Does the Tool Really Work?
The U.S. Environmental Protection Agency (EPA) has released a National Stormwater Calculator that reportedly can determine the predevelopment hydrology for any location in the United States. According to EPA, the tool can also evaluate how different green infrastructure technologies may help to manage or prevent runoff at a particular site. But what do you think? AGC wants your feedback – can this new EPA tool really do all of these things?
EPA’s website states that the calculator is a desktop application that will estimate the annual amount of rainwater and frequency of runoff from a specific site. The model’s estimates are based, in part, on inputs supplied by the user such as percent of impervious surface, soil type, and sizing of green infrastructure. EPA plans to update the calculator by the end of 2013 to allow the user to link to several future climate scenarios. The agency maintains that the tool “is designed to be used by anyone interested in reducing runoff from a property.”
About one-third of states and many localities already restrict the volume/velocity of stormwater runoff leaving newly developed and re-developed sites via standards that require a certain amount of rainfall to be retained onsite or captured/treated before it’s released. At the federal level, EPA continues to work on a first-time “post-construction stormwater rule” (a.k.a. the National Stormwater Rulemaking) expected to require the construction of permanent, long-term stormwater discharge controls that soak up and infiltrate stormwater throughout the life of the completed roadway or building. EPA’s post-construction stormwater rule was due out (in proposed form) by June 10, per a legal settlement with the Chesapeake Bay Foundation, but it has been delayed indefinitely. The parties are now in a 60-day dispute resolution process to try agree to a new rulemaking timeline or possibly renew litigation over EPA’s clean water policies.
It remains to be seen whether or not EPA’s newly released calculator can help the regulated community meet local, state and soon-to-be-promulgated national stormwater retention-based performance requirements. AGC has received preliminary reports that the user may need a background in engineering and stormwater management in order to accurately input the requisite data into the tool. Similar technical expertise may be required to accurately understand and analyze the results. If you have the opportunity to try out the Stormwater Calculator, please email your feedback to AGC’s Senior Environmental Advisor Leah Pilconis at pilconisl@agc.org. Industry’s comments will help shape AGC’s response to EPA’s future stormwater initiatives. Thank you in advance – your input is always much appreciated.
The National Stormwater Calculator tool and User’s Guide (60 pages) are online – find them here.
For more information or with any questions, please do not hesitate to contact Leah Pilconis at pilconisl@agc.org.
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