If you’ve ever been confused about the cover requirements over underground detention systems, you’re not alone.  Why do the requirements change during construction vs. post-construction? Let’s break it down. What is Underground Detention System Cover?First, let’s start by defining what cover is so that we’re all on the same page. Cover is

High-flow bioretention systems target the removal of suspended solids, total and dissolved nutrients and metals, oil and grease, trash, and debris. Components typically include plants, mulch and specially designed filter media mixtures often contained in a concrete container. The mulch layer and filter media capture and immobilize pollutants during

High rate biofiltration continues to gain acceptance within the regulatory and engineering community as an acceptable alternative to traditional bioretention. These systems provide high treatment levels in a compact size making bioretention feasible on sites where traditional bioretention is not possible. They have earned numerous agency approvals

“One’s company, two’s a crowd, and three’s a party” may not exactly apply to manufactured treatment devices (MTDs), but hopefully, this post can offer some insight that will make designing multiple MTDs in parallel a little more fun.It is common practice to utilize different Best Management Practices (BMPs) in series or “treatment trains” to

ASTM International (ASTM) has been a recognized leader in consensus standard development by many different industries for more than 100 years now.  ASTM’s newest technical committee, E64, is devoted specifically to developing standards applicable to the broad class of stormwater management practices known as stormwater control measures (SCMs). 

As cities grow and expand, we hear the word redevelopment tossed around more frequently. But what is redevelopment? In its most simplistic definition, redevelopment is the action or process of developing something again or differently. How that applies to the civil site world is any new construction on a site that has pre-existing

Since its inception in 1996, The International Stormwater BMP Database  has been archiving performance, design, and cost data for stormwater treatment best management practices (BMPs) in a publicly accessible database.  At this point, over 600 BMP studies have been added, providing a wealth of information to regulators, engineers, academics, and

Sloping fills over underground corrugated metal pipe (CMP) is an obstacle and consideration when choosing a suitable stormwater detention location. While it is always preferable to place underground detention systems on locations with no slope, that is not always possible. Any given project site may contain several slope geometries or profiles that

Oil changes. Gutter cleaning. Annual doctor appointments. These are all forms of maintenance that most people would likely agree are necessary to keep our vehicles, our homes, and our bodies in good working order. We may not like spending the time, money, and effort on these tasks, but we do them anyway.If you happen to own a stormwater best

Many manufactured stormwater filtration systems use media-filled cartridges. During a storm, runoff passes through the filtration media, which absorbs and retains pollutants from stormwater runoff, including total suspended solids, hydrocarbons, nutrients, metals and other common pollutants. The structures that house the filter cartridges can be

Perhaps stigma is too strong a word, but for those that have been around storm water management circles a while, it’s hard to ignore the fact that manufactured storm water treatment devices (MTDs) continue to live in the shadows despite more than two decades of innovation, performance data and contributions to the storm water management sector at

In the part one of this blog series, we looked at Factors That Drive MTD Maintenance Costs. These include time and equipment, disposal costs, and consumables.  Next, we explore the three factors that are most important to consider when designing MTD’s with maintenance in mind include access, location, and onsite logistics.AccessWhen talking about

Manufactured Treatment Devices (MTD's) are similar to non-proprietary stormwater BMP's in that they must be maintained so they perform as intended. However, the majority of effort and focus are typically placed upon the initial design and construction of stormwater treatment facilities, with little thought as to how these systems will be maintained

In part one of this series (Is 40% a Reliable Number?), we examined new research that showed the generally accepted number of 40% porosity (also hereby referred to as “stone voids”, and “void space”) within the stone backfill as available storage might not be a reliable number. To obtain a 96% reliability in stone storage, 36% stone void storage

Stormwater detention systems often include a large portion of the storage volume within the voids of the backfill material. Depending on the underground structure design and size, allocated storage within the stone voids can vary between 25-60% of the overall storage for the project. The generally accepted number has been 40% stone void space.

One of my favorite summer activities is floating in the water and looking up to the sky. For some, like me, floating can be relaxing, but for others, floating brings an uneasiness. When floating, one must trust the physical force at play – a force known as buoyancy. When trying to float in the ocean, buoyancy is a good thing. In the case of an

Many say that if it looks and quacks like a duck, then it’s probably a duck. When you visualize a biofilter, you might envision bioretention cells, rain gardens, constructed wetlands, bioswales, or vegetated filter strips. What is a visual commonality among these practices? Plants. Following the duck test, if it contains plants and engineered,

Contech has published several blog posts that refer to corrugated metal pipe (CMP) for underground storage of stormwater. We were a bit surprised when some engineers challenged our use of the word detention. Two different engineers commented on LinkedIn that the proper term to use was retention, not detention. Based on these comments, we thought it

Nearly twenty years ago, when I was cutting my teeth in a stormwater research and development laboratory, the debate over the most appropriate method to measure the solids concentration in stormwater samples was front and center.  The great total suspended solids (TSS) vs. suspended sediment concentration (SSC) deliberation.  Compounding the

Whether you are involved with the design, installation or the manufacture of stormwater BMP’s, the key ingredient to a successful project is communication.  Poor communication, or worse, no communication, can be a project's downfall. The best way to ensure excellent project communication is to have a pre-construction meeting.But why have a

Corrugated Metal Pipe (CMP) is the construction material of choice for underground stormwater detention and infiltration projects. With its low cost, a wide variety of pipe diameters up to 144”, layout configurations and pipe coatings, CMP offers engineers the flexibility to develop solutions that can be sized and shaped to meet site-specific

In the nearly 20 years that I’ve spent immersed in stormwater management matters (I’ve only actually gone in a couple of times), I’ve pondered many head-scratchers.  The proliferation of flawed policies, poor assumptions, questionable data and lack of enforcement have all been commonplace.  However, I have always been comforted by the fact that we

In last month’s blog post, we took a look at the Point on a Curve sizing methodology. In this month’s post, we will look at the other common HDS sizing methodology: the Net Annual sizing method. As a reminder, proper sizing should start by checking local regulations.The Net Annual method is used to determine an HDS system’s pollutant removal

Proper sizing of hydrodynamic separators (HDS) should start with checking applicable regulations. In many cases, local or state regulations will dictate how to size an HDS system and even provide a list of what products are approved for use.  If there are no regulatory requirements, the engineer must identify which pollutant(s) need to be removed

As a biofiltration surface layer, mulch can support water retention, weed suppression, organic replenishment, pollutant treatment, aesthetics, media protection from scour, and moderate media temperature. Landscape mulches can include organic mulches like fresh wood chips or aged composted mulch, as well as inorganic mulches such as rock and rubber

Installing a Stormwater BMP is an important step towards protecting our waterways, but for them to perform as designed, they must be maintained regularly. Where do we dispose of the material removed from catch basins and stormwater treatment systems after maintenance?  I get that question regularly from both private and municipal maintenance

At the heart of every bioretention system is the media that captures and immobilizes pollutants that are then decomposed, volatilized and incorporated into the biomass of the system’s micro/macro fauna and flora. Bioretention media cannot be the heart of the system removing the intended pollutant load when flow rate is compromised due to premature

Let’s start by stating what I would consider to be an obvious fact: all Stormwater BMPs require maintenance. Whether we are talking about public domain or manufactured treatment devices, they all need routine maintenance to ensure they operate efficiently over extended periods of time.Maintenance is defined as the routine recurring work required to

I would consider myself a big picture thinker, always seeking to understand the full story, including the whys and how’s of a given situation.  I also like to probe below the surface and get my head around the root of a problem since that’s where the lasting solutions are usually found.  When I look around the full breadth of the stormwater

Three Components of Infiltration System DesignCommon infiltration practices include drywells, bioretention, permeable pavement, infiltration trenches, infiltration basins, and subsurface infiltration galleries. Regardless of their form, all infiltration systems have three primary components: storage, treatment, and infiltration.1. StorageRetention

An appropriately designed and manufactured high performance biofiltration system combines the benefits of natural biofiltration with the reliable and predictable performance of an engineered system. Each high performance biofiltration system utilizes a multifaceted approach including physical, chemical and biological processes to capture,

It’s that time of year again - temperatures have dropped below freezing, and the wintery weather has blown in. Departments of Transportation, state, local and city road crews are being kept on their toes, applying roadway treatments and safe passage for all of us. It is estimated that the US spends approximately $2.3 billion annually to keep highways free of snow and ice, and roughly 20% of transportation department budgets goes toward winter road maintenance.

As the New Jersey Department of Environmental Protection’s (NJDEP) certification program for Manufactured Treatment Devices (MTDs) has evolved over the years, one thing has remained consistent.  Confusion among stormwater professionals regarding the role that NJDEP plays vs. the role that the New Jersey Corporation for Advanced Technology (NJCAT)

Enjoying a spectacular fall in Portland, Oregon leads me to talk about street trees and leaves.As we all know the value of trees extends well beyond stormwater management.  Urban trees provide numerous benefits including providing wildlife food and habitat,  reduction of the heat island effect (up to 4 degrees C)  and reduction in CO2 emissions and

We’ve all heard the expression “can’t see the forest for the trees,” but when’s the last time you can remember it applying to yourself?  As a stormwater engineer, I’ve spent 15 years focusing on the design of natural systems and manufactured devices that treat and/or infiltrate post-construction runoff, and there is ample opportunity to get lost in

There are certain hazards with any profession. For a stormwater engineer, mine takes the form of gentle teasing from friends and family as I stoop in parking lots peering down grates into the abyss.What am I looking for? Well, like most stormwater infrastructure, nearly every Contech product is buried. My work is completely hidden underground!

Hydrodynamic Separators (HDS) – often referred to as oil-grit separators, swirl devices, or vortex separators – are best management practices often used to remove sediment, hydrocarbons, trash and debris from stormwater runoff.  HDS units are regularly used as either standalone treatment devices or pretreatment systems to detention, infiltration,

When it comes to using hydrodynamic separator (HDS) treatment devices, it is becoming commonplace to integrate them into storm sewer networks without worrying about the hydraulic impact of the device. After all, the majority of these devices are manholes or vaults with flow-through treatment, which are seemingly uncomplicated when compared to those

With stormwater pollutant removal requirements increasing nationwide, the demand for robust filtration has also increased.  Designing and specifying a properly functioning filter extends beyond specifying the correct product (media or membrane filter) and sizing correctly (flow or volume based).  These additional considerations are classified as

For this issue of the Stormwater Blog, I thought it would be beneficial to include a short video to better visually illustrate the durability and general advantages of Aluminized Type 2 (ALT2) corrugated steel pipe (CSP) detention/infiltration systems.The protective coating of aluminized type 2 corrugated steel pipes is composed of a free aluminum

One could argue that plants are the most essential part of biofiltration systems such as bioretention, high performance biofilters, and rain gardens.  However, plant design presents a unique challenge for system designers.  What types of plants should be selected?  Will they work well in the system? Will they be aesthetically pleasing?  Designing a

The International Stormwater Best Management Practices (BMP) Database project website (http://bmpdatabase.org) features a database that includes over 600 BMP performance studies.  This is a tremendous free resource for engineers, scientists, policymakers and others who seek to characterize the pollutant removal and hydrologic performance of various

In a previous post (Don’t Bypass Good Design Part 1: Offline Vs. Online Diversion Structures), I wrote about bypass structures and argued that they deserved more attention. In this follow-up, we’ll do just that by comparing two different ways to divert flow in a precast manhole. Option One: Using a manhole with different elevation outlet pipes With

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

Months of design, pages of specifications, and tens or even hundreds of thousands of dollars may go into the design of a single bioswale, filtration basin, or other stormwater treatment system. So why do we spend so little time thinking about the flow control devices that make them work? This article is part one of a two-part series on bypass

Oh stormwater treatment performance lab testing, your time-consuming, methodical steps make me want to pull my hair out. You often leave me with more questions than answers. However, the benefits often counterbalance the challenges. Thank you for answering my questions, even if I must endure the tedious steps of the scientific method; a method that

I had an interesting sequence of thoughts after watching my 12-year old daughter chat with a friend on her cell phone about a music video they were simultaneously streaming on their laptops.  It’s easy to marvel at a kid’s fluidity with technology that didn’t exist when they were born, but I realized that I, too, experienced this rapid adoption of

Read Part 1: Frustration is a Two-Way Street The initial wave of manufactured treatment devices (MTDs) were generally simpler than options available today.  With few exceptions, early MTDs were comprised predominantly of swirl/vortex and other types of gravity separators that targeted solids and floating pollutants.  State and local stormwater

Having spent the last sixteen years immersed in the world of stormwater best management practices (BMPs), with particular emphasis on manufactured treatment devices (MTDs), I’ve repeatedly borne witness to the frustrations, misperceptions, and concerns raised by all walks of stormwater professionals relative to MTDs.  They’re too complicated, you

This month’s blog post comes from Janice Kaspersen, editor of Stormwater magazine. Did you drive to work this morning? Was a parking space waiting for you when you arrived? Many cities require developers to provide a minimum number of parking spaces for office, retail, and residential buildings; sometimes the number is based on the square footage

Given the number of conversations I’ve had in recent months with other stormwater professionals that don’t entirely understand the value of incorporating the sediment mass load capacity of a filtration BMP into the design process, I feel it’s time to revisit the subject.  We tend to think about BMP design in terms of treatment capacity which is

There are several factors to consider when selecting the most appropriate stormwater filtration solution for a specific site.  Several of these factors easily come to mind, such as: state or jurisdiction regulations, hydraulic grade line limitations, footprint constraints, and other site restrictions.  One variable that is often overlooked when

Why we need risers?If you’ve ever walked down a city street and stepped over a manhole with the label “STORMWATER” nestled in the pavement, chances are you’ve skimmed the surface of a detention system. If you were to lift up that manhole lid and peer down into its’ depths, you might be surprised to find a whole underground network of pipes and

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

As rainwater harvesting is becoming a more popular choice for stormwater management and runoff reduction, additional features are becoming available to allow for monitoring, report generation, and managing systems from a website interface.Just like many stormwater treatment systems, sometimes rainwater harvesting systems are forgotten about because

For the majority of applications, corrugated metal pipe (CMP) is the “go to” material for subsurface infiltration. This in turn, leads to a lot of design questions. Below is a list of six questions and answers we received from a recent webinar on designing CMP detention systems.1.  What are the design considerations for construction beneath

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

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

In our third and final part of our blog series we will look at design red flags for CMP detention systems. Red flags are design elements that are commonly or easily overlooked and may need extra attention when designing. Considering the red flags upfront will expedite the design and fabrication process, and eliminate delays, installation, and

In part one of this three part series we looked at the value of underground detention systems. In part two, we will provide insight in designing efficient and cost effective systems.Regarding minimizing costs, the three most importing goals should be to shrink the footprint of the system by maximizing the storage volume within a given area,

The two essential functions of a stormwater management system are to control the quality and quantity of runoff leaving a site. There are various ways to do this; a common method is with an above ground system in the form of a detention pond.The problem with ponds is that they take up usable land space therefore not allowing one to maximize their

With the passage of time and the placement of stormwater treatment facilities into service in urbanized areas, it’s been possible to observe how these facilities age. All too often, the majority of effort and focus is placed upon the design and construction of stormwater treatment facilities, which are often neglected or forgotten once construction

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

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

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

Rainwater harvesting (RWH) stores rainwater for reuse to supply non-potable uses like irrigation, wash water, toilet flushing, and laundry.  During long dry periods the demand will drain the storage cistern down to a critical level where the pressurization pump(s) will need to shut down to prevent dry run damage.  Make up water is typically a

As mentioned in Part One of this blog post series, a successful bioretention media installation must have a framework in place as guidance for managing media from inception to installation. The framework should not only include Standard Operating Procedures (SOPs) or how to source, qualify, verify, produce, store, and handle media, but also include

Engineered media is the heart of bioretention system performance. Therefore, preserving media integrity is of the utmost importance. A successful bioretention installation involves oversight not just onsite, but having a framework in place for transferring raw materials to a blended, commercially installed product. This framework should encompass

It’s never surprising to see some type of fabric or geotextile called-out around an underground detention or infiltration system. The note is common across civil plans everywhere, but how is a geotextile selected as applicable for the particular underground system the detail was so aptly created? The answer to that question starts with one step

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

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

As bioretention becomes more popular, many types of designs are being deployed throughout the U.S.  Though relatively simple in concept, many are finding that the devil is in the details with respect to maintenance and performance.  These issues are driving newer designs and improving criteria for use. Over my next few posts, I will be sharing some

We are an industry of abbreviations and acronyms. The terms we use on a daily basis can sometimes hold a general or broad meaning in our minds, but the actual definition of these terms may leave our thumbs hovering over the game-show buzzer. To help ease the furrowed brows, we have collected and defined the top 11 terms every Stormwater Engineer

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

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

Stormwater regulations are calling for an increased level of treatment. This often takes the form of filtration systems. Two types of filtration systems used in stormwater are media filtration and membrane filtration.Media Filtration systems function through physical capture of pollutants, as well as adsorption of pollutants through chemical

Most people do not think about how they get the water they use; they just turn on the tap and the water is there. The same holds true for rainwater harvesting (RWH) systems. Most people understand there is a cistern that collects and holds the harvested water. But what they may not realize is that with every large scale RWH system there is a

The only sure way to eliminate stormwater pollution is to eliminate stormwater runoff. In recognition of this fact, Green Infrastructure (GI) and Low Impact Development (LID) practices have prioritized runoff reduction as a primary regulation for stormwater management.  These practices have proliferated throughout the United States.Surface

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

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

Some engineers are hesitant to use corrugated metal pipe (CMP) 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).  The primary

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

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

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

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

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,

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

System hydraulics refers to how water flows through a stormwater filtration system. The following three steps should be part of the hydraulics evaluation process.1. Evaluate the hydraulic grade line (HGL) at the design flow rate. Typically, a backwater calculation from the point of downstream control should be performed to ensure the system can

Perhaps the most recognized Low Impact Development technique, bioretention, incorporates landscaped features to slowly percolate stormwater runoff through plants and engineered soil prior to infiltrating that water into native soils. Where feasible, these systems can be a low cost, high efficiency stormwater management practice that can also

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

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

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

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.As site conditions

1.   SizingSizing a cistern to meet Low Impact Development (LID) rules is challenging because most jurisdictions provide limited guidance, and existing tools do not yet include Rainwater Harvesting (RWH). Sizing is best done with a continuous daily simulation model that calculates runoff captured, overflow and runoff released, domestic water

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

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,

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

Infiltration plays an increasingly important role in meeting stormwater runoff mitigation regulations. One of the primary considerations for infiltration feasibility is the runoff routing.Infiltration systems must drain in a reasonable amount of time to avoid creating mosquito habitat and to recover storage volume for subsequent storms. Drain down

There are a wide variety of cistern materials to choose from. Because they are often smaller in size, residential systems offer more options, but not all will scale to tens of thousands of gallons in a cost-effective manner. This article focuses on commercial and institutional scale projects where storage requirements are thousands of gallons and

As the need for effective stormwater treatment and volume control grows, so does the number of available stormwater control measures (SCMs) such as filtration systems, hydrodynamic separators, bio-retention  systems, green roofs and pervious pavement. As part of their due diligence, engineers go through an evaluation process to determine if the

As a state stormwater regulator, I see many stormwater plans. These plans detail everything that would be done to protect water quality and prevent erosion. Yet even a well-written and well-executed BMP plan will not provide the intended service without proper maintenance.Recently, there has been a big push to implement more landscape-based BMPs

The City of Los Angeles Bureau of Sanitation received the Outstanding Stormwater Best Management Practice (BMP) Implementation Award for its Garvanza Park Stormwater BMP Project from the California Stormwater Quality Association (CASQA). The project had two primary goals: to reduce the amount of polluted runoff that enters storm drains, streams and

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

Factors Impacting Rainwater Harvesting ROI When you mention a commercial rainwater harvesting system (RWH) to an engineer, developer or owner, one of the first questions you get is “what’s the ROI?” Return on Investment and Net Present Value vary widely depending on specific project variables and there is no one correct answer.  The three largest

Mother Nature’s soil is the best of all urban stormwater Best Management Practices (BMPs). Precipitation infilitrates the soil, reduces runoff, filters and captures most pollutants, recharges groundwater, and maintains a diverse, self-sustaining biological community.Conservation of natural soils and urbanization are diametrically opposed. When

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

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

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

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all. These

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all.These were

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all. These

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all. These

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all.These were

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all. These

After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all.These were

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.

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

The Low Impact Development (LID) approach to site development and stormwater management is rapidly becoming the required design approach in many areas of the United States.The basic principle is to use nature as a model and manage rainfall at the source. This is accomplished through sequenced implementation of runoff prevention strategies, runoff

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

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

The task of selecting the proper stormwater BMP for your site can be tedious. There are thousands of choices; from drainage swales and silt fences to hydrodynamic separation and storm water filtration systems. All of them have their place in a well written BMP Plan, but none of them will work without maintenance. During my time as a state

A rainwater harvesting cistern is comprised of many components. Our experience is that some of these components are often overlooked, which can negatively impact water quality. Here is our list of the top five commonly missed rainwater cistern components and why they are important .1. Calming InletThe calming inlet reduces the velocity of water

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

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

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

This patented technology is employed by the Stormwater Management StormFilter in order to prevent surface blinding, ensure use of all media, and prolong cartridge life. In principal, the system siphons stormwater runoff through its cartridge.First, stormwater enters a StormFilter cartridge, percolates horizontally through the cartridge’s filter

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

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

If more than one type of infiltration system meets your project requirements, your decision may be cost driven. It’s important to maximize the storage efficiency in the available space at the lowest possible cost.Underground, Open-Bottomed Chambers This example highlights the need to evaluate multiple options and configurations to find the most

1. IrrigationIrrigation is the most common application for harvested water. Treatment requirements are lower, which makes the harvesting system simpler, and the demand can quickly drain the cistern to make room for the next storm event. However, relying solely on irrigation for net-annual runoff reduction is rarely enough. In most locations, there

Stormwater management is a broad topic, significant to us all.   It is important for the environment, there are endless regulations to abide by, an ever-expanding portfolio of products to choose from, budgets to meet and many opinions to consider. This is why we created The Stormwater Blog.At Contech, we have experts who have been in the stormwater

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

All stormwater BMP’s will require maintenance at some time or time interval. Long-term maintenance costs and maintainability are very important considerations. Here are some other things you should consider when discussing maintenance of your stormwater filtration system.1. Evaluate availability of maintenance contracting. It is the nature of

Water is necessary for economic growth, a healthy environment and vibrant communities for future generations. With gridlock in Washington and broken budgets at all levels of government, it may not seem like the right time to make broad changes in water management policy. But change is happening and the catalyst for that change is stormwater

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

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.