Gis ms4 permit presentation updated

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  • Modeling these events with Service RequestAllows tracking of labor Linking of digital file (stencil design, notification letter, pictures, etc.)Association with NPDES Phase II Project in Cityworks Project Manager
  • Using Service Requests to track:The issuance of citations related to erosion ordinance violationsTracking inspections at construction sitesAbility to link photos, documents or videosTrack time on inspectionsProvide comments on service request formCreate associated work order if necessaryDocumenting discharges from construction sitesLink documentation to service requestCreate associated work order if necessaryCreate custom inspections for construction related activities and inspections
  • - select open storm drains and stormwater inlets - create work orders for IDEP - search for all work orders associated with IDEP - Create event layer for representation of results - add event layer to view
  • Because single-family homes are the most common type of service, andthey have relatively uniform water use patterns, it makes sense tobase “equivalent per unit” water demands on them. Demands forother types of service, such as multifamily, industrial, andcommercial connections, often vary more widely.Using data for single-family residential demand allows for a morestatistically consistent and valid approach for determining theamount of water for a “typical” ERU. The ERU quantity isdetermined as either the mean, median, or mode of the demandfor the single-family residential customer group.After you establish a system’s ERU quantity, you can use it to determine the number of ERUsfor other types of service connections. The ERUs would be equivalent to what would be used bytypical single-family residences, if they were using the water. The result is an estimate of totalsystem service capability expressed as the number of ERUs the water system serves, or couldserve.
  • The Z-Score Test indicates how many standard deviations an observation is above or below the mean. Based upon the above calculations, it can refer to a process for normalizing a population which allows for comparison of observations other than normal distribution. Because standard deviation is measurement of the z-score, the outliers calculated by adding 3 standard deviations from the mean gives the same outliers as using a z-score of 3. Any observation with a z-score of 3 has a probability of .13% of being included in the population. Data skewed to one side and does not reflect typical residential property.The Modified Z-Score Test can be used in place of the Z-Score Test when a population is skewed to one side. It uses the MAD calculation (median absolute deviation) in place of the standard deviation of the population. Because the population is skewed by large impervious surfaces, the modified z-score test is used for its resilience to the outliers. With standard deviation, the distance from the mean are squared, so large deviations from the mean are heavily weighted thus making outliers weigh more heavily upon it. The modified z-score test may imply more outliers, but it is a more forceful estimator of scale than standard deviation, thus will perform better with skewed distributions.
  • Example ERU=261653,521 Sq Feet$3.75 per eru.
  • Gis ms4 permit presentation updated

    1. 1. Phase II StormwaterRequirements
    2. 2. What is the Phase II Rule?• Phase I and Phase II are EPA regulations which requireurbanized areas, classified as Municipal Separate StormSewer Systems (MS4), to minimize environmental pollutioncaused by stormwater runoff• Phase II resulted from the Clean Water Act (CWA) anduses NPDES permits to regulate urbanized areas withpopulation of 10,000 or greater (small MS4s)• Under Phase II, MS4 communities are required to adoptspecific practices regulating and controlling stormwaterrunoff within its municipal limits
    3. 3. What is the Phase II Goal?• Regulated small MS4s mustdevelop, implement, and enforce a stormwater management program designed toreduce the discharge of pollutants from thestormwater system to the State’s waterresources.
    4. 4. Required Program ComponentsSix program elements required by SCDEHC forPhase II compliance:• Public Education & Outreach• Public Participation & Involvement• Illicit Discharge Detection, Elimination &Enforcement• Construction Site Runoff Control & Enforcement• Post-Construction Runoff Control & Enforcement• Pollution Prevention & Good Housekeeping
    5. 5. SC Urbanized AreasAiken (City and County)Anderson (City andCounty)Arcadia LakesBerkeley CountyBurnettownCayceCharleston (City andCounty)City ViewColumbiaCowpensDarlington CountyDorchester CountyEdgefield CountyEdgefield CountyFlorence (City andCounty)Folly BeachForest AcresFort MillGeorgetown CountyGoose CreekHanahanHorry CountyIrmoIsle of PalmsLexington CountyLincolnvilleMount PleasantMyrtle BeachNorth AugustaNorth CharlestonPickens CountyPineridgeQuinbyRock HillSouth CongareeSpartanburg (City andCounty)SpringdaleSullivans IslandSummervilleSumter (City andCounty)Surfside BeachWest ColumbiaYork County… even more based on 2010 census data
    6. 6. Illicit Discharge Detection, Elimination & Enforcement• Illicit discharge is any discharge not composedentirely of stormwater entering the systemthrough direct or indirect connections• GIS Related BMPs:– Staff required to create system map showing all major outfalls withtopography– New permit cycle will focus on identification and mapping of entirestormwater system – includingditches, pipes, outfalls, manholes, catch basins, structural BMPs(ponds) and all major receiving waters– Staff required to detect and eliminate illicit discharges• Locate problem areas and find source• Remove & correct illicit discharge and illegal dumping• Document actions taken
    7. 7. • Polluted storm water runoff from construction sitesenter the system and discharge to the receivingstream• GIS related BMPs:– Staff required to review construction plans and check foruse of required BMPs to control erosion and sediment –tracking database– Staff required to conduct site inspections and enforcerequired control measures – tracking database• Develop procedures to inspect sites to ensure storm waterBMPs are in place• Establish procedures to enforce control measures such as issuewarnings, assess penalties, etc.Construction Site Runoff Control & Enforcement
    8. 8. Post - Construction Runoff Control & Enforcement• Recommended GIS related BMPs:– Database of completed construction sites and theirBMPs – a long term maintenance schedule will berequired for all structural BMPs in the next permit cycle– Inventory must be collected of all existing structuralBMPs for inclusion in inspection schedule. Needs to bemodified accordingly as new sites are developed.Reduce both pollutants and physical impactof new development resulting in landdisturbance greater than one acre
    9. 9. Pollution Prevention & Good Housekeeping• Reduce the amount of pollution being dischargedto water bodies from streets, parking lots, openspaces, and vehicle maintenance areas orresulting from inadequate maintenance of stormsewer systems• GIS related BMPs:– Staff must adopt pollution prevention program to reduce pollutantrunoff from all municipal operations by establishing maintenanceactivities, maintenance schedules and long-term inspectionprocedures to reduce floatables and other pollutants– Must establish procedures for the proper disposal of wasteremoved from municipal operations and encourage recycling anddocument activities
    10. 10. Asset Management
    11. 11. Asset Management
    12. 12. Asset Management
    13. 13. Stromwater RateStructure
    14. 14. Stormwater Fee - Considerations• All properties will be assessed a fee• Properties with impervious surface only will beassessed a fee• Commercial property impervious surfaces will beassessed while residential will be assessed at aflat rate• Exempt properties will be assessed a fee• Properties assessed fee once ground is broken orafter Certificate of Occupancy• Municipality/County have separate needs
    15. 15. Stormwater Fee Generator - Considerations• Condominiums (Residentialand Commercial)• Shared impervious surfaces(Parking/Drives)• Apartment Complex (MasterMeter)• Mobile Home Parks• Multiple contiguousproperties• Mixed use properties
    16. 16. Stormwater Fee Generator – Other Uses• Assessor– Valuation of property• Emergency Services– FEMA– DisasterRecovery/Mitigation– Response Planning• Planning– Land Use– Future Land Use• Stormwater– Credits– Modeling
    17. 17. Stormwater Fee Generator – Other UsesConsideration• Surface Type– Concrete– Asphalt– Compacted Soil– Gravel– Tile• Surface Use– Shelter– Parking– Pedestrian
    18. 18. Stormwater Fee Generator – Equivalent ResidentialUnit (ERU) or Equivalent Drainage Unit (EDU)• Single family homes are the most commonservice type as a basis for comparison• Residential unit allows for a more statisticallyconsistent and valid approach for determiningamount of water for typical ERU• Estimate of total system service capability as anumber or ERUs a system serves, or couldserve
    19. 19. Stormwater Fee Generator – Equivalent ResidentialUnit (ERU) or Equivalent Drainage Unit (EDU)Taken From The Entire Residential PopulationMedian 2,734.11Mean 4,087.98• Data does not follow anormal distribution• Using the middle 80%of the population• Outliers consist of thehighest and lowest 10%of area values.• Outliers = 1,196.59 ≥Values ≥ 7,047.47Middle 80% of ValuesMedian 2,734.11Mean 3,075.93
    20. 20. Stormwater Fee Generator – Equivalent ResidentialUnit (ERU) or Equivalent Drainage Unit (EDU)Z-ScoreMedian 2719.29Mean 3332.24• Z-Score Test– Outliers are consideredwhen ,Z>3Z= ABS (x-MEAN)Standard Deviation• Modified Z-Score– Outliers are consideredwhen ,Z>3.5Z= ABS (x-MEAN)Median{ABS(x-MEAN)}Modified Z-ScoreMedian 2554.97Mean 2987.82
    21. 21. Stormwater Fee Generator – Rate StructureConsiderations• Ranges of ERU– Can allow for inaccuracies inthe digitized impervioussurface– Graduated range• ERU +/-– Impervious surface accuracyis not questionableRange ERUERU RateRange ERU Range Total ERU FeeRsidential 0 $0.001 to 12 12 1 12 12 $45.0013 to 40 28 0.8 40 28 $84.0041 to 80 40 0.7 80 40 $105.0081 to 120 40 0.6 120 40 $90.00121 to 160 40 0.5 160 40 $75.00161 to 240 80 0.4 240 80 $120.00241 to 320 80 0.3 320 21 $23.63Over 321 0.2 0 $0.00Total Fee $542.63653,521 / 2,500 * 3.75 = $980.28
    22. 22. Stormwater Fee GeneratorGIS Centric Stormwater Fee GeneratorManages Impervious Surfaces for Each AccountGenerates Fees Based on Set Rate StructureAccount#Parcels Impervious•16007300•16007100•16007200AccountsCISUpdates CountyParcelsRelateToAccountsRelateToParcels•(City Maintained)Geoprocessing&Fee Calculation•Exported•Fees•Geodatabase
    23. 23. Stormwater Fee GeneratorStreamlines the Process of Managing AccountsSupports Various Integration Methods of Fees to Billing System
    24. 24. Stormwater Fee Generator
    25. 25. Questions?Greg ThackerGIS Project Managergthacker@bpbarber.com803-254-4400

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