There are considerations that need to be made for a stormwater management plan, such as the best locations for your stormwater management features. Let’s look now at some points that should be mulled over before stormwater management system plans are finalized.
Assessing the Site
Begin by making an assessment of your site. As you do this, identify the following:
- where water naturally flows and stands during, and after, a significant precipitation event
- where and how much water flows from all impervious surfaces such as parking lots, rooftops, roadways, etc.
- identify flow paths, slopes, low points (where water will stand), high points and discharge points of water on your site
- analyze vegetated areas – note native plants or areas you want to conserve and undesirable or invasive plants you want to eliminate
- note areas of bare ground
- map out all utilities on the site such as power, gas, water, communication, septic/sewer lines, etc.
Identify Potential Sites for Stormwater Features
After making a thorough site assessment, locations for LID features can better be determined to properly manage stormwater on your site. Factors to consider for the placement of LID features, such as permeable paving materials or a rain garden include:
- maintain ten feet minimum from trees to reduce the impact on the tree’s environment
- maintain ten feet minimum from building foundations unless a waterproof geomembrane such as AquaArmor is used
- avoid shady locations which can be difficult to establish vegetation and may take longer to dry out
- the site should have a gentle slope (i.e. a grade that is less than ten percent) for rain gardens and permeable paving
- the site of the LID feature should not be in conflict with other uses (e.g. play area)
- the site should not remain wet long after a precipitation event – indicates poor infiltration
- the site of the LID feature should pass a perc test
If you are adding LID features/strategies to your site, check with your local stormwater authorities (public works or environmental department) before starting to ensure that you meet local stormwater regulations.