The Stormwater Blog 

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

Maintenance Resiliency of Stormwater Treatment Facilities
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 is complete. Depending on circumstances, this often results in deferred (if not nonexistent) maintenance of these facilities, which only worsens with time as the facilities age and accumulate collected pollutants with each passing year.
Categories: Maintenance
Rain Gardens Not Permitted?

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 imported soil or soil amendments that add permeability and/or optimize soil structure for vegetative growth. For many years, the industry has characterized media in vegetated facilities generically as soil, sand, compost, etc.

All Stormwater Particles Are Not The Same Part 2: Particle Shape And Density

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 stormwater control measures (SCMs) in respects to TSS can vary greatly. There are many sediment characteristics that should be considered when evaluating a SCM for TSS removal performance to ensure apples and apples are being compared among removal efficiencies for SCMs.

All Stormwater Particles Are Not The Same. Part 1: Particle Size And Composition

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 control measures (SCMs) in respects to TSS can vary greatly. In part two, we’ll continue our look at stormwater sediment and discuss particle shape and density and their affect on TSS removal.

Rainwater Harvesting and Make Up Water: The Why, When, and How

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 potable connection to the rainwater harvesting system to supply water, allowing the RWH system to continue to supply the non-potable end use applications until the next storm event refills the storage cistern.

Guidance for Ensuring Bioretention Media Performance Success Part 2: Specifications, QA/QC and Certification
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 media specifications to ensure recipe consistency.
Categories: Bioretention
Guidance for Ensuring Bioretention Media Performance Success Part 1: Standards of Practice
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. 
Categories: Bioretention
Filter Fabric in Detention and Infiltration Systems

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 back – why we even use filter fabric.

Bioretention Part Three: Lessons Being  Learned – Siting Issues and Inlet Design

Not 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 estimate gutter efficiency and top width for specified design storms. Well, these equations still apply, and I am thinking maybe even more considerations for very low flows.

Bioretention Part Two: Lessons Being Learned - Design Considerations

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 criteria include storage volume and a design infiltration rate of the media and the underlying native soils. These criteria are tied to the site characteristics and statistical hydrology, for example, design the storage volume such that 95% of the mean annual runoff volume is retained. In addition to these sizing criteria we also need to design with these other factors in mind.

Page 1 of 8First   Previous   [1]  2  3  4  5  6  7  8  Next   Last