If you have driven in Metro Atlanta lately, you surely know we have a LOT of people and not a lot of open space left anymore. For stormwater management, this has forced many developers to have to shift to underground best management features to free up valuable, useable space which your more standard detention ponds and other surface treatment features require. Unfortunately, going sub-terranean with your stormwater management practices does come with its own set of complications that are often times not properly considered. The first being, proper and routine inspection. With these devices being “out of sight” below grade, they often times go unnoticed and un-serviced for long periods of time, until an issue arises. With the frequent turnover of ownership of commercial properties or even more often residential HOA management boards, we often hear this feedback, “I had no idea we had an underground stormwater feature!” For an HOA, the best defense is knowing what you have and that starts with having and keeping a copy of the as-built design plans for the community. These design plans will show where all of the stormwater infrastructure is located and how it is designed to function.
Some other considerations/complications that are unique to underground stormwater management practices include:
- Confined Space. When dealing with the underground environment, confined space safety must become a consideration. Even a performing a simple annual inspection may require multiple people and special equipment such as air quality monitoring devices. Depending on the depth, accessing these features may also necessitate safety harness and descent devices for fall protection.
- Access for maintenance. While this is an issue with surface stormwater practices as well, underground features can take it to another level of complication. It is quite common for access into these features to be limited to just a standard manhole structure which is an average of 22-24 inches wide. While this is tight quarters even for a person it severely limits the type of equipment that can be utilized for routine maintenance and or repairs.
- Pre-Treatment Filters. Having a clogged outlet/spillway on a surface detention pond can be cause for concern. Having that occur under your parking deck or roadway, where many of these underground features are found, can be catastrophic. As such, underground stormwater features are often times combined with pre-treatment devices on the inlets which filter out the influx of bulk trash and debris which can clog an outlet or spillway. In the urban setting, these pre-treatment filters commonly have to be serviced annually.
Public education on the importance of proper stormwater management and more importantly operation and maintenance of underground systems in our experience is lacking. Increased public outreach on this subject is needed to ensure the long-term effectiveness of these features and ultimately the quality of our water. If you live “inside the perimeter” in Atlanta there is a good chance you community has an underground stormwater feature. Aquascape Environmental has the experience and the necessary qualifications in order to provide the necessary inspection of underground facility stormwater issues. Please contact us to assist you in identifying what you have so they can continue to function properly and remain compliant with the local regulatory community.
Georgia Stormwater Management Manual – Volume 2:Technical Handbook
