A surface dry well (micro-infiltration area), is a small trench filled with stone that collects rainwater from paved surfaces such as driveways and allows it to absorb into the surrounding soil.
A buried dry well is a small underground pit filled with stone that collects rainwater from roof gutters and allows it to absorb into the surrounding soil. Underground piping connects the dry well to the roof downspout.
Types of Strom Water Mangement Facilities
Grass Drainage Swales
A grass drainage swale is an open channel that collects water from hard surfaces and allows it to percolate into the ground, reducing the amount of runoff leaving the road or property. .
Intensive roofs are thicker, heavier, and are designed to support trees and larger shrubs.
Extensive green roofs are typically lighter and thinner, and are designed to support plants like sedum.
A green roof is a rooftop partially or completely covered with a specifically designed soil and vegetation system. Green roofs create living gardens on top of buildings and structures that help to capture rainfall and reduce stormwater runoff.
Nonstructural Drainage Practices
Common non-structural drainage practices include directing rain water (stormwater) from your roof gutters and driveways to nearby vegetated areas where it can soak into the ground.
Wet and Dry Ponds
A pond is a type of stormwater management facility designed to collect rainwater and pollutants and prevent downstream flooding.Wet ponds always have a pool of water.Dry ponds only have water after rain.Ponds have an embankment (called a dam) to hold back water that is entering the pond. Most ponds located throughout Montgomery County are stormwater management ponds, even ones that are community amenities.
Porous (Permeable) Pavement
Permeable pavement is built with materials that let water pass through. Replacement of traditional concrete or asphalt driveways with permeable pavement allows rainwater to naturally filter through the ground and reduces stormwater runoff. Permeable pavement provides a strong, solid surface that can be installed on driveways, walkways, and patios and can also serve as attractive landscaping features, raising property values.
Rain Barrels & Cisterns
Rain barrels and cisterns collect and temporarily store rainwater from roofs. This water can be used to water gardens, lawns, and trees. Rainwater enters them from gutters and downspouts and there is an outlet that can be connected to a garden hose. When they overflow, excess water is directed away from the building to a location on the property where it can soak into the ground.
Rain Gardens, Bioswales & Bioretentions
Rain gardens are saucer shaped gardens that water flows into that are planted with grasses, flowers, shrubs, and sometimes small trees.
Bioretention gardens are often used interchangeably with rain gardens. The one main difference is that bioretentions have underneath drainage, while rain gardens depend on the soil for proper drainage.
A bioswale is similar to a bioretention area in the way it is designed with layers of vegetation, soil and a perforated pipe within the bottom stone layer.
A sand filter is a type of stormwater management facility designed to filter rainwater through sand to remove pollutants. Filters are typically a depression in the ground filled with sand that helps to manage polluted or excess rainwater.
Underground Filtering Facilities
Proprietary underground filtering facilities remove pollutants from stormwater runoff by allowing it to flow through a filtration system. These systems are made by various manufacturers and have special filter cartridges to remove pollutants.
Underground Flow Splitter
A flow splitter is a stormwater structure that divides stormwater runoff between multiple stormwater facilities or between a stormwater facility and an offsite storm drain system. Flow splitters are located in residential neighborhoods and around commercial businesses.
Underground Hydrodynamic Separators
Hydrodynamic separators remove oil, grease, trash, and sediment from stormwater runoff. These underground structures include oil and grit separators and proprietary hydrodynamic separators. Underground hydrodynamic separators are commonly located under parking lots at commercial sites or multi-family residential sites (condominium, apartments, etc.).
Underground Sand Filter
An underground sand filter is a type of stormwater management facility designed to filter rainwater through sand to remove pollutants. Sand filters can be located on the ground surface or underground.
Underground Storage Structures
Underground storage structures are underground pipes or vaults that are typically used to store stormwater. Underground structures and vaults are used for stormwater storage where there is not enough space for an aboveground facility.