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Over the last 20 years of site-civil design, it has been interesting to see stormwater trends come and go.  Some design methodologies have disappeared, only to return later or in a nearby geography as the “new” approach.  Agency directives can shift based on new leadership or the prevalent regional concerns at the time.  As the construction

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Hydrodynamic Separators (HDS) have been used in the stormwater industry for over 20 years.  They are effective at removing TSS, hydrocarbons, and trash and debris from stormwater runoff and are often used for standalone treatment or pretreatment to filtration, detention, infiltration and rainwater harvesting system.  With the varied applications

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Plants provide fresh oxygen to breathe and beautiful aesthetics that can take our breath away, but many people don’t think about the role plants can play in stormwater treatment. The principal notion of Low Impact Development (LID) is founded upon mimicking pre-development conditions. Part of mimicking pre-development conditions includes not just

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The question of whether a hydrodynamic separator should be online vs. offline is something that engineers and stormwater treatment manufacturers deal with on a daily basis.  Online systems allow storm events that are greater than the design storm to be bypassed through the treatment unit, eliminating the need for a separate bypass structure.  This

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Current stormwater design guidance typically recommends starting with preservation of the natural landscape and hydrology wherever feasible. But, even with preservation, new stormwater management facilities are likely to be required to capture and clean runoff from pollution generating surfaces. These new stormwater facilities are likely to include

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EPA selected a removal standard of 80% total suspended solids (TSS) removal as the target pollutant of concern due to high TSS concentrations ubiquitous impact on water quality and degradation to aquatic habitat. Many other pollutants of concern are particle-bound, and TSS is thereby a surrogate for other pollutants. Testing methodologies for

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The EPA selected a removal standard of 80% total suspended solids (TSS) removal as the target pollutant of concern due to high TSS concentrations impact on water quality and degradation to aquatic habitat. Many other pollutants of concern are particle-bound, and TSS is thereby a surrogate for other pollutants. Testing methodologies for stormwater

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Bioretention Part Three: Lessons Being Learned – Siting Issues and Inlet DesignNot done with siting issues yet, maybe this becomes five parts?   One issue on siting and design is the hydraulic grade lines.  Recall from your road drainage days the equations that were used to space catch pits and throat openings?  The equations allowed for you to

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As a volume based stormwater control measure, bioretention systems are providing beneficial use in that they reduce runoff volumes and peak flows. In areas where combined sewers are an issue, bioretention can reduce CSO frequency while increasing evapotranspiration and helping with groundwater recharge via infiltration processes. Common design

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The goal of the TMDL program is arguably simple - to develop watershed level conservation plans designed to restore impaired waters and attain applicable water quality standards – but its development and implementation has not been simple. In an attempt to bring new clarity to the process of incorporating TMDLs into stormwater permits, the EPA

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There are a vast number of stormwater separators on the market which can make it challenging when selecting the ideal solution for each project.  Hydrodynamic separators and oil/water separators are often used interchangeably in the industry but each system is unique and one may be better suited for the overall treatment goals of the project.   So

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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

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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

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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

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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

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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

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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

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Drafting stormwater regulations that are clear, comprehensive and effective is crucial to protecting and preserving receiving waters.  The Clean Water Act has yielded a wide spectrum of local stormwater regulations and policies, but many leave something to be desired when it comes to actually mitigating the impacts of urban runoff.  It has been our

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As an industry, we’ve acquired a vast amount of knowledge about stormwater, its adverse impacts, and the best management practices (BMPs) implemented to mitigate them. However, the spirited debate with regard to whether the field or the laboratory is the best arena for evaluating BMP performance refuses to yield to consensus. Here are some of the

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Stormwater policy is put in place to control non-point source pollution and is usually tied to the National Pollution Discharge Elimination System Permit (NPDES).Implementation tends to take a while – not for a lack of desire to protect our water resources, but because it is often challenging to integrate stormwater policy through the existing

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Given the limitations and challenges inherent of BMP evaluations, whether done in the field or the laboratory, it’s a wonder we bother with either. However, the intent of identifying these issues is not to discourage evaluation, but to foster understanding so as to encourage BMP evaluations to be structured in a manner that yields sound results.

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Having worked in the field of stormwater management for almost 20 years, and seeing the conceptual and technological development of stormwater management and BMPs, it is clear we have had successes and failures.We need to learn from both, especially with USEPA’s national rulemaking activities to establish a program to reduce stormwater discharges

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The removal of site-specific pollutants can be maximized with the variety of filtration media available. Understanding the hydraulics of the media you choose is a key, albeit misunderstood, factor in determining the effectiveness of the filtration system. Here are five things you should consider.1) Evaluate the specific flow rate (q) through the

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An increasing challenge that we see with our customers is balancing water quality with water quantity. Conventional design would be to use an in ground detention pond. But, if this is not an option, whether the owner does not want the aesthetics of a pond, the land needs to be used for parking, or you have a layer of clay soil that makes

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Innovation has become synonymous with the United States, serving as a catalyst for our economic growth and continuous improvement of our standard of living.Economics aside, if not for innovative scientific and technological breakthroughs we would be without countless apparatuses, methodologies, and other discoveries that now serve as solutions to

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An appropriately designed and manufactured tree box filter combines the benefits of natural biofiltration with the reliable and predictable performance of an engineered system. Each tree box filter utilizes a multifaceted approach including physical, chemical and biological processes to capture, immobilize and treat harmful pollutants, while also

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During the past few years, a number of different filter media have been used for stormwater filtration. Media such as sand, peat, and compost have been used successfully. Recent uses of perlite, zeolite, carbon, and other “exotic” media have expanded the choices for targeting specific pollutants. Here are some questions you should ask when

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The intent of LEED Sustainable Sites Credit 6.2 is “to limit disruption and pollution of natural water flows by managing stormwater runoff,” and the requirements necessary for meeting this intent are clearly spelled out: capture 90% of the average annual rainfall and treat it by removing 80% of the total suspended solids (TSS). While the rating

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By now, you’ve probably heard of triple bottom line accounting, a full cost accounting approach considering the economic, environmental and social impacts of a decision or more poetically, the three P’s: people, planet and profit. In the stormwater infrastructure planning world, as in many other urban planning arenas, this approach is gaining

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As an industry, we’ve acquired a vast amount of knowledge about stormwater, its adverse impacts, and the best management practices (BMPs) implemented to mitigate them. However, the spirited debate with regard to whether the field or the laboratory is the best arena for evaluating BMP performance refuses to yield to consensus. Here are some of the

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Filtration CharacteristicsMedia Surface AreaFiltration flow rates are typically expressed as a surface area specific operating rate such as gallons per minute per square foot (gpm/ft2) of surface area. Lower specific operating rates translate to better performance and longer maintenance cycles. Specific operating rates higher than 2 gpm/ft2 of

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Filtering stormwater is an effective way to remove the most challenging pollutants from urban runoff - including fine solids, soluble heavy metals, and total nutrients. Though the physics of filtration are the same, there are many variables to consider when designing a stormwater filtration system. It’s important when designing a filter treatment

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As the economic downturn continues to shrink state coffers budget cuts have rendered numerous government programs nearly inoperable. Unfortunately, stormwater management and other water quality initiatives have not been spared from a similar fate.Considering that many state and municipal stormwater programs were already operating with a skeleton

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Inspection and maintenance are key factors for making sure that your biofiltration box is performing as designed and achieving the required water quality standards.  Here are a few things to keep in mind...1. Protection from Construction DebrisBioretention box soil must be protected from compaction by heavy equipment traffic during construction.

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