Have you ever repeated this lesson to yourself from the famous fable of The Tortoise and The Hare? The main takeaway being that consistent, deliberate effort will ultimately lead to success. I was reminded of this over the weekend in the gym, as I am recovering from a back injury and working hard to get back to pre-injury condition. As seems to be the norm these days, I am looking for instant results, but my lifting partner reminded me that consistent and steady strides are key. As I tried to calm my frustrations, it dawned on me that I have been preaching consistency and this same tale over the past year in working with regulatory agencies on storm water management issues, especially as they begin to develop or update their programs and performance protocols relative to manufactured treatment devices (MTDs).
As agencies recognize that there is certainly a need for MTDs that can comply with water quality regulations, the next topic of discussion becomes how to establish a sound MTD program to ensure all approved technologies provide the desired level of water quality improvement, which can be challenging. Public domain systems such as green infrastructure practices often have prescriptive design standards written into best management practices (BMP) manuals, but the fact sheets around MTDs are often more generic in nature with limited detail on proper design. Some design guidelines may be included, such as targeted pollutants, recommended distance from a paved surface for maintenance access, or general footprint considerations while some manuals say to reference manufacturers’ information regarding performance claims and functionality. However, with the different types of technologies available and the fact that design criteria vary based on treatment goals, developing consistent performance standards and following through with consistent implementation are the foremost important aspects of a successful MTD program.
This is a topic that could expand well beyond a blog post to fully cover (some performance protocols alone are dozens of pages), but we will just touch on a few of the critical points.
The first essential ingredient of a successful MTD program is to establish consistent performance standards. It is sometimes easiest to do this by going through a list of targeted questions:
- What are the target pollutants of concern – is removing coarse TSS sufficient to meet water quality goals, or do dissolved pollutants need to be targeted? This is the first key in determining the types of acceptable MTDs and technologies. A hydrodynamic separator is effective at capturing sediments but a filter system is needed for dissolved pollutants, and each functions very differently.
- What is the target level of performance? Catch basin inserts and hydrodynamic separators both target sediments, solids, and trash. However, each provides a different level of treatment based upon functionality and has differing maintenance requirements.
- What testing protocol will be followed to ensure that all approved MTDs provide equivalent treatment and also are designed to provide equivalent performance to other types of BMPs? A consistent performance protocol must be developed for MTDs to test to and comply with in order to verify treatment claims and provide consistency in functionality. Sound protocols set the boundaries that manufacturers must adhere to when conducting testing in order to verify performance. Major items of performance protocols include particle size distribution, sampling methods, and scaling; however, less common parameters, such as water temperature during testing, also can have a significant impact on testing results.
- How will approved MTDs be sized? Many municipalities provide a calculation for determining water quality volume, but MTDs are usually flow-based systems. Clear, consistent methods should be provided for sizing, either by providing water quality flow calculations or outlining acceptable methods to convert the water quality volume to a flow.
Once performance standards and protocols are established, consistent implementation of the program becomes crucial. Having a written and documented policy will ensure that the program continues to be steadily implemented even when facing circumstances such as staff turnover or atypical design conditions.
If resources such as time, expertise or political will are not in place for an agency to develop its own MTD program, there are other reputable and established programs to build from or reciprocate.
Specificity and consistency do not only benefit municipalities in complying with MS4 permit conditions and simplifying the plan review process. An MTD program also benefits design engineers by clarifying what is necessary to meet regulations, ensuring there are options available to treat runoff on constrained sites where land based systems can be impractical, and helps manufacturers understand what information to provide to designers and contractors. Consistency streamlines the design, review and even the installation process.
Lack of consistency in standards or implementation results in communities accepting varying levels of technologies. This leads to inequitable market conditions where price becomes the driver instead of performance in choosing which technology is used on a site, and often results in lower levels of treatment. Consistent performance standards and protocols will ensure that water quality improvements are the priority while also providing fair market conditions for manufacturers.
Throughout this post, I counted the words consistent or consistency 17 times. When it comes to implementing MTD programs, the lesson is the same as in so many other areas of life–get it right the first time, be deliberate, be consistent and be successful.
