LID Calculation Sheets & Maintenance Forms
- Rain Barrel
- Rain Garden
- Planter Box
- Tree Box
- Enhanced Shallow Swale
- Infiltration Trench
- Pocket Wetlands
- Pervious Pavement
What is a Rain Barrel? Rain barrels and cisterns not only help reduce stormwater runoff but can offer irrigation to landscapes throughout times of drought. Cisterns are larger than rain barrels and can be gravity fed or enhanced with a booster pump to deliver irrigation to larger areas. Rain barrels and cisterns are a good option if the soils on your property do not drain very well or if you are in a location where the groundwater is close to the surface.
Rain Barrel Calculation Sheet
Rain Barrel Maintenance Form
What is a Rain Garden? are Rain gardens bowl shaped depressions designed to collect and filter stormwater. Typical layers from bottom to top include small drainage stone, soil blended to maintain nutrients, a layer of mulch to assist with water filtration, and a vegetative layer intended to absorb water. Within the bioretention area planted vegetation facilitate treatment and remove pollutants from the collected runoff. Rain gardens are well suited to treat roof and pavement runoff. Rain gardens are a great management strategy for small drainage areas and can be used at locations where the water table is relatively high. They offer flexible retrofit capabilities and can be planned as an aesthetic feature bridging the gap between hardscapes and the natural hydrology of a site. Additionally, they offer habitat for pollinators and can be planted with vegetation that attracts butterflies.
Rain Garden Calculation Sheet
Rain Garden Maintenance Form
What is a Planter Box? Planter boxes are intended to be constructed in and around impervious areas. This approach is great for the perimeters of sidewalks and driveways, or along a house directly connected to roof gutters and other impervious areas. Planters next to foundations need to have an enclosed bottom with piping which leads away from the structure. Planter boxes provide a proactive method of reducing stormwater sheet flow and can easily enhance outdoor spaces. Plants use the water collected in the planter as it passes through the soil while excess water infiltrates into the ground below. Planters improve water quality by filtering out impurities and reducing the total volume of stormwater runoff.
Planter Box Calculation Sheet
Planter Box Maintenance Form
What is a Tree Box? Tree boxes can easily enhance outdoor spaces, while providing extra storage for stormwater. They enhance water quality by filtering out impurities and reducing the total volume of stormwater runoff. Typically, they consist of impermeable sides such as concrete depending on the location, the underlying soil type, and depth of SHGW. They are a great approach to areas with a lot of impervious area such as along the perimeters of sidewalks, driveways, or along other impervious areas. This application is desirable in most areas with well-drained soils (HSG A and B), as well as, soils that tend to drain slowly (HSG C and D). In arear with HSG C and D soils, the native soil is removed and replaced with well-draining soil.
Tree Box Calculation Sheet
Tree Box Maintenance Form
What is an Enhanced Shallow Swale? Enhanced shallow swales are geared more towards water quality versus water quantity. This approach is similar to methods employed for traditional stormwater management with one distinct difference. Instead of moving stormwater away form a site as fast as possible, this approach allows vegetative cells to fill to a predetermined height before the water is released to the next cell through a berm or weir. The area is typically planted with vegetation that varies in height to emulate a natural succession of variation among long grasses, plants that reach mid-height, and river stones dispersed throughout deeper rooted vegetation that can withstand flowing water and durations of complete submergence. Refer to Appendix A for plant recommendations. Enhanced shallow swales can be designed as dry swales or wet swales; existing soil conditions and the depth to the SHGW determine the design type that is best suited for your location.
Enhanced Shallow Swale Calculation Sheet
Enhanced Shallow Swale Maintenance Form
What is an Infiltration Trench? An infiltration trench runs horizontally under the ground. Infiltration trenches are best suited for areas where the available area for stormwater management is narrow and limited. Typical dimensions associated with infiltration trenches include widths less than 25 feet and depths ranging from 3 to 12 feet depending on the soil conditions, depth to ground water, and the required stormwater storage. The top layer of gravel must remain exposed and easily identifiable. Infiltration trenches work the best in areas with sandy soils. They provide a great opportunity to recharge the groundwater and provide increased storage capacity compared to some of the other LID SWMF options. If an infiltration trench is the preferred LID SWMF than a geotechnical investigation will be required, web based soil information is not adequate.
Infiltration Trench Calculation Sheet
Infiltration Trench Maintenance Form
What is a Pocket Wetland? Pocket wetlands are constructed shallow marsh systems designed to control stormwater volume and facilitate pollutant removal. Pocket wetlands effectively mimic the complex biological, chemical, and physical processes that take place in naturally formed wetlands.Pollutant removal in these systems occurs through the settling of larger solids and course organic material and by uptake by the aquatic vegetation. Additionally, they can act as temporary storage during extreme storm events and enhance the natural ecological variations that Northwest Florida has to offer. Increasing Pocket wetlands are designed with three distinct zones: a forebay immediately after the inlet, the wetland area, and a micropool immediately prior to the outfall, as wells, randomly dispersed throughout the system. The forebay and micropool allow for sediment control. They are similar in concept to a rain garden and enhanced shallow swale with the exception that they retain water and are the deepest portions of the pocket wetland.
Pocket Wetlands Calculation Sheet
Pocket Wetlands Maintenance Form
What are Pervious Pavers, Porous Concrete, and Geogrid Systems? Pervious pavers, porous concrete, and geo-grid systems are all semi-pervious pavement alternatives to traditional asphalt and concrete. This LID SWMF approach reduces the amount of stormwater runoff by allowing rainwater to infiltrate through it, where traditional pavement allows very little stormwater infiltration. Using this type of material can greatly increase infiltration in areas that would normally contribute to the volume of stormwater that would have to be retained and treated on site.
Pervious Pavement Calculation Sheet
Pervious Pavement Maintenance Form