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The Stormwater Blog 

Contech Stormwater experts discussing Low Impact Development, Onsite Water Management, Rainwater Harvesting and all things Stormwater.

Stormwater Control Measures: Are We Capturing All the Costs?

By Jim Lenhart  |  Friday, June 20, 2014  |  395 Views
Stormwater Control Measures:  Are We Capturing All the Costs?
Most models and approaches toward cost accounting of Stormwater Control Measures (SCMs) use standardized engineering economics. These models use the first cost and annualized O&M costs, brought forward to present value using assumed interest rates, etc. Models that are more sophisticated will break the first costs down to show engineering design, project administration, land, and construction costs. O&M costs can be segmented for minor and major operations. In some models, costs are estimated from a statistical database based on costs from other projects. For example, the cost of pond maintenance is estimated on data from ten case history’s which are normalized to the area of the pond. Others are based on unit costs of labor, equipment, disposal costs, administration, etc. Each method has its advantages and drawbacks. However, my guess is that both methods lack the precision that people are looking for, and is some cases, are underestimating or overestimating costs.

Phosphorus Leaching from Bioretention and Green Roofs: The “Dirty Little Secret”

By Joel Garbon  |  Monday, June 09, 2014  |  917 Views
Phosphorus Leaching from Bioretention and Green Roofs: The “Dirty Little Secret”
Bioretention and green roofs have become the centerpieces of Low Impact Development (LID) initiatives throughout North America. The well-publicized benefits of these two types of stormwater management practices focus on runoff reduction, stormwater quality treatment, and landscape aesthetics. Promotional literature provided by various regulatory agencies and environmental organizations typically highlights the processes and mechanisms within bioretention and green roofs that provide desirable outcomes. Normally, one finds mention of evapotranspiration, filtering, and adsorption characteristics of the vegetation and soil mix as beneficial mechanisms for the purposes of runoff reduction, particulate and hydrocarbon removal, and dissolved pollutant capture, respectively.

Evaluating Media for the Filtration of Stormwater

By Jim Lenhart  |  Tuesday, May 13, 2014  |  965 Views
Evaluating Media for the Filtration of Stormwater

During the past decade, a number of different media have been used for stormwater filtration and more recently for bioretention. Media such as sand, peat, and compost have been used successfully. Uses of perlite, zeolite, carbon, and other "exotic" media have expanded the choices for targeting specific pollutants. Media are now being used to target TSS, Petroleum Hydrocarbons, Dissolved Phosphorus, dissolved metals and even bacteria. More recent research in biofiltration adds elements of biological uptake of nutrients and metals by plants, conversion of Nitrogen into ammonia in anaerobic zones.

Categories Filtration, Treatment

Is Green Infrastructure Diminishing Innovation?

By Derek Berg  |  Monday, April 07, 2014  |  1582 Views
Is Green Infrastructure Diminishing Innovation?
Since the Environmental Protection Agency, and in turn state and local regulators, have gone all in on green infrastructure (GI) and low impact development (LID) concepts a seemingly regrettable consequence has emerged.  Topics specific to the broader adoption and implementation of GI have monopolized our collective dialog on stormwater management of late.   The predominantly positive press and barrage of GI heavy conference agendas seemingly suggest that if we apply GI far and wide then water quality impairments caused by urban runoff will soon be a thing of the past.  GI provides stormwater practitioners with invaluable tools to aid in the stormwater fight, but many site specific challenges can’t be surmounted with GI solutions alone.  To that end, should we be concerned that overemphasis on GI is discouraging innovation?
Categories Regulations, Treatment

Three Maintenance Tips For Your Rainwater Harvesting Cistern

By Kathryn Thomason  |  Thursday, March 06, 2014  |  1767 Views
Three Maintenance Tips For Your Rainwater Harvesting Cistern
All stormwater systems need to be maintained to continue operating effectively, and rainwater harvesting (RWH) is no exception. Unfortunately, many owners do not care that their stormwater BMP is not functioning due to lack of maintenance. Maintenance of RWS systems is critical for owners that depend on their continued operation and associated utility savings. Proper maintenance of a RWH cistern helps protect water quality and ensure system performance.

Why Pretreat Your Stormwater Infiltration System?

By Hannah Schlachter  |  Tuesday, February 11, 2014  |  1530 Views
Why Pretreat Your Stormwater Infiltration System?
Hands down, the most important factor in the sustainability of any infiltration system is proper maintenance. By their very nature, infiltration systems are difficult to inspect and maintain. The selection of a cost-effective and easy-to-access treatment system can mean a huge difference in maintenance expenses for years to come.
Categories Detention, Maintenance

Four Rainwater Harvesting Cistern Design Considerations

By Kathryn Thomason  |  Monday, January 06, 2014  |  1705 Views
Four Rainwater Harvesting Cistern Design Considerations
Rainwater Harvesting does not have a long history of use in modern site design, but now that it is a topic of interest, many engineers have questions about this new practice. Many of these questions center on cisterns, which are at the heart of every rainwater harvester system. This post looks at four rainwater harvesting cistern design considerations – sizing, design life, structural capacity and installation.

Thinking Outside The Box: Infiltration System Layouts

By Duane Herring  |  Monday, December 09, 2013  |  2418 Views
Thinking Outside The Box: Infiltration System Layouts

Historically, underground infiltration beds have been laid out in either square or rectangular shapes, sometimes far away from where the actual rain drops fall. These large systems are typically fed by a series of upstream catch basins and conveyance pipes. Several factors contribute to site layout, but mostly it simplifies the hydrologic and hydraulic modeling process, and keeps infiltration beds away from more sensitive underground infrastructure.

Leaves, Trees, and Stormwater BMPs: Designing with Maintenance in Mind

By Sean Darcy  |  Tuesday, November 05, 2013  |  1704 Views
Leaves, Trees, and Stormwater BMPs: Designing with Maintenance in Mind

Preserving large trees as runoff interceptors is an integral part of low impact development as well as incorporating trees and vegetation in filtration beds, rain gardens, and bioretention systems. These systems are extremely beneficial and provide essential functions of the natural landscape: infiltration, evaporation, transpiration, interception, and shading.

Depending on the type of tree or vegetation retained on-site or planted within the facility there is a different type of load released throughout the year….organic matter. Organic matter for a green field is extremely beneficial as the load can easily be assimilated, allows for decomposition, and provides essential nutrients for soil and nourishment for future vegetation. Organic matter for a stormwater facility can be beneficial, but also can increase excessive nutrient loads that cannot be assimilated, block inlets, blind surface beds, alter flow paths, and change percolation rates through the soil.

Eight Benefits of Stormwater Treatment Trains

By Hannah Schlachter  |  Thursday, October 10, 2013  |  2383 Views

Traditional stormwater criteria require both improving the quality and managing the quantity of runoff. One of the best practices is to incorporate pretreatment, detention and treatment into an integrated system. This approach can meet total daily maximum load requirements by providing a high level of pollutant removal and preventing erosion damage from peak flows. Many areas may require only some of these processes while some areas may require all of them. Here are eight benefits of using this three-tiered approach to stormwater treatment:

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