Sewer Use Rules and Regulations - September 2003
Appendix B - GIS Protocol
The physical inspections required in the Administrative Consent Order are intended to provide four categories of information for inclusion on comprehensive sewer maps:
In order for a municipality/authority to create a newly updated, comprehensive sewer map of the sanitary sewers within the entire portion of its sewer system, directly or indirectly tributary to the Authority Sewer System, a municipality/authority may build upon the base sewer map that has been created by the Western Westmoreland Municipal Authority, or a comparable base sewer map. The comprehensive sewer map shall be submitted in Environmental Systems Research Institute (ESRI)-compatible format, and shall indicate, at a minimum, the location of the sewer lines, the direction of flow, the size of the sewer lines, the sewer line material, the locations where flows from other municipalities enter the sewer system, the field-verified location of manholes and the location of catch basins connected to the sewer system (identified by a comprehensive numbering or lettering system), the location of pump stations, force mains, and siphons, and the location of streams or drainage ways tributary to the sewers. These maps shall be created using Geographic Information System (GIS) mapping and verified using Global Positioning System (gps) ground monitoring or land surveying methods. The GIS mapping shall include the use of the specified attribute tables, data dictionary, etc., defined in this protocol. The maps must include, at a minimum, street names, municipal boundaries, and streams. Additionally, maps should include points of interconnection with other municipal or private sewer systems and any known points of sewer overflow including sanitary sewer overflows (SSOs), including manhole overflows and basement back-ups from the public sewer. The investigations conducted in preparing these maps shall include the location of any buried or lost manholes through metal detection or excavation, the identification of all unsewered residential areas within the sewer system and the associated estimated population of these unsewered residential areas.
Part 1: Technical Requirements
A. All significant sewer system structures such as manholes, regulating chambers, SSO outfalls, pump stations, or other appurtenances should be located to a minimum horizontal accuracy of three (3) feet. Coordinates should be recorded as "real coordinates" in State Plane Pennsylvania South NAD83 or WGS84. Vertical survey information should reference the NGVD29 datum. A spatial data projection file should be included in ESRI format noting the projection and datum used.
B. Structure locations may be determined using the following alternative methods:
C. In some geographic areas traditional surveying methods may be more productive than using GPS and, in some cases, a combination of above methods may be required. With regard to GPS data collection, additional information such as the number of readings used to define a point; standard deviation of values and the type of data correction should be recorded. The type of data correction can either be real time, post process or raw. The type of equipment and operator should also be included. Adherence to this minimum acceptable requirement will ensure that field verified data throughout the area are consistent.
D. For most of a municipal/authority sewer system, the precise elevations of manhole covers and manhole inverts are not required. However, surveyed manhole inverts, rim elevations, dam heights, overflow pipe elevations and slopes are required to a minimum vertical accuracy of 0.10 feet for regulator structures and SSO outfalls. Manhole inverts and rim elevations of manhole structures on trunks sewers shall also be surveyed to a minimum vertical accuracy of 0.10 feet when:
E. Digital data for basic sewer configuration, such as manhole locations, pipe sizes and materials, and manhole depths, will be entered into attribute tables within the 3RWWDP regional GIS system.
Part 2: GIS Attribute Data
Using existing municipal GIS mapping, computer drawn maps (CAD), or paper maps converted by heads up digitizing, standardized system base maps were created. All of these individual maps were used to build a comprehensive, though not comprehensively field verified, system-wide map.
This protocol will serve as a guide for the creation of an updated GIS sewer map. It is critical that all municipalities use standard field names and formats so the GIS data collected from each municipality/authority can be easily and cost-effectively integrated to form a complete system- wide map for the Authority service area.
The Data Dictionary defines the most. common fields and field values. While the Data Dictionary does not include all possible fields or field values, the primary aspects of mapping a sewer system are covered. The primary aspects that are covered in the dictionary relate to the physical description and location of the appurtenances and may not be complete enough for an evaluation. If additional fields must be added, for example the manhole inspection reports, then those fields or values should be described in the metadata, the documentation accompanying the GIS data.
Part 2.01: GIS Data Dictionary
Layer Name: Sewer Lines
Layer Type: Line
Feature: Sewer lines
Feature Definition: Sewer lines are identified as lines with line attributes stored in the Attribute Table. The following fields are in addition to those generated by ArcInfo, or respective software, and include field types, widths and in some cases domain, or acceptable, values. Please take note of unit measure. These files will be submitted in the State Plane coordinate system, Pennsylvania South, NAD 83. Metadata, as specified by the PaMagic recommended metadata standard, should also accompany the data.
Sewer Line Attribute Table
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