The City of Franklin, Indiana

A post-construction storm water management program is to manage storm water runoff from new development/redevelopment that drains into the MS4 and disturbs an acre or more of land surface, including projects less than an are that are part of a larger common plan of development or sale.  It is required to provide a mechanism to ensure long-term operation and maintenance of BMP's and that controls are in place to minimize water quality impacts. 

Franklin adopted and approved a Construction Site & Post-Construction Site Stormwater Control Ordinance in 2006 to implement and enforce the requirements of the ordinance for post-construction storm water structural and /or nonstructural BMP management.  That includes operational and maintenance measures as well as facilitating water quality measures. 

Why the Concern?

Increased impervious surface associated with development will increase storm water volume and degrade water quality, which can harm lakes, rivers, streams, and coastal areas.  The best way to mitigate storm water impacts from new developments or redevelopment is to use practices to treat, store, and infiltrate runoff onsite before it can affect waterbodies downstream.  Innovative site designs that reduce impervious surface and smaller-scale low impact development practices dispersed throughout a site are excellent ways to achieve the goals of reducing flows and improving water quality. 

 

Green Infrastructure  

Green infrastructure is an approach that communities can choose to maintain healthy waters, provide multiple environmental benefits and support sustainable communities.  Unlike single-purpose gray storm water infrastructure, which uses pipes to dispose of rainwater, green infrastructure uses vegetation and soil to manage rainwater where it falls.  By weaving natural processes into the built environment, green infrastructure provides not only storm water management, but also flood mitigation, air quality management, and much more. 

At a time when so much of our infrastructure is in need of replacement or repair and so few communities can foot the bill, we need resilient and affordable solutions that meet many objectives at once. Green infrastructure is one solution.

What is LID?

LID or Low Impact Development is an approach to land development (or re-development) that works with nature to manage storm water as close to its source as possible.  LID employs principles such as preserving and/or recreating natural landscape features, minimizing effective imperviousness to create functional site drainage that treats storm water as a resource rather than just runoff.  There are many practices used to adhere to these principles such as bio-retention facilities, rain gardens, vegetated rooftops, rain barrels, and permeable pavements. By implementing LID practices, water can be managed in a way that reduces the impact of built-up areas promoting the natural movement of water within an ecosystem or watershed.  LID can maintain or restore a watershed's hydrologic and ecological functions.  LID has been characterized as a sustainable storm water practice by the Water Environment Research Foundation and others.  LID can be applied to new development, redevelopment, or as retrofits to existing development.  LID has been adapted to a range of land uses from high density ultra-urban settings to low density development.


Rain Garden Animation


Click here for more information about Rain Gardens.
Rain Gardens - University of Connecticut

 

How Do Trees Reduce and Remove Pollutants form Storm Water Runoff?

Trees and forests improve stream quality and watershed health primarily by decreasing the amount of storm water runoff and pollutants that reaches our local waters.  Trees reduce storm water runoff by capturing and storing rainfall in the canopy and releasing water into the atmosphere through evapotranspiration.  Additionally, tree roots and leaf litter create soil conditions that promote infiltration of rainwater into the soil.  This helps to replenish our groundwater supply and maintain stream flow during dry periods. 

The presence of trees also helps to slow down and temporarily store runoff, which further promotes infiltration, and decreases flooding and erosion downstream.   Trees reduce pollutants by taking up nutrients and other pollutants form soils and water through their roots, and by transforming pollutants into less harmful substances.  In general, trees are most effective at reducing runoff from smaller, more frequent storms.  The Center for Urban Forest Research, Pacific Northwest Research Station, USDA Forest Service provides a fact sheet on the use of trees to reduce storm water runoff.  Along with the storm water benefits, trees provide a host of other benefits such as improved air quality, reduced air temperatures in summer, reduced heating and cooling cost, increased property values, habitat for wildlife, and recreation and aesthetic value.

Click here for more information about trees.
Working Trees for Water Quality

Watershed Forestry Resource Guide

The Role of Urban Trees in Stormwater Management