DEFINITION of IMPERVIOUS AREA

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DEFINITION of IMPERVIOUS AREA Classification of gravel driveways/roadways as impervious area is common to many stormwater utilities and is supported by a variety of state and federal sources. As you know, the Town,s bylaw language includes language that addresses this, as follows: "...lmpervious surfaces include, without limitation, roads, paved parking lots, rooftops, buildings or structures, sidewalks, driveways, and other surfaces which prevent or impede the natural infiltration of stormwater runoff which existed prior to development.,, Gravel driveways are manmade structures and clearly change the drainage patterns that existed prior to development. The Town's approach which includes gravel driveways as part ofthe lA delineation is consistent with the federal/state Municipal separate storm sewer system (M54) General permit, to which the Town is subject, which defines impervious surface as follows: "Any surface that prevents or significantly impedes the infiltration of water into the underlying soil. This can include but is not limited to: roads, driveways, parking areas and other areas created using non-porous material; buildings, rooftops, structures, artificial turfand compocted gravel or soif' (bold italics added). ln addition, at the state level, MassclS applied a similar definition when creating the lmpervious Surface data layer currently in use: "The lmpervious Surface raster layer represents impervious surfaces covering the Commonwealth of Massachusetts. The surfaces were extracted using semi-automated techniques...lmpervious surfaces are defined as: All constructed surfaces such as buildings, roads, parking lots, brick, asphalt, concrete. Also included are areas of mon- mode compocted soi, or materials such as mining or unpoved porking lots...,, (bold italics added). The description can be found in full here: https://docs.diEital.mass.sov/dataset/massqis-data-impervious-surface- 2OO5? ea=2.22877 t292.1129477 877.1547 L397 65-233944295.L537 538239.

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Impervious Calculation Worksheet
IMPERVIOUS CALCULATION WORKSHEET Instructions: 1. Calculate the area in square feet of all existing and proposed impervious surfaces on your lot within 300ft of the OHWM. 2. Divide the surface area of existing and proposed impervious surfaces on the portion of a lot or parcel that is within 300 feet of the Ordinary High Water Mark (OHWM) by the total area of that portion of the lot or parcel that is within 300 feet of the OHWM (the area shaded in gray below). 3. Multiply the result by 100. Impervious Surface SQ.FT. Driveway(s), [Concrete, Pavers, Gravel, etc.] Garage(s), Pads [Concrete, Pavers, Gravel, etc.] Walkway(s), [Concrete, Pavers, Gravel, etc.] House Patio(s), Pool(s), Pool Apro n(s) Outbuilding(s), Any Slab(s) Lean-to(s) Other Impervious Area(s), [Retaining Walls, Block, etc.] Other TOTAL IMPERVIOUS SURFACE ( ) ÷ ( )×(100)= Total SQ.FT. of TotalSQ.FT.of Impervious Surfaces Shoreland Lot Total % of (Within 300’ of the OHWM) (Within 300’ of the OHWM) Impervious Surface Note: “Impervious Surface” means an area that releases as runoff all or a majority of the precipitation that falls on it. “Impervious surface” excludes frozen soil but includes rooftops, sidewalks, driveways, parking lots, and streets unless specifically designed, constructed, and maintained to be pervious. Staff can make additional impervious determinations based upon site specific circumstances. This handout is intended to summarize the standards, not replace the actual ordinance. For more information refer to Chapter 16 St. Croix County Shoreland Overlay Districts Community Development 715-386-4680 St. Croix County Government Center 715-245-4250 Fax [email protected] 1101 Carmichael Road, Hudson, WI 54016 www.sccwi.gov PREPARE A PLOT PLAN / SKETCH OF YOUR PROPERTY SKETCH MUST INCLUDE ALL OF THE FOLLOWING: 1.
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Stormwater Permit Submittal Requirements
Public Works Department 104 W. Magnolia Street, Suite 109 Bellingham, WA 98225 (360) 778-7900 STORMWATER PERMIT SUBMITTAL REQUIREMENTS Most development within the City of Bellingham that involves disruption of soils, or construction of buildings, streets, parking lots, etc. requires the issuance of a Stormwater Permit. This packet contains material that will aid you in providing a complete application for this permit. Stormwater Permit requirements are based on either the amount of soil to be disrupted (grading, vegetation removal), or the amount of impervious surface that is created or replaced on a site (building footprint, concrete, asphalt or gravel parking, sidewalk, etc.). A Stormwater Site Plan consists of plan sheets showing all proposed Stormwater systems and facilities, Stormwater Pollution Prevention Plan (SWPPP), and if applicable, a Stormwater report by a licensed civil engineer. Please follow the steps on the worksheets to determine the level of stormwater management required for your project. Many applications will not need to use all information provided in this packet. If you need assistance in your determination, contact the Development section of the Public Works Dept. located at 104 W. Magnolia St., Suite 109 or call (360) 778-7900. STORMWATER MANAGEMENT REQUIREMENT CHECKLIST Provide the following information as part of your submittal: □ Impervious surface calculation (see next page) □ Stormwater management requirement determination □ Stormwater site plan and/or erosion control plan as stated on the applicable Requirements List I, II, or III □ Attach a copy of a General Construction Stormwater Pollution Prevention Plan (SWPPP) to Site Plan (see Page 7 of this packet) and erosion control details (see Page 8) IMPERVIOUS SURFACE CALCULATION Per Bellingham Municipal Code 15.42 Stormwater Management (http://www.codepublishing.com/WA/Bellingham/?Bellingham15/Bellingham1542.html), “Impervious surface” means a hard surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development.
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Impervious Vs. Pervious Pavement/Material
IMPERVIOUS VS. PERVIOUS PAVEMENT/ MATERIAL There are two primary types of pavement: pervious and impervious. Pervious pavement is designed to let water naturally seep through it and go down into the soil beneath. Impervious pavement does not allow water to seep through it. Instead, with impervious pavement, water runs off into storm drains that are lined along the road or paved surface at particular intervals. DISADVANTAGES OF IMPERVIOUS PAVEMENT: The number one contributor to urban flooding is impervious surface. Concrete and asphalt do not absorb water and instead create runoff from flash flooding from stormwater during rain events. Stormwater runoff floods streets then moves into homes and businesses creating extreme flood damage and safety hazards. Drainage systems for impervious surfaces can quickly get overcome and overwhelmed by heavy rain as they have limited inlets and storage capacity. THE BENEFITS OF PERVIOUS PAVEMENT • Promotes infiltration of stormwater • There are many pervious surface and paving material choices • Paver systems are easy to repair or replace • Slows stormwater runoff • Helps clean the stormwater through filtering it through the base material and soil • Beneficial to street trees as roots can have more access to air and water • Pavers enhance curbside appeal and increase property value • Groundwater recharge where soils and geologic conditions allow NOTE; ANY QUESTIONS CONTACT ROBERT LAWSON, ZONING OFFICER AT 908 259-3023 OR EMAIL: [email protected]. ALSO SEE THE FOLLOWING LINK: https://youtu.be/68F_TQtldrA .
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2017 Renton Surface Water Design Manual: Definitions
CITY OF RENTON SURFACE WATER DESIGN MANUAL DEFINITIONS Note: The following terms are provided for reference and use with this manual. They shall be superseded by any other definitions for these terms adopted by ordinance. Acceptable discharge point means an enclosed drainage system (i.e., pipe system, culvert, or tightline) or open drainage feature (e.g., ditch, channel, swale, stream, river, pond, lake, or wetland) where concentrated runoff can be discharged without creating a significant adverse impact. Adjustment means a department-approved variation in the application of the requirements of RMC 4-6-030 and this manual. Alkalinity means a measure of the acid neutralizing capacity of water; the ability of a solution to resist changes in pH by neutralizing acidic input. Alluvial soil means a soil found in valley bottoms that is generally fine-grained and often has a high seasonal water table. Anadromous fish means fish that live as adults in saltwater and migrate up freshwater streams and rivers for spawning. Applicant means a property owner or a public agency or public or private utility that owns a right-of-way or other easement or has been adjudicated the right to such an easement under RCW 8.12.090, or any person or entity designated or named in writing by the property or easement owner to be the applicant, in an application for a development proposal, permit, or approval. Appurtenances means machinery, appliances, or auxiliary structures attached to a main structure, but not considered an integral part thereof, for the purpose of enabling it to function. Aquatic area means any non-wetland water feature including all shorelines of the state, rivers, streams, marine waters, inland bodies of open water including lakes and ponds, reservoirs and conveyance systems and impoundments of these features if any portion of the feature is formed from a stream or wetland and if any stream or wetland contributing flows is not created solely as a consequence of stormwater pond construction.
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Quantification and Analysis of Impervious Surface Area In
remote sensing Article Quantification and Analysis of Impervious Surface Area in the Metropolitan Region of São Paulo, Brazil Fernando Kawakubo 1,* ,Rúbia Morato 1 , Marcos Martins 1, Guilherme Mataveli 1 , Pablo Nepomuceno 1 and Marcos Martines 2 1 Laboratory of Remote Sensing, Department of Geography, University of São Paulo, São Paulo, SP 13010-111, Brazil; [email protected] (R.M.); [email protected] (M.M.); [email protected] (G.M.); [email protected] (P.N.) 2 Department of Geography, Tourism and Humanities, São Carlos Federal University (UFSCar), Sorocaba, SP 13565-905, Brazil; [email protected] * Correspondence: [email protected]; Tel.: +55-11-3091-3723 Received: 9 March 2019; Accepted: 5 April 2019; Published: 19 April 2019 Abstract: The growing intensity of impervious surface area (ISA) is one of the most striking effects of urban growth. The expansion of ISA gives rise to a set of changes on the physical environment, impacting the quality of life of the human population as well as the dynamics of fauna and flora. Hence, due to its importance, the present study aimed to examine the ISA distribution in the Metropolitan Region of São Paulo (MRSP), Brazil, using satellite imagery from the Landsat-8 Operational Land Imager (OLI) instrument. In contrast to other investigations that primarily focus on the accuracy of the estimate, the proposal of this study is—besides generating a robust estimate—to perform an integrated analysis of the impervious-surface distribution at pixel scale with the variability present in different territorial units, namely municipalities, sub-prefecture and districts. The importance of this study is that it strengthens the use of information related to impervious cover in the territorial planning, providing elements for a better understanding and connection with other spatial attributes.
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Stormwater Faqs
Kitsap County Public Works Stormwater Division Stormwater FAQs What is stormwater runoff? Stormwater runoff is generated from rain and snowmelt that flows over land or impervious (hard) surfaces, such as paved or gravel streets, parking lots, and building rooftops. It does not soak into the ground. The runoff picks up pollutants, then carries them to our streams, lakes and Puget Sound. To protect these resources, communities, construction companies, and industries use stormwater best management practices to filter out pollutants and/or prevent pollution by controlling it at its source. What is an impervious surface? Impervious surfaces are non-vegetated surface areas that either slow down or keep water from soaking into the soil as it would under natural conditions (prior to development). Impervious surfaces include: Rooftops Walkways Patios Paved driveways Parking lots or storage areas Concrete or asphalt paving Gravel roads or driveways Packed earthen areas Oiled, macadam or other surfaces that impede the natural infiltration of stormwater. Lawns and other turf areas like sports fields can also act like impervious surfaces due to compaction. Title 12 definitions 12.08 Definitions How is the impervious surface measured? The County measures impervious surface using as-built drawings, aerial imagery and site assessment. GIS (Geographic Information System) is also used to compute impervious surface area. What does the stormwater program do? The Stormwater program protects people, property and natural resources by reducing flooding, managing stormwater runoff and treating stormwater pollution. When did the stormwater program begin? The Stormwater program was established in 1993 by the Kitsap County Board of Commissioners (Ordinance 156-1993) and was originally called the Surface and Stormwater Management Program.
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Surface Urban Heat Island in Shanghai, China: Examining
SURFACE URBAN HEAT ISLAND IN SHANGHAI, CHINA: EXAMINING THE RELATIONSHIP BETWEEN LAND SURFACE TEMPERATURE AND IMPERVIOUS SURFACE FRACTIONS DERIVED FROM LANDSAT ETM+ IMAGERY Z. Zhang*, M. Ji, J. Shu, Z. Deng, Y. Wu Key Lab of Geo-information Science for Ministry of Education, Dept. of Geography, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China – [email protected], [email protected], [email protected], [email protected], [email protected] Commission XXI, WG VIII/3 KEY WORDS: Land Surface Temperature, Impervious Surfaces, Linear Mixture Spectral Analysis, Urban Heat Islands, Shanghai ABSTRACT: This paper investigates the relationship between the surface urban heat islands (SUHI) and the percent impervious surface area (%ISA) in Shanghai, China. The %ISA was characterized from a Landsat-7 ETM+ multispectral dataset using the Linear Mixture Spectral Analysis (LMSA). Several critical steps being taken to derive %ISA were discussed, including atmospheric and geometric correction, water feature masking, endmember selection through the maximum noise fraction transformation, spectral unmixing for endmember fractions, and accuracy assessment. The resultant %ISA was qualitatively evaluated by visually comparing its spatial patterns to the landuse pattern of Shanghai. The spatial variability of land surface temperature (LST) to %ISA was evaluated and compared to the variability between LST and NDVI, a conventional factor for SUHI prediction. The results indicated a strong and significant correlation between LST and %ISA for the spectral data involved in the study and virtually no relationship at all between LST and NDVI. The strong LST to %ISA relationship suggested that it was exactly %ISA that accounted for a large share of the urban heat island problem in Shanghai.
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Accumulation of Moisture in Soil Under an Impervious Surface J
Accumulation of Moisture in Soil Under an Impervious Surface J. L. MICKLE, Associate Professor of Civil Engineering, and M. G. SPANGLER, Professor of Civil Engineering, Iowa State University The objective of this study was to compare the long-time ac cumulation of moisture in a soil subgrade beneath an imper vious surface with the estimated equilibrium moisture contents based on measurements of the moisture retention characteris tics of the soil and the elevation of the groundwater table. Mois ture accumulation due to the formation of ice was not considered. A theoretical approach, based on thermodynamics, was used to evaluate the free energy per unit mass of water in a soil water system in terms of component free energies. Thus, the effects of adsorptive and gravitational force fields, surface tension, pressure and dissolved materials were considered. The experimental investigation was conducted in two phases. The first phase involved the routine tasks of periodically de termining soil moisture contents, soil temperatures and water table elevations under a 150-foot square impervious surface constructed of alternate layers of asphalt roofing paper and asphalt cement. The second phase was conducted to determine the soil moisture retention characteristics, in the form of desorption curves, and other properties of a series of undis turbed soil samples taken from under, and adjacent to, the im pervious surface near the close of the field investigations. EXPERIMENTAL INVESTIGATION •THE field laboratory site was on the Iowa State University Experimental Farm at Ankeny, Iowa. The parcel selected for the investigation was on a gentle swell of un dulating, glaciated land.
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Sizing Stormwater Control Measures for Treatment, Retention, and Peak Management
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Stormwater Drainage System Service Charge Frequently Asked Questions
Stormwater Drainage System Service Charge Frequently Asked Questions General Information: As Broken Arrow continues to grow, more of our City which used to be open fields, wooded areas, and agricultural sites are now covered by homes, businesses, roads, and parking lots. Without these areas the stormwater is forced to find a creek, ditch, pond, or storm sewer line. Increases in impervious areas from development pose greater challenges to stormwater quality, stormwater maintenance, and floodplain management. On April 15, 2002, the Broken Arrow City Council passed an ordinance creating the new Stormwater Drainage System Service Charge for the purpose of providing a reliable, equitable, and efficient funding source for the City of Broken Arrow Stormwater Management Program. The system service charge became effective May 1, 2002, to all properties within the City Limits. What is the stormwater drainage system service charge? Why does the City of Broken Arrow need a stormwater drainage system service charge? What are the charges used for? What is stormwater runoff? Are other communities implementing stormwater drainage system service charges also? Is this another tax? How was the charge determined? What is an impervious surface? As a commercial property owner, whom do I call if I think there is an error in the charge to my property? Why are churches and other tax-exempt properties charged? What happens if I don’t pay my bill? I live in a duplex, what will I be charged? If I don’t have any drainage problems near my property and my property drains directly to the creek, why do I have to pay? Hasn’t the City always had creeks and storm sewers to maintain? Why are we being charged now? Will the City fix drainage problems that are on my property? My neighborhood has drainage problems.
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Summary of State Stormwater Standards
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