DCGIS.MS4StormSewershedDissolvePly
Metadata also available as
Metadata:
- Identification_Information:
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- Citation:
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- Citation_Information:
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- Originator: District Department of the Environment
- Publication_Date: 20111105
- Title: DCGIS.MS4StormSewershedDissolvePly
- Geospatial_Data_Presentation_Form: vector digital data
- Online_Linkage:
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Server=10.1.11.144; Service=5151; User=dcgis; Version=SDE.DEFAULT
- Larger_Work_Citation:
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- Citation_Information:
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- Originator: DC GIS
- Title: DC Geographic Information System
- Geospatial_Data_Presentation_Form: vector digital data
- Description:
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- Abstract:
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District MS4 Sewershed drainage areas. The dataset contains locations and attributes of the drainage areas of MS4 outfalls created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies.
A database provided by WASA identified outfalls, drainage structures, and MS4 outfall locations.
All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters.
METADATA CONTENT IS IN PROCESS OF VALIDATION AND SUBJECT TO CHANGE.
- Purpose:
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This data is a requirement of the District's MS4 Permit. It is used for stormwater management in the District.
- Supplemental_Information:
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MS4 Sewershed Facts and Limitations:
The new MS4 Sewershed layer is a new iteration of existing MS4 sewersheds. Upon reviewing WASA and LimnoTech sewersheds, it was found that both layers depict single drainage systems per sewershed but the actual drainage area of each storm drainage system was not adequately depicted. This version of the MS4 sewershed is also based on contours but 2' contours were used and were available whereas a 1 meter contour was available before.
Other data layers used include both existing sewersheds, breaklines, elevation points, road edge, sidewalks, parking lots, alleys, WASA CSO, Sanitary, and MS4 sewer gravity mains, catch basins, manholes, NPDES outfalls, sewer outfalls, MS4 outfalls (04-06 GPS survey), and other relevant DC planimetric layers. Counter maps and plans were georeferenced and used as verification of existing sewer GIS data. Google Street View was used for field verification desktop side. Some examples include elevation changes, roof drainage direction and outlets of down spouts if visible.
The delineations depict the "headwaters" of each storm sewer system and include all surface areas that will drain to strormwater catch structures. Areas where storm water is transported by pipe network are also depicted. This results in polygons with thin elongated areas that appear to traverse over other sewershed polygons and or end up at an outfall. The areas where these thin elongated part(s) of a sewershed traversing through other sewershed(s) add to the area of its sewershed and also take away area from the sewershed that was traversed through.
Level of Accuracy:
This sewershed layer was created with reliance on the new 2 foot topographic contours. Adjustments to the delineations were done where man-made structures exist such as curb, buildings, walls, etc. that can divert the flow of surface water. Sometimes adjustments were also necessary as lot gradings are usually sloped away from buildings even when contours don't show it. Therefore certain locations the delineation may not follow contour exactly. This was verified by use of Google Street View to verify actual land surface and grading. It can be concluded that the accuracy of this data is much better than the 2 existing sewershed because of the availability and use of road edge, buildings, new technology (Google Street View) and updated data such as 2' contours.
Assumptions and Criteria:
1. Storm sewer GIS data are used to determine structure location. If structure location can be identified by ortho photo, the location visible in the ortho photo will be used if verifiable with Google Street View.
2. Delineations start at the outfall point determined by above step.
3. Delineated area depict pipe (water transport) from the outfall back up to the first storm inlet structure (area of the outfall pipe minimized but still able to show outfall pipe location and outfall)
4. Polygon boundaries of delineated areas are digitized perpendicular to contour lines to depict possible water flow direction. This is seen on roads where water from the centerline flows toward the catch basin due to road banking.
5. Solid walls, building foundations, or similar structures such as curbs and sold permanent barriers will divert the flow of water. (Verified by Google Street View)
6. Building roof (design) can alter flow of water with consideration of where downspouts from gutters outlets and direction they point.
7. Any pipe that daylights (outfall) is considered a storm system no matter whether it's 1 pipe or a pipe network
8. Areas that don't have GIS for storm infrastructure, contour, roads, buildings, orthophoto and Street View are used to estimate most likely storm drainage system routing to determine sewershed.
Data needing field verification:
2000 series outfall ids are ids given to outfalls that exist in WASA's outfall database or outfalls that was estimated to be existing. The WASA outfalls that did not have a location matched GPS outfall point were most likely to have been missed during the 2004-2006 GPS surveys. Once all 2000 series outfalls have been verified to either exist or not and have some more data attributes collected for them, then they can be determined if they meet the MS4 criteria and definition of being a MS4 outfall. Basically all drainage pipes that daylights are captured and assumed to be MS4 and have an outfall.
Impervious layer (MS4 Sewersheds Impervious):
This layer was created by overlaying the MS4 Sewershed over the Impervious Surface from DCGIS Central. The resulting modified impervious layer would also display the "perceived overlaps" because of the method the sewersheds were delineated. Those areas had to be manually reassigned to the correct sewershed. In the case of impervious surfaces, the location of the outfall was assumed to be non essential. Therefore, areas where another sewershed's outfall pipe crossed over can be reassigned back to the overlapped sewershed.
- Time_Period_of_Content:
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- Time_Period_Information:
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- Single_Date/Time:
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- Calendar_Date: 20111105
- Currentness_Reference: publication date
- Status:
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- Progress: Complete
- Maintenance_and_Update_Frequency: As needed
- Spatial_Domain:
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- Bounding_Coordinates:
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- West_Bounding_Coordinate: -77.114322
- East_Bounding_Coordinate: -76.909018
- North_Bounding_Coordinate: 38.994517
- South_Bounding_Coordinate: 38.804430
- Data_Set_G-Polygon:
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- Data_Set_G-Polygon_Outer_G-Ring:
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- G-Ring_Point:
- Keywords:
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- Theme:
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- Theme_Keyword_Thesaurus: none
- Theme_Keyword: Environment
- Theme_Keyword: storm
- Theme_Keyword: sewershed
- Theme_Keyword: rain
- Theme_Keyword: drainage area
- Place:
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- Place_Keyword: District of Columbia
- Place_Keyword: DC
- Place_Keyword: DC GIS
- Place_Keyword: DCGIS
- Use_Constraints:
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For data terms and conditions, go to <http://dc.gov/page/terms-and-conditions-use-district-data>
- Point_of_Contact:
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- Contact_Information:
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- Contact_Person_Primary:
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- Contact_Person: Julia Evans
- Contact_Organization: DDOE
- Contact_Position: Environmental Engineer
- Contact_Address:
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- Address_Type: mailing address
- Address: 1200 1st Street NE 5th Floor
- City: Washington
- State_or_Province: DC
- Postal_Code: 20002
- Country: USA
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<The facsimile telephone number, including area code, of the Contact Person.>
- Contact_Electronic_Mail_Address: <The Internet mail address of the Contact Person.>
- Hours_of_Service: <The hours of service of the Contact Person.>
- Data_Set_Credit: District Department of the Environment
- Native_Data_Set_Environment:
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Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.4000
- Data_Quality_Information:
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- Attribute_Accuracy:
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- Attribute_Accuracy_Report:
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Attributes wer derived with regard to field surveyed MS4 outfall locations in the MS4 permit, data from existing available GIS data and staff research of receiving waters.
- Logical_Consistency_Report: In process of validation of 2000 series outfalls
- Completeness_Report: Validated by source and/or responsible agency
- Positional_Accuracy:
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- Horizontal_Positional_Accuracy:
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- Horizontal_Positional_Accuracy_Report:
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Data acuracy is dependent upon contour, structures, storm drainage structures, and actual features on the land surface.
- Vertical_Positional_Accuracy:
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- Vertical_Positional_Accuracy_Report: N/A
- Lineage:
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- Source_Information:
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- Source_Citation:
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- Citation_Information:
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- Originator: District Department of the Environment
- Publication_Date: 2011
- Title: MS4 Storm Sewershed
- Online_Linkage: <http://ddoe.dc.gov>
- Type_of_Source_Media: audiocassette
- Source_Citation_Abbreviation: MS4 Storm Sewershed
- Source_Contribution: location and attribution
- Process_Step:
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- Process_Description:
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Boundaries were derived from contour, taking in to account any features that may impede or alter the flow of water, such as road edge, walls, buildings, and catch basins. Google street view was used in verifying locations of catch basins, roof drainage and downspout locations where applicable, and contour of land as actual field visits were not possible.
- Process_Date: 20111105
- Process_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: District Department of the Environment
- Contact_Address:
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- Address_Type: mailing and physical address
- Address: 200 I Street SE, 5th Floor
- Process_Step:
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- Process_Description: Metadata imported.
- Source_Used_Citation_Abbreviation: C:\temp\MS4StormSewerShedPly.xml
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- Address: 200 I Street SE, 5th Floor
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- Source_Used_Citation_Abbreviation: C:\GISHOME\Stormshed_metadata.xml
- Process_Date: 20110224
- Process_Time: 12104100
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- Contact_Information:
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- Contact_Address:
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- Address: 200 I Street SE, 5th Floor
- Process_Step:
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- Process_Description: Dataset copied.
- Source_Used_Citation_Abbreviation: \\DDOE-G7C8HF1\C\GISHOME\MS4SewershedEdit.mdb
- Process_Date: 20110322
- Process_Time: 12240000
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- Address: 200 I Street SE, 5th Floor
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- Process_Date: 20110324
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- Contact_Information:
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- Address: 200 I Street SE, 5th Floor
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- Process_Description: Dataset copied.
- Source_Used_Citation_Abbreviation: \\DDOE-G7C8HF1\C\GISHOME\updates_03312011.mdb
- Process_Date: 20110401
- Process_Time: 12343000
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- Contact_Information:
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- Contact_Address:
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- Address: 200 I Street SE, 5th Floor
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\\dcgisshare.dcgis.in.dc.gov\public\DDOE_SWMD\updates_03232011.mdb
- Process_Date: 20110401
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- Address: 200 I Street SE, 5th Floor
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- Process_Description: Metadata imported.
- Source_Used_Citation_Abbreviation: C:\temp\MS4StormSewershedDissolvePly.xml
- Process_Date: 20110405
- Process_Time: 17030400
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- Contact_Information:
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- Contact_Address:
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- Address: 200 I Street SE, 5th Floor
- Spatial_Data_Organization_Information:
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- Direct_Spatial_Reference_Method: Vector
- Point_and_Vector_Object_Information:
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- SDTS_Terms_Description:
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- SDTS_Point_and_Vector_Object_Type: G-polygon
- Point_and_Vector_Object_Count: 1
- Spatial_Reference_Information:
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- Horizontal_Coordinate_System_Definition:
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- Planar:
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- Grid_Coordinate_System:
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- Grid_Coordinate_System_Name: State Plane Coordinate System 1983
- State_Plane_Coordinate_System:
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- SPCS_Zone_Identifier: 1900
- Lambert_Conformal_Conic:
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- Standard_Parallel: 38.300000
- Standard_Parallel: 39.450000
- Longitude_of_Central_Meridian: -77.000000
- Latitude_of_Projection_Origin: 37.666667
- False_Easting: 400000.000000
- False_Northing: 0.000000
- Planar_Coordinate_Information:
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- Planar_Coordinate_Encoding_Method: coordinate pair
- Coordinate_Representation:
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- Abscissa_Resolution: 0.000063
- Ordinate_Resolution: 0.000063
- Planar_Distance_Units: meters
- Geodetic_Model:
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- Horizontal_Datum_Name: North American Datum of 1983
- Ellipsoid_Name: Geodetic Reference System 80
- Semi-major_Axis: 6378137.000000
- Denominator_of_Flattening_Ratio: 298.257222
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Explicit elevation coordinate included with horizontal coordinates
- Entity_and_Attribute_Information:
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- Detailed_Description:
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- Entity_Type_Label: DCGIS.MS4StormSewershedDissolvePly
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Sequential unique whole numbers that are automatically generated.
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- Contact_Organization: DC Office of the Chief Technology Officer
- Contact_Person: GIS Data Coordinator
- Contact_Address:
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- Address_Type: mailing and physical address
- Address: 200 I Street SE, 5th Floor
- City: Washington
- State_or_Province: DC
- Postal_Code: 20001
- Country: USA
- Contact_Facsimile_Telephone: (202) 727-5660
- Contact_Electronic_Mail_Address: [email protected]
- Hours_of_Service: 8:30 am - 5:30 pm
- Resource_Description: Downloadable Data
- Distribution_Liability:
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For data terms and conditions, go to <http://dc.gov/page/terms-and-conditions-use-district-data>
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- Digital_Form:
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- Metadata_Date: 20110405
- Metadata_Review_Date: <publication date - format dd/mm/yyyy>
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: D.C. Office of the Chief Technology Officer
- Contact_Person: GIS Data Coordinator
- Contact_Address:
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- Address_Type: mailing and physical address
- Address: 200 I Street SE, 5th Floor
- City: Washington
- State_or_Province: DC
- Postal_Code: 20001
- Country: USA
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REQUIRED: The telephone number by which individuals can speak to the organization or individual.
- Contact_Facsimile_Telephone: (202) 727-5660
- Contact_Electronic_Mail_Address: [email protected]
- Hours_of_Service: 8:30 am - 5 pm
- Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
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Generated by mp version 2.9.12 on Thu Jun 25 14:49:15 2015