work for local engineers at $100/hr.
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Can a representative of Rehbein be on site during installation? Yes If so, how much does this service cost?
Flights, accommodation and time shall be incorporated into the cost of the project.
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Do you have details you can send me (preferably in AutoCAD) so I can specify the EPIC system on my construction plans quickly?
Yes we have AutoCAD details which we can share when needed.
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Do you have written specifications for the EPIC system that you can send?
Yes we have a specification which we can share when needed.
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Do you have installation instructions for the EPIC system that you can send?
Yes we have a construction specification addressing all installation aspects we can share when needed.
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Do I have to incorporate the EPIC system into another treatment system such as at the bottom of a detention basin or can it detain stormwater?
It can detain stormwater but retrofitting a dry detention basin is a very important application. The St. Paul Ports Authority wants to get away from wet detention basins because of the liability issue. SPPA is putting in dry EPIC™ system detention systems where all the water is sand filtered. What's the maximum amount of stormwater it can possibly detain per square foot or per unit? Each chamber can drain approximately 0.1 CFS or what a 2” orifice can discharge. Manifolding the system is easy to increase your discharge to what you are allowed to discharge.
