True storm water management

involves a change in design

philosophy and methods

BMP T EC HNOLOG YBMP TECHNOLOGY

24 • S T O R M W A T E R S O L U T I O N S • M A R C H / A P R I L 2 0 0 7

Jonas Sipaila & William McCully

WWW.ESTORMWATER.COM

Figure 1: Clean precipitation already muddied and dirty by the time it hits the curb and gutter.

Figure 3: Plugged piping leads to system failures and overtopping.

Figure 2: Particulates moving toward inlets.

S T O R M W A T E R S O L U T I O N S • M A R C H / A P R I L 2 0 0 7 • 25

Meeting the current national, lo-cal, city and watershed rules and regulations poses the

greatest challenge in storm water management practices. Civil and wa-ter resources engineers must address widely varied problems, including rate control, water quality, water conserva-tion and fl ood protection. However, in spite of the extremely different issues, current best management practices (BMPs) typically focus on one narrow, specifi c problem; these BMPs lack the versatility to address diverse storm water challenges.

At the same time, present-day BMPs face obstacles raised by the centuries-old philosophy and historical model for storm water management that treats storm water as a waste product. This waste product model has resulted in the physical establishment of “slope” and runoff and the simultaneous con-struction of curb and gutter, catch basins, manholes, pipes and convey-ance systems that exist solely for mov-ing storm water quickly and effi ciently to its fi nal dumping ground. Therefore, a storm water movement, rather than management, system exists.

Problematic paradigmProblematic paradigm

Unfortunately, this movement para-digm has created its own problems. For example, water in motion increas-es its kinetic energy, translating into a growing erosive force that not only moves sediments, pollutants and trash material from initial surfaces, but also creates destructive downhill power.

Figure 1 illustrates the curb-and-gutter standard: The sloped surfaces of the house, driveway, road and land-scaping all lead to the manhole/catch basin structures in the road. Crys-tal-clear water that fell as a light rain event quickly turns brown in color as road rinseate and landscape erosion pick up particulates in motion (see Figure 2).

Particulates and debris moving to-ward the catch basin initially enter the below-ground pipe, then start restricting

the catch basin openings, momentarily reducing the open area. Diversionary devices merely stage the pollutants for entry during subsequent higher-fl ow events or, through bi-pass, move the water mass with increasing energy to a lower collection device. However, plugged piping or volume miscalcula-tions ultimately lead to system collapse and failure (see Figure 3).

The answer to storm water man-agement does not include creating bigger and more expensive storm water management systems. Rather, it means changing our philosophy and methods to implement true wa-ter management systems that actu-ally prevent and treat storm water pollutants.

Before pollution issues arose as signifi cant, the curb-and-gutter sys-tems served as convenient conduits to clean the immediate environment. Routinely hosing down driveways and walkways, fl ushing street traffi c ac-cident spills and debris to the nearest

catch basins, spraying streets with street washing equipment and allow-ing rain to clear away waste seemed inconsequential. However, the process of cleaning the immediate environ-ment simply transferred pollutants to larger bodies of water; it also assumed that environmental responsibility was irrelevant.

As population densities increased, so did impermeable surfaces. While engineering reconstruction kept up with water movement strate-gies, water pollutant dumping over-whelmed natural cleaning cycles, and pollution issues rose to the forefront.

Evolving BMPsEvolving BMPs

Current BMPs have evolved toward crafting devises that fi lter and capture fl oating debris or gross visible pollut-ants. These devices include catch ba-sin inserts, traps, fi lters, vortex cyclone fl ow devices, in-line diversion screens, manhole baffl es, and capture screens and fl oating barriers at fi nal discharge points. Even though gross pollutants account for the largest volume of con-taminants from storm events, this pol-lutant category actually has the least amount of biological impact on the fi nal receiving bodies of water. In general, the devices work as effi cient debris removers in light storm water fl ows, but larger fl ows overwhelm them and they have to rely on the built-in bi-pass features.

These BMPs provide add-on im-provements to existing curb-and-gut-ter systems, but they clearly fail to at-tempt to address, much less change, the foundational philosophy of such systems. Another problem involves the necessity of a higher maintenance cleaning and servicing schedule for these sorts of devices. Finally, though the eventual collection and disposal of these wastes improve aesthetics, these devices do little to prevent the infl ow of phosphates or nitrates to ponds, streams, wetlands and lakes.

Storm water detention and

“PRESENT-DAY BMPS FACE OBSTACLES RAISED BY THE CENTURIES-OLD

PHILOSOPHY AND HISTORICAL MODEL FOR

STORM WATER MANAGEAMENT THAT TREATS STORM WATER AS A WASTE PRODUCT.”

26 • S T O R M W A T E R S O L U T I O N S • M A R C H / A P R I L 2 0 0 7 WWW.ESTORMWATER.COM

retention structures in the form of National Urban Runoff Pro-gram (NURP) basins became a BMP standard to address the collection of sediment pollutants, the primary source of soil phosphates. In theory, slowing down incoming water to man-made ponds would allow some of the particulate matter to settle at the pond bottom, letting only slower and less contami-nated surface fl ows continue to the major receiving waters. Surface debris could be skimmed off while the soil sediments settle (see fi gures 4 and 5).

While this BMP has become, mostly by regulation, a cur-rent state-of-the-art requirement for storm water mitigation, by

Figure 6: EPIC System components—pan and chambers.

nature the model creates a long list of spinoff problems; in-deed, it is questionable that this BMP actually adds to the environmental equation of improving the terminal receiving bodies of water. Numerous problems with basins have been documented, but some in particular are worth noting: The basins are expensive to build and to maintain; they hog real estate; they stir up material during construction; they pose li-ability hazards; they are aesthetically unappealing; they create a mosquito-breeding habitat; they attract nuisance geese; they provide minimal recharge to groundwater; and they promote the re-suspension of pollutants.

If the ecological goal in storm water management is the reduction of pollutants that initiate algae blooms and conse-quential oxygen deprivation in the primary recipient bodies of water, then the focus in storm water management must be the reduction of nitrates and phosphate sources. Unfortunately, BMPs that tend to augment conventional curb-and-gutter wa-ter movement systems cannot mitigate the reduction of these contaminants and, in some cases, actually contribute to the increase of these contaminants.

Understanding

contaminants

Before we can advance true storm water management and treatment BMP systems, we must understand the nature of these two main storm water contaminants.

Nitrates. Nitrates (NO3¯) are the negative anions of a broad spectrum of basic chemical compounds commonly identifi ed as sodium nitrate, ammonium nitrate, potassium nitrate, calcium nitrate, nitric acid, etc. Most nitrate compounds are soluble in water and therefore will travel anywhere that water goes. Hold-ing a negative charge, they can travel great distances in soil, which by nature also carries a net negative charge. So, they can relocate to groundwater formations or larger bodies of wa-ter great distances away from the original point. Once formed, no non-biological chemical reaction in soil can precipitate or neutralize the compound. Nitrate movement and biological

Figures 4 & 5: Fenced-in NURP ponds.

absorption become part of the planet’s nitrogen cycle. Nitrate production is ubiquitous in storm water runoff

because of excessive fertilizer application leaching, for-mation in rain from thunderstorm events and washings of surfaces exposed to automobile exhaust. Because ni-trates are so highly soluble and negatively charged, an effort to control nitrate pollution by conventional curb-and-gutter systems cannot happen; water movement itself must actually be controlled.

Phosphates. The primary source of this group of nutrients is a natural rock mineral called phosphorite. It consists largely of calcium phosphate and is used as a raw material for the subsequent manufacture of phos-phate fertilizers, phosphoric acid, phosphorus and animal feeds. While commercial grade deposits can be found in Florida; North Carolina; Tennessee; California; Wyoming; Montana; Utah; Idaho; Northern Africa; and Russia, some level of phosphate is universally present in all soils of agri-cultural quality (soils with the ability to grow plants wheth-er they are weeds, turf or commercial crops).

The planet’s soils can be categorized as a percentage and combination of three particle size primary compo-nents: sand, silt and clay. All three particle components

S T O R M W A T E R S O L U T I O N S • M A R C H / A P R I L 2 0 0 7 • 27

Figure 7: EPDM liner and water harvesting.

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Article LibraryThese are editor’s choice articles from the Storm Water Solutions, Roads & Bridges and Water & Wastes Digest magazine archives, bringing you our best features related to storm water issues.

Storm Water SpotlightAn online showcase of products relevant to storm water, complete with photos and product descriptions.

Related Products and Suppliers An online buyers guide focused exclusively on storm water-related products, services and suppliers.

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are derived from weathered rock and re-fl ect the chemical characteristics of the many rock composition minerals, includ-ing the phosphorus-bearing molecules. Phosphorus molecules, unlike the nega-tively charged nitrate molecules, have a net positive charge and as such bind themselves quickly to the negatively charged soil particles. While nitrates readily move with water as compounds in solution, phosphates generally only move as “riders” on soil particles.

Sands (0.05 to 2 mm) by nature are larger particles and are primarily com-posed of quartz crystals. Therefore, there is less surface area or physical af-fi nity for phosphates to attach as com-pared with the larger surface area and negative charges available on silt (0.002 to 0.05 mm) and clay (< 0.002 mm) par-ticles. Effective BMPs for phosphate pol-lution control must integrate three source areas as phosphate control equates to the control of erosion and relocation of soil particles:1) Prevention of soil erosion;2) Sedimentation and removal of settle-

able solids formed as sands and silts; and

3) Prevention of movement of suspend-ed solids in the form of clay particu-lates, generally known as “muddy” or “turbid” water.

Some current BMPs can effectively settle sands and silts but cannot handle brown muddy water where the majority of phosphates reside. Specialized high-volume, pump-activated mechanical fi lters can make an attempt on “muddy water” in limited volumes, but high oper-ating expense, frequent breakdown and service needs make these systems not a viable solution to storm water pollution problems.

Silver bullet BMP?

True storm water management in-volves a change in design philosophy and methods. Who wants to cause a paradigm shift within the storm water in-dustry? Is there a silver bullet BMP that can apply to all or most site designs?

Imagine a BMP that:

• Effectively prevents passage of sedi-ments and thus phosphates from moving downstream;

• Allows for effective biological ab-sorption, de-nitrifi cation and use of nitrates;

• Allows for effective storm water vol-ume reduction by allowing infi ltration to recharge the groundwater;

• Prevents infi ltration in areas where it is undesirable due to soil contamination;

• Changes the way storm water is treated, used and reused;

• Filters, treats, stores and uses storm water as a valuable resource rather than a byproduct necessary to deal with as quickly as possible;

• Uses a simple design, therefore elimi-nating complicated maintenance;

• Allows the uptake of dissolved nutri-ents and other organic chemicals;

• Harvests storm water for irrigating landscaping and lawns, thus requiring 50 to 85% less water for irrigation;

• Becomes modular in form and works as a lineal BMP along county roads and highways;

• Cools and reduces the temperature of storm water runoff;

• Provides water quality treatment to the fi rst fl ush and larger storm events

with the possibility of having no out fl ow; and

• Accommodates a retrofi t conversion of a wet to a dry detention pond with under drain system.

Until now, these benefi ts have ap-peared as only a lofty goal for one BMP. One versatile BMP, however, the EPIC System, has taken this new approach to storm water management (see Figure 6).

The system is based on a combina-tion of the oldest of technology, a sand fi ltration system, and a patented and proprietary device that controls subsur-face water fl ow. The system is an under-ground irrigation, drainage, storm water harvesting and storage management system. It captures and stores storm wa-ter as soon as it fl ows over the the sys-tem. The system can turn green space, shoulders, side slopes and ditch slopes into a storm water management system. It captures and quadruple fi lters sheet fl ow and storm water runoff and slowly releases the excess downstream in a controlled manner (see fi gures 8 and 9).

System & philosophy

In 1985, Jonas Sipaila, now of Reh-bein Environmental Solutions, Inc., craft-ed the basic idea of the system. While visiting a construction site one day after a rain storm, Sipaila noticed a large pile of sand wicking up water from an adja-cent puddle. This led to a 14-year study and refi nement of Jonas’ innovative idea: to utilize a proven, reliable medi-um—sand—therefore taking advantage of fi rst-century physics to solve 21st-cen-tury problems associated with irrigation and drainage. By combining the con-cepts of subsurface irrigation, subsurface drainage and the capillary movement of water through sand from nearby water sources, Sipaila invented and received a patent in 1999 for the fi rst pipe designed specifi cally for contact with sand. Other subsurface systems have always had problems with clogging, thus hampering their effectiveness, but Jonas’ invention has eradicated those problems.

Essentially, the system is a

“SOME CURRENT BMPS CAN

EFFECTIVELY SETTLE SANDS AND SILTS BUT

CANNOT HANDLE BROWN MUDDY WATER

WHERE THE MAJORITY OF PHOSPHATES

RESIDE.”

S T O R M W A T E R S O L U T I O N S • M A R C H / A P R I L 2 0 0 7 • 29

passive subsurface irrigation and drain-age system that uses capillary physics and gravity to deliver water and nutrients to plants and to move water through an interconnected series of chambers and pans. The low pressure and greatly re-duced water volume means less energy is needed to move the water.

A simple explanation of how the sys-tem works: Rather than allowing water to run off any type of surface—parking lots, roofs, driveways, football fi elds—the gravity-based system (essentially a network of underground reservoirs) captures and fi lters storm water runoff at its source and stores the water for irrigation.

By using a layer of porous sand be-neath the surface of the turf, the system draws and fi lters water to an under-ground storage area created through the combination of chambers, pans and PVC pipes. From this, water can then be wicked up through the same sand to the plant roots, thus taking care of all irriga-tion needs.

Therefore, while relying on zero mov-ing parts and on an effi ciency of 100%, this single product provides superior drainage, irrigation and storm water man-agement benefi ts to a water resources industry hungry for real solutions. SWSSWS

Jonas Sipaila is director of innovation and

William McCully is director of engineering for

Rehbein Environmental Solutions, Inc. Joy

Misselt provided copy editing services for this

article. Sipaila and McCully can be reached at

763/784-0614.

For more information, write in 5003 on this issue’s Reader Service Card.

Figure 9: Finished Linear EPIC BMP application along impervious surfaces.

Figure 8: Linear EPIC BMP application along impervious surfaces.

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