A well-designed sustainable drainage system and water treatment plan is fundamental for the long-term health, safety and functionality of urban, suburban and agricultural communities alike. Efficient drainage and wastewater management works hand in hand with effective recycling and waste management practices.
Sustainable drainage and wastewater design are fundamental for the lasting development of agriculture and infrastructure. A well-planned system is necessary to adequately foster overall societal health, keep homes habitable and streets dry. Efficient drainage and wastewater management works hand in hand with effective recycling and waste management practices. Drainage systems capture water, reclaim it, and convey it to an appropriate offsite location to be processed and treated for waste. When water is captured, it must be adequately processed for both hazardous and non-hazardous waste before it can be outlet into a body of water or reused.
Waste materials including plastics such as HDPE, household goods and biowaste are further separated and ideally recycled. It is hard to believe that just years ago, manufacturers would dump untreated processed water into streams without giving a second thought or repercussions. These days, the idea is to both collect and convey in a conscious way. Product material choices are those that qualify for LEEDS credits. Following collection, wastewater treatment facilities implement bio and sand filters to remove impurities for water reuse or discharge. Materials such as plastics, batteries, light bulbs and other household goods that inadvertently made their way to the waterways are further separated and sent for recycling when possible.
Drainage systems can be divided into surface and subsurface elements. Surface drains are designed to remove excess runoff from the land which can accumulate and cause pooling. Subsurface drains are used when there are shallow water tables present. They can also be used in soils with a low infiltration capacity.
Surface drainage is made up of exterior ground drainage applications including trench drains and catch basins. Trench drains (https://swiftdrain.com/trench-drain-systems/) are implemented on account of their longevity and versatility of use. Materials are composed of stable thermal set polymers and alloys that are temperature resistant and will not affect the surrounding soil. Surface materials include U.V. inhibitors, which are non-reactive to prolonged sun exposure. The surface grates come in a variety of recycled alloys and polymers including stainless steel, galvanized steel, HDPE and fiberglass. Catch basins are four-sided entry points that filter incoming water with sediment baskets, filter traps and occasionally sand filtration devices. The water is collected by the trench drain and conveyed into the catch basin where it is then outlet offsite.
The function of a drainage system is to collect minor storm runoff and convey major flood runoff to an outlet or discharge point. Stormwater drainage systems are divided into two classes: minor and major. Minor systems deal with run off and major systems deal with flood.
These systems can be as simple as a 3” schedule 40 pipe, connecting to an end outlet on a trench drain or as intricate as implementing multiple trench drain runs, catch basin, pipes, pump stations, and retention and detention elements.
The objective for roadway stormwater drainage is to keep streets dry, clean and usable. To be effective, it must be designed to collect and convey runoff to a carefully chosen discharge point. This is done without over accumulating at intakes and collection areas. Sustainable drainage systems collect with building materials and drainage components qualified for LEEDS credits while minimizing the effects and impact on soil.
After water is collected, it must be treated. Wastewater treatment is divided into two phases: phase one and phase two. During phase one, wastewater is held in a detention chamber where heavier solids sink to the bottom while lighter solids float to the surface. This allows for easy separation and extraction of waste.
Phase two focuses on the degradation of waste through anerobic and aerobic biological systems. These systems include implementing bio filters and oxygen aeration methods. Sand filters extract compounds from wastewater. Oxygen aeration increases oxygen levels and makes water more suitable for reuse. This process can take days of detention and processing.
Sustainable wastewater treatment uses natural processes like photosynthesis, aeration and oxidation while leveraging renewable sources of energy like sunlight and wind. This process has a strong focus on reuse. Increased efforts have gone into reclaiming rainwater water—known as greywater—and reusing it in irrigation applications.
Greywater can be used for things like lawn care, agriculture and refilling ground water sources. A well designed and executed sustainable drainage system collects rainwater and conveys it to a wastewater treatment facility. This is achieved with minimal effect to the surrounding area by monitoring erosion levels and sedimentation occurrences.
Wastewater includes municipal and sanitary water collected from commercial, residential and industrial properties. Wastewater can be broken down into two categories: used water and sewage water. Treatment includes removing impurities such as organic solids, liquids and gases.
Sustainable wastewater management uses a multifaceted approach using engineers, public works, scientists, environmentalists and contractors. Wastewater contains organic matter and the three main nutrients for plant production: nitrogen, phosphorus and potassium. The type of treatment required depends on where the water will ultimately be conveyed. Greywater needs little to no treatment for ocean outlets. When water is intended to be reused a simple biofilter using clay can treat grey water and make it safe for inland secondary consumption. Biofilters can be used with sand filters to manage bacteria levels, nitrogen levels and oxygen levels. Biological compounds need to be removed. Nitrogen and Phosphorus levels also need to be minimized as to not affect the surrounding soil.
Treated water gets conveyed to a detention tank where it is tested for inorganic and organic compounds. These detention tanks feed into larger chambers which monitor P.H. levels and distribute the water back for household consumer reuse. If implemented correctly, the treatment and reclamation of greywater can save millions of gallons of water a year and have lasting environmental and economic impact.
A well-designed sustainable drainage system and water treatment plan is fundamental for the long-term health, safety and functionality of urban, suburban and agricultural communities alike. Water is a vital natural resource which needs to be properly conveyed, treated and reused. Waste such as plastics, household goods and bio waste must further be removed and recycled when possible. Failure to do so can cause health implications and degradation to properly functioning infrastructure. Societies are becoming more conscious of environmental impact and implementing ways to be increasingly resourceful.
Ankit Sehgal is the President and Head of Engineering at Swiftdrain Inc. (Fresno, CA), a global drainage and infrastructure products manufacturing company. He oversees all product design and development at the firm, including engineering, materials sourcing and production. For more information, visit www.swiftdrain.com.