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The Stormwater Blog 

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

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Rainwater Harvesting Disinfection Methods: Treat It Before You Use it
Using harvested rainwater is not new, it has been in practice for thousands of years (3000 B.C., and may be even earlier).  But we have something that wasn’t available back then; the ability to disinfect rainwater to make it safe for human contact or ingestion.  Harvested rainwater can be safely used outdoors and indoors if the correct steps are taken to treat it. The type of disinfection depends on how the water is going to be used and the requirements of local plumbing codes.  With modern disinfection, rainwater can even be filtered and disinfected to potable standards.
6 Key Points of Developing a Stormwater Trash Control Strategy
In my last blog post, What Kind of Trash and Debris is in Stormwater Runoff?, I wrote about the types of trash found in stormwater and the effects trash and debris have on our environment and infrastructure. 

Continuing with the topic of trash control; if your community is interested in developing a trash control strategy here are six key points that should be considered
Is Corrugated Metal Pipe Suitable for Subsurface Infiltration?
Some engineers are hesitant to use CMP (corrugated metal pipe) for stormwater applications because they have read or heard about CMP being used in culverts that have corroded. This shouldn’t be the case. Many decades ago, galvanized pipe was the coating of choice for culverts; that now has been replaced with Aluminized Type 2 (ALT2). 
Categories: Infiltration
Why Filter Stormwater?
Remember when stormwater filtration was at the forefront of runoff water quality treatment?  Have the variables and performances that led to its successful history been displaced by recent Green Infrastructure (GI) or Low Impact Development (LID) initiatives, or is filtration a viable partner in the GI and LID arena?  Boiling it down, why should we filter stormwater?
What Kind of Trash and Debris is in Stormwater Runoff?

We all know that stormwater runoff carries trash and debris into our water ways, but have you ever wondered what kind of material this runoff picks up?

A Contech Continuous Deflective Separation unit (CDS) was installed on a site in California and the performance of the unit was monitored over a 12 months.  During a maintenance event, the trash and debris that was captured by the CDS was removed, and the contents were separated and characterized. 

Stormwater in the west: Use it or lose it!

At about 2.5% of the total water volume on the planet, we’ve always had roughly the same amount of freshwater. Unfortunately, it seems that, at the local level, the amount of fresh water made available through precipitation is increasingly erratic, with the last year featuring historic floods in the eastern US and historic drought in the west. In my adopted home state of California, 2013 was officially the driest year on record and snowpack, groundwater and reservoir levels throughout the state are critically low. Although we’ve undertaken extensive engineering feats in the form of reservoirs, diversions and water supply pipelines, local water management decisions provide our greatest leverage on local water supply.

Stormwater Infiltration Explained

Stormwater infiltration is defined as the process by which water enters the soil and recharges streams, lakes, rivers, and underground aquifers. Stormwater infiltration is a fundamental component of the water cycle and is quickly becoming the centerpiece of stormwater management strategies across the United States. Stormwater infiltration is an effective means of managing runoff because it allows practitioners to address both water quality and water quantity concerns.

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”

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.

Three Steps to Evaluate Stormwater Filtration System Hydraulics

System hydraulics refers to how water flows through a stormwater filtration system. The following three steps should be part of the hydraulics evaluation process.

Categories: Treatment
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