Draft reference grid cells for emergency response reconnaissance developed for use by the US Environmental Protection Agency. Grid cells are based on densification of the USGS Quarterquad (1:12,000 scale or 12K) grids for the continental United States, Alaska, Hawaii and Puerto Rico and are roughly equivalent to 1:6000 scalle (6K) quadrangles approximately 2 miles long on each side.
To provide a base reference grid system for the entire United States as a pre-staged resource for tracking and planning emergency response activities such as reconnaisance of debris after natural disasters, oil spill cleanups and planning of monitoring activities.
Developed by Weston Solutions for the United States Environmental Protection Agency. During an EPA response, 6K quad layer should be related to a look-up table (see example table in MS Access file included in the download file) tblMASTER_STATE_GRID_LU_4SDE100406) to update and map response status efforts. The Lookup table to be used in ArcSDE to relate many 6k quad grid cells to different geographies (State and County). 24k grids for Alaska and non-CONUS areas also included because their shapes boundaries do not exactly match with child 6k cells. Data elements of the lookup table: REC_NUM Number unique id - comes from unique record number created in parent grid layers. Initially named as 6k_ref, then Ref_6k Ref_ID Text Created by concatenating [STATE]-[Rec_Num]. Initially was named as Ref_6ks STATE Text State Name - there can be multiple records with same rec_num but different state name STATUS Text Current Grid Cell Status field. Default value is 'NA'. Other possible values are 'Open', 'Closed' and 'Active' LOCKSTATUS Text Indicates a locked value for record. Possible valuesare 'NA'(default), 'Open', 'Closed' and 'Active' LOCK_CMNT Text When LocakStatus field value is not NA then, a comment in this field indicates who implemented lockstatus, and why. QQQUAD_REF Number Value from Rec_num field of '24ksubquadbound.shp' or orginal SubQuad layer which was created only for gulf coast hurricane prone areas. QQQUADREFT Text Ref_ID value from '24ksubquadbound.shp' CONUS Yes/No identifies grid cells which will be part of final 6k quad layer but Continental US areas only SEL_12K Yes/No Identifies all cells that intersect with 12k layer. Initially named as 12k_sel
publication date
Unlimited use within EPA, limited use by other agencies while in draft form.. Final version will have no use constraints.
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quads6k_us.shp layer is extracted from a base layer 'vectorgrid.shp'. Vectorgrid layer extents are as follows: MinX: -179 MaxX: -64 MinY: 17 MaxY: 72 These extents cover all CONUS, Alaska, Hawaii, and Puerto Rico. Total number of records in vectorgrid.shp is approx. 6.5 million. Grid Cell Height - .03125 degrees Grid Cell width - .03125 degrees quads6k_us.shp: This layer is slightly different from 12k or 24k quad layers. It is created strictly as 1/4th scale of a 24k quad grid, which is 1/4th of 7.5 Degrees X 7.5 Degrees i.e. 0.03125 degrees X 0.03125 degrees. Actual Quad map differ from strictly square grid shape, in some areas outside of CONUS. Field Definitions for 6k Quad Layer: Label (Text) - Label value (Unique). Sel_12k (T/F): Identifies all cells that intersect with 12k layer. Initially named as 12k_sel QQQuad_ref (Number): Value from Rec_num field of '24ksubquadbound.shp' or orginal SubQuad layer which was created only for gulf coast hurricane prone areas. QQQuadRefT (Text): Ref_ID value from '24ksubquadbound.shp' Final_sel (T/F): identifies grid cells which will be part of final 6k quad layer. Conus (T/F): identifies grid cells which will be part of final 6k quad layer but Continental US areas only Rec_num (Number): Unique id for each 6k tile. Initially named as 6k_ref, then Ref_6k Link table tblMASTER_STATE_GRID_LU_4SDE - this is a lookup table for identifying all 6k grid tiles that belong to each single state. This table has many duplicate records with same value for ref_num. However ref_id value is unique. State: State that each tile belongs to. This field is found in link table Ref_ID (string): a concatenated string id [State]-[Ref_6k]. Initially named as Ref_6ks
14160 Dallas Parkway - Suite 850
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Metadata imported.
Dataset copied.
Assigned state abbreviation codes for grid cells whose centers that fell in coastal waters, large inland waters and for U.S. commonwealths, territories and associated areas such as Puerto Rico, US Virgin Islands and pacific islands and territories.
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Fields include unique identifiers and labeling information for use in linking to EPA response data and for referring to other spatial identifiers such as USGS Quarterquad identification, State, Zip Code and others.
Field Definitions for 6k Quad Layer: Field Name Type Length Description QQQUAD_REF Number 16 Value from Rec_num field of '24ksubquadbound.shp' or orginal SubQuad layer which was created only for gulf coast hurricane prone areas. QQQUADREFT Text 16 Ref_ID value from '24ksubquadbound.shp' FINAL_SEL Yes/No 1 Identifies grid cells which will be part of final 6k quad layer. CONUS Yes/No 1 identifies grid cells which will be part of final 6k quad layer but Continental US areas only REF_6K Number 16 Original unique id field. Identical to final unique id field, REC_NUM SEL_12K Yes/No 1 Identifies all cells that intersect with 12k (3.5 minute) quad layer. Initially named as 12k_sel REC_NUM Number 16 unique id - comes from unique record number created in parent grid layers. Initially named as 6k_ref, then Ref_6k Q24K_NAME Text 100 Name of parent 24k polygon - If available and if exists Q24K_ID Text 100 ID of parent 24k polygon -If available and if exists Q12K_ID Text 100 ID of parent 12k polygon - If available and if exists Q12K_NAME Text 100 Name of parent 12k polygon - If available and if exists SRCTHMNAME Text 100 name of parent GRID data shapefile. Current layer includes data from three shapefiles - Quads6k_us20060911.shp, Pacific_grid1sel.shp, and Pacific_grid2sel.shp NATGRID Text 254 US National Grid Coordinate of grid cell centerpoint LONG Number 16 Longitude in Decimal Degrees of center point of Gird Cell LONG_POS Number 16 Absolute value of longitude center point CTR_ZIP Text 10 Zip code of center point of grid cell CTR_ST Text 16 State abbreviation code for US State, commonwealth or territory either at center of grid cell or within related water features.
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