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MassGIS Data: DEP Location Documentation Standards for GIS Data

DEP Location Documentation Standards for GIS Data

DEP has standards for location data. This is the documentation of that standard.

Table of Contents


Location Documentation Table Structure

L_BASEC / 3Base map type code
L_ACC_ESTI / 4Location accuracy estimate measurement
L_TYPEC / 4Location type code
L_METHC / 4Location method code
L_SRC_1C / 30Primary source material code
L_SRC_2C / 30Secondary source material code
L_SRC_3C / 30Tertiary source material code
L_DATEC / 8Date of automation

Description of Items

L_BASE (Location Base Map)
The standard MassGIS base map is the 1:5,000 digital orthophotography (DOQ).  Point data development at DEP should whenever possible conform to the 1:5,000 standard.  Since DEP has significant historical data developed at smaller scales (1:24,000 and 1:25,000), it is important that base scale be documented.

The L_BASE field contains a code that represents both the type of base map and/or the technique used for digitizing the location. (See Appendix A for a current set of DEP PDDS location base map codes).

L_ACC_EST (Location Accuracy Estimate)
Horizontal accuracy refers to the quantitative measurement of the deviation from a coordinate position to the actual position (on the ground) that the coordinate represents.  The DEP’s horizontal accuracy goal for point locations is +/-16.4 feet (approx. 5m).  This goal reflects the accuracy capabilities of the DEP’s GeoExplorer (GPS) receivers, which under optimal mapping conditions are capable of providing horizontal accuracy typically in the order of 2-5 meters.  The DEP’s horizontal accuracy goal exceeds the +/-25 meter (approx. 82ft) horizontal accuracy goal recommended by the EPA’s Locational Accuracy Task Force (LATF).  Like the EPA’s recommended accuracy goal (+/-25m), it is important to remember that DEP’s accuracy goal (+/-16.4 ft) is simply a goal and not a standard.  Most DEP point locations are estimated to be within +/-100 feet (30.5m), and the coarsest allowable horizontal accuracy for DEP production data is  +/-1,000 feet (305m).

The L_ACC_EST field contains an integer code representing the estimated horizontal accuracy of the location in feet, according to the data developer.  (See Appendix B for a current list of DEP PDDS location accuracy estimate codes.)

L_TYPE (Location Type)
The location type (L_TYPE) field contains a spatial reference code, indicating what the point represents.
(See Appendix C for supported location type codes.)

L_METH (Location Method)
The location method (L_METH) field contains an alphanumeric code defining the method used to locate the feature.  The location method is determined by the primary source used.
(See Appendix D for supported location method codes.)

L_SRC_1 (Primary Location Source)
The L_SRC_1 field contains a code indicating the primary source material used to locate the feature.  Relevant date information should be recorded in L_SRC_1_DATE.  (See Appendix E for supported location source codes.)

L_SRC_2 (Secondary Location Source)
The L_SRC_2 field contains a code that indicates the secondary source material used to locate the feature. Relevant date information should be recorded in L_SRC_1_DATE.  (See Appendix E for supported location source codes

L_SRC_3 (Tertiary Location Source)
The L_SRC_3 field contains a code that indicates any tertiary source material used to locate the feature. Relevant date information should be recorded in L_SRC_1_DATE.  (See Appendix E: for supported location source codes

L_DATE (Automation Date)
The L_DATE field contains the date the feature was located/automated in GIS.  The date of automation is automatically populated through the PDT.  When using an automation methodology other than the PDT, automation date should be entered as follows: 20010403 for April 3, 2001.  When editing locations outside of the PDT the L_DATE should be modified to reflect the date the point was last edited.

Appendix A:

L_BASE (Location Base Map) Codes

DOQDigital orthophoto base map (DOQ)
DTQUSGS digital topographic quadrangle (DTQ)
DVBDigital vector base (DVB) map
PTQUSGS paper topographic quadrangle (PTQ) base map or stable mylar overlay compiled from USGS topographic quad using traditional tablet digitizing technique
NANot applicable (NA), automation based on address match technique or Coordinate input from source such as external database or GPS.

Appendix B:

L_ACC_EST (Location Accuracy Estimate) Codes

16Estimated horizontal accuracy is 0 - +/-16 feet
100Estimated horizontal accuracy is +/-16 - +/-100 feet
500Estimated horizontal accuracy is +/-100 - +/-500 feet
1000Estimated horizontal accuracy is +/-500 - +/-1,000 feet
9999Estimated horizontal accuracy is greater than 1,000 feet
0Horizontal accuracy estimate unknown

Appendix C:

L_TYPE (Location Type) Codes

AAPerimeter of assigned areaPOLYGON
ABAdministrative buildingPOINT
AMAddress-matched locationPOINT
AMSAir monitoring stationPOINT
ARVAir Release VentPOINT
CACenter of site investigation activityPOINT
CB Center of a building footprint positively associated with the facility/sitePOINT
CB2 Center of a building footprint, NOT positively associated with the facility/sitePOINT
CFCenter of a facilityPOINT
CL Center of property lot or parcel associated with a facility/site addressPOINT
CSCenter of site or area of known contaminationPOINT
CT Center of individual tank or cluster of tanks (AST or UST)POINT
CWACenter of Waste (approximate/presumed)POINT
CWKCenter of Waste (known)POINT
ELEstimated locationPOINT
EWAExtent of Waste (approximate/presumed)POLYGON
EWKExtent of Waste (known)POLYGON
FRCenter of Firing Range (rod & gun clubs)POINT
FDApproximate location of front door or main entrance to a facility/sitePOINT
FDFFacility/Site Entrance (Freight)POINT
FDGFacility/Site Entrance (General)POINT
FDPFacility/Site Entrance (Personnel)POINT
FDUFront door or main entrance to a facility/site (Unspecified)POINT
FENFence-Line Visible on Source Map/ImagePOLYGON
GWWater supply wellPOINT
IWIrrigation wellPOINT
LAGLagoon or settling pondPOINT
MWMonitoring wellPOINT
PBParcel BoundaryPOLYGON
PDPoint of discharge (NPDES)POINT
PHPump house associated with PWS wellPOINT
PRPoint of release (Ch 21E)POINT
RESCenter of PWS reservoirPOINT
RWCenter of receiving water bodyPOINT
SASite Assigned areaPOLYGON
SC Source of contaminationPOINT
STEmissions stackPOINT
SWPWS surface water intakePOINT
TFCenter of trap field (rod & gun clubs)POINT
WMSWater monitoring station or sampling pointPOINT
WPPWS wellfield well point (TWF)POINT

Appendix D:

L_METH (Location Method) Codes

AM_1Address matched to number and street or parcel
AM_2Address matched to nearest intersection
AM_3Address matched to midpoint of street segment centerline
AM_4Address Matched to Zipcode Centroid
AM_5Address Matched to Town Centroid
DD_1Location snapped to point feature in an existing digital data source
DD_2Location snapped to the centroid of an existing area digital data source
GP_1GPS Survey Grade Carrier Phase Signal Data
GP_2GPS Coarse Acquisition Code:  DGPS (1-5 meter accuracy)
GP_3GPS Coarse Acquisition Code:  DGPS (sub-meter accuracy)
GP_4GPS Coarse Acquisition Code: Uncorrected, positions averaged
GP_5GPS Coarse Acquisition Code: Uncorrected, single position
GP_6GPS: Unspecified Device, DGPS Unknown
GR_1Digitized from Georeferenced map, registered with survey grade coordinates
GR_2Digitized from Georeferenced map, registered with DGPS (2-5 meter) coordinates
GR_3Digitized from Georeferenced map, registered using digital orthophoto
INInterpolation based on primary source material (L_SRC_1)
DDSInterpolation - Digital Map Source
MAPInterpolation - Map
MSSInterpolation - MSS
OTHInterpolation - Other
PHOInterpolation - Photo
SATInterpolation - Satellite
SPOTInterpolation - SPOT
TMInterpolation - TM
XY_1Coordinate pair derived from traditional survey techniques
XY_2Coordinate pair unverified or reported by regulated community, includes undocumented coordinate data

Appendix E:

L_SRC_(N)  (Location Source) Codes

Items                   Record Info

DB_BOHMassachusetts Board of Health
DB_EPICSDEP Environmental Protection Integrated Computer System
DB_EPAUnited States Environmental Protection Agency - System Unspecified
DB_DFSMassachusetts Department of Fire Services (DFS)
DB_DOEMassachusetts Department of Education
DB_SSEISDEP BWP Stationary Source Emission Inventory System
DB_RCRISEPA Resource Conservation and Recovery Information System
DB_WMADEP Water Management Act
DB_WPPDEP Water Permitting Program Database
DB_OTHOther Database Source
DD_21EDEP BWSC Chapter 21E Tier Classified Oil or Hazardous Materials datalayer
DD_BASMassGIS watershed/basin data
DD_ESRIESRI Data and Maps media
DD_FACDEP BWP Regulated Facilities datalayer
DD_GDTGeographic Data Technology (GDT) streets Geocoding datalayer
DD_GWPDEP Permitted Discharge to Groundwater datalayer
DD_HOSPMassGIS Hospitals and Emergency Room Facilities datalayer
DD_LUMassGIS Land Use datalayer
DD_MMRMassachusetts Military Reservation
DD_NPLUS EPA National Priority List datalayer
DD_OSMassGIS Open Space datalayer
DD_PAR      Digital Parcel Data
DD_PWSDEP Public Water Supply datalayer
DD_SCHLSchools datalayer
DD_SWDEP BWP Solid Waste Facilities datalayer
DD_SWAPContracted data developed through DEP SWAP
DD_TIGERUS Census Bureau TIGER Line Files
DD_USTDEP Underground Storage Tanks datalayer
DD_OTHOther Digital Data Source
MS_LMTQLocus map based on USGS topographic quadrangle map
MS_LMSTLocus map based on street information (ex. Street Atlas)
MS_LMOTLocus map other (ex. Trail map)
MS_MCPDEP MCP Site Scoring Map
MS_PIMDEP Pre-inspection Map
MS_SITEDetailed Site plan or map 
MS_SKCHHand sketched map
MS_SURVSurvey grade map of site derived from traditional survey techniques
MS_TAXTax assessment map
MS_USGSUSGS topographic quadrangle map
MS_WWWInternet map source (use L_COMM to record web URL)
MS_OTHOther Map Source
AP_CIRDWW Color Infrared photography 1:12,000
AP_DOQMassGIS 1:5,000 digital orthophotography
AP_GEGeneral Electric (GW) Project
AP_PCPictometry Community Oblique
AP_PNPictometry Neighborhood Oblique
DS_GPSGPS Data Sheet
FMSRField Measurement (tape and compass bearings)
KNOWLocated by DEP staff through knowledge gained in the course of their professional activities
TEXTTextual information
UNKSource Unknown
VERBVerbal information
WWWWebsite Information
EDEPSubmitted via eDEP Application, Source Unknown
APOther aerial photo source
MSSMulti Spectral Signature Image
SATOther Satellite Image
SPOTSPOT Corporation Image
SVSite visited for the purpose of field verification and/or site inspection
TMThematic Mapper Image

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