Some of the terms used throughout the Rainscapes Rebates forms website


BacteriaSmall organisms which live in water. Excesses of bacteria are supplied to streams and rivers via stormwater runoff and are from sources such as pet and bird waste.
Bioretention SoilThis is the planting soil (media) used in rain gardens. It is a high sand mixture and also includes compost and low clay soils. The goal of this soil is to provide a sandy loam growing soil which is capable of rapidly absorbing and draining rainwater.
Canopy Tree A tree which is capable of being one of the tallest trees in the forest is a canopy tree. Canopy trees are those trees which mature at heights over 45 feet .
CisternWater harvesting in vessels larger than 250 gallons are considered to be "cisterns". These may be in a variety of shapes and from a variety of vendors. Cisterns may be above ground or below ground. All cisterns must have an overflow which provides for a place for excess water to go so that the foundation of the structure is not flooded. Cistern overflow must not be directed so that it flows onto adjacent property and creates a lot-to-lot drainage problem.
Conservation LandscapeA landscape converted from turf cover to a planting area comprised of at least 75% species native to the Cheasapeake Bay Watershed is considered to be a conservation landscape.
Disconnect downspoutThis means to redirect water from flowing to the street right of way to flow towards a surface which will absorb the water
DownspoutThe pipe which directs water from a gutter to the ground
Dry WellA dry well is a below ground trench or pit which is filled with drainage stone and captures water from downspouts or driveway and patio runoff. A perc. test is required and the drywell should be sized according to county dry well standards.
EcosystemAn ecosystem is comprised of many interrelated parts. And, similar to a watershed, can be looked at in a small scale context or a large scale context. There are several types of ecosystems. The dominant ecosystem type in Montgomery County prior to development was a forest ecosystem.
ESD/LIDESD is an acronym for Environmental Site Design. LID is an acronym for Low Impact Development. Both describe an approach to site development which attempts to restore or protect predevelopment hydrologic conditions, especially as it pertains to runoff and recharge of stormwater.
Green RoofA vegetated roof system which captures and stores rainwater. The typical extensive (flat) green roof that is 4" thick can hold up to 1" of rain water before water will runoff of the roof. Plants for green roofs must be extremely tolerant of dry and wet conditions.
Impervious surfaceThis is a surface which does not absorb water or allow it to pass on through. Typically this is a roof, driveway, patio or walk.
Infiltration rateThis refers to the speed at which water is absorbed by the ground. If soil can absorb water at a rate of .5 inches/hour or faster, it is considered to have good drainage.
Infiltration trenchAn infiltration trench is similar to a drywell but is a linear feature. Often they will be used to direct stormwater flow to anther facility but will allow some water to infiltrate rather than being fully conveyed to another site.
Native speciesThese are species which were found in the watershed area prior to European settlement. There are varying degrees of "nativeness" depending on which definition is followed. Named cultivars may or may not be native; most definitions of native exclude hybrid crosses of plants but may include named varieties which are part of natural variation in a population.
Non-native noxious invasives(NNIs)‘a plant that can, has, or is likely to spread into native flora or managed plants systems, develop self-sustaining populations, and become dominant and/or disruptive to those systems.’ Weed Science Society of America
Offsite DrainageStormwater that runs off of one property onto another is termed "offsite drainage". This can be a significant amount of additional water to be managed on a site.
Percent of roof areaThe area of the roof draining to an area divided by the total area of the roof , and then multiplied by 100 is called the percent of roof area. So, if 250 sf of a 1000 sf roof drains to a rain garden, 25% of the roof drains to the rain garden. A properly sized rain garden will control 25% of the roof runoff, up to a 2.7" rainfall event.
Percolation TestPercolation tests are tests which measure how fast water is absorbed by soil.
Permeable PavementPavement which is designed to infiltrate water through it rather than shed water off of it. The pavement may be designed to provide temporary runoff storage which then infiltrates or which is filtered and redirected to a stormdrain system. Permeable pavements may be designed for pedestrian or vehicular loads. The rebate program only rebates permeable interlocking concrete pavement at this time.
Rain BarrelWater harvesting in vessels smaller than 250 gallons are considered to be "rain barrels". These may be in a variety of shapes and from a variety of vendors. All rain barrels must have an overflow which provides for a place for excess water to go so that the foundation of the structure is not flooded.
Rain GardenGardens that are designed to handle a specific amount of rainwater runoff from impervious surfaces are termed "rain gardens". All rain gardens for rebate consideration must use bioretention soil, as specified by RainScapes. Rain gardens appear to the casual observer as a garden which is slightly sunken into the ground and will pond water for up to, but not more than, three days. Rain gardens provide several benefits: infiltration, wildlife habitat and beauty.
RebateThe county will pay property owners a set amount of money for implementing various voluntary projects on their properties for projects which reduce stormwater runoff and improve the water quality of runoff. The total value of all rebates per property cannot exceed $1200. Not all project types have the same rebate amount. All rebate projects must be voluntary and not to meet a permit requirement.
Roof areaRoof area is the area of the roof which is draining to the project area.
Rooftop areaThis is the area of the roof which is determined by measuring the length times the width of the roof.
Sand FilterA sand filter is like a dry well but filled with sand. The sand filter receives stormwater runoff and filters it before releasing it, usually through an underdrain, into the stormwater system. It is not meant to have any plants growing over the top of it as it captures and filters stormwater.
Saturated soilsSoil is like a sponge. Different soils have different abilities to absorb water. At some point, the soil will be unable to absorb more water and is "full" or called saturated.
Stormwater (management)Stormwater is water that falls on the ground (it appears usually as rain).
Sustainable StormwaterStrormwater which is managed for multiple environmental benefits is being termed "sustainable stormwater".
Test PitThe is the hole that is dug to perform a percolation test.
TN (Total Nitrogen) & TP (Total Phosphorus)This is a measure of the volume of nitrogen and phosphorus in runoff and stream water. The source of excesses of these nutrients is typically fertilizers and atmospheric deposition (emissions are captured in the water and delivered to the ground via rain).
TSS (total suspended solids) Suspended solids are particles of solid material, such as soil, trash, and other organic matter which is floating in runoff water. This material contributes to water quality problems. TSS is a measure of the volume of suspended solids; the county's goal is to reduce the volume of TSS in all of our waterways.
Water qualityThis is a measure of the health of the water to support ecosystems and to protect human health.
WatershedThe water shed is the land area which drains into a larger water body. Watersheds can be at a micro scale or large scale. Examples of watersheds are the Cheasapeake Bay Watershed and the Sligo Creek Watershed. The former is comprised of many smaller watersheds such as the Sligo Creek Watershed.