Cisterns for Stormwater Reuse and Runoff Reduction
Low Impact Development strives to eliminate runoff by promoting infiltrating wherever practical. If your site has high groundwater, soils with low permeability, bedrock, or other limiting conditions, infiltration alone may not provide enough runoff reduction to meet regulations. That’s why rainwater harvesting is an important tool to help meet runoff reduction requirements.
The DuroMaxx Rainwater Harvesting Cistern will help achieve stormwater management goals by reducing stormwater runoff while providing residual cost savings through the reduction of potable water use.
Contech's Runoff Reduction Calculator allows you to input supply sources (rooftop runoff, condensate,..) and demand criteria (seasonal irrigation demand, toilet flushing…) to determine the benefits of a rainwater harvesting system. With the Runoff Reduction Calculator, you can:
- Calculate Runoff reduction, stormwater volume retained on-site, water savings, and reduction of demand on potable supplies
- Optimize cistern size
- Determine financial savings based on water usage reduction
- Compile data to support LEED Credits
- Generate reports for stormwater permit approval
The Runoff Reduction Calculator simulates runoff reduction and water collection based on daily analysis using over 20 years of local rainfall data. A detailed report including projected performance calculations is automatically generated that can be used for client meetings and stormwater permit approval.
Rainwater Harvesting Pretreatment Devices
Pretreating stormwater prior to storage protects downstream pumps, filters, and fixtures from damage or clogging, and lowers cleaning and maintenance costs by keeping pollutants out of the cistern and mechanical system. Contech offers a number of pretreatment devices including:
The CDS hydrodynamic separator is the preferred rainwater harvesting pretreatment device. CDS is an underground stormwater treatment device that uses swirl concentration and continuous deflective separation to screen, separate and trap trash, debris, sediment, and hydrocarbons from stormwater runoff. With CDS there is no need for “first flush” diversion, so no water is wasted.
CDS captures and retains 100% of floatables and neutrally buoyant debris 2.4mm or larger and removes solids down to 100 microns. It is the only non-blocking screening technology available in a hydrodynamic separator. With large pollutant storage capacity and treating flowrates up to 1 cfs, the CDS can treat runoff from large areas with minimal maintenance.
Other pretreatment options include:
StormFilter uses rechargeable, media-filled cartridges to absorb and retain the most challenging target pollutants including dissolved metals, hydrocarbons, and nutrients metals and other common pollutants found in stormwater runoff.
The Jellyfish Filter is an engineered Stormwater quality treatment technology featuring pretreatment and membrane filtration in a compact stand-alone treatment system, which removes a high level and a wide variety of stormwater pollutants.
DuroMaxx Rainwater Harvesting Cisterns
The DuroMaxx Rainwater Harvesting Cistern is made from DuroMaxx Steel Reinforced Polyethylene (SRPE). The eighty (80) ksi steel reinforcing ribs provide the strength and pressure rated polyethylene (PE) resin provides the durability. The combination of materials results in an extraordinarily strong and durable below ground cistern.
- Available up to 120” diameter
- Includes prefabricated access points
- Lightweight - easily handled and quickly installed, often without the use heavy construction equipment
- H-25 traffic rated design
Contech’s DuroMaxx Rainwater Harvesting Cisterns have been certified to be in compliance with the Uniform Plumbing Code (UPC®) by The International Association of Plumbing and Mechanical Officials (IAPMO) Research and Testing. Engineers can now write specifications for rainwater harvesting tanks based on a nationally recognized standard that address issues such as structural design, leakage, and repeatable manufacturing processes. Contech is only one of two companies that have received IAPMO/UPC certification for rainwater harvesting tanks.