U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
|Minerals Materials Disposal Sites|
The Mineral Materials Disposal Sites (MMDS) shapefile has been created by a pair of Python scripts that extract records from BLM’s LR2000 database and generate shapefiles based on the legal land descriptions contained in those records. The extraction process is controlled by an SQL SELECT statement that selects active and pending records based on casetype. Case types included in the MMDS query include the following:
3604xx – Community pits
3605xx – Common use areas
361xxx – Mineral materials negotiated and sales
362xxx – Free use permits
The original shapefile has subsequently been dissolved on case-level attributes and projected to NAD83/UTM13N. The attribute table of the resulting shapefile contains the following fields:
We are typically able to create polygons for more than 90% of the records extracted from LR2000, but some records present problems for the script. Many of these error records result from a mismatch between the description of parcels in LR2000 and the geospatial database (GCDB) used as a reference. A common problem in this category is lot numbers in LR2000 that don’t have corresponding records in the GCDB database. Other problems include "free format" LR2000 records in which a nonstandard land description is specified; another is "metes and bounds" records that describe parcels in terms of a boundary based on direction and distance rather than a reference to the rectangular public land survey system (PLSS).
In order to point out parcels that are missing from the MMDS shapefile, we have provided an Excel spreadsheet that lists all of the problem records. There isn’t much that can be done about some problems, such as metes and bounds land descriptions, but others, like lot numbers that don’t exist in GCDB, can be resolved by editing errant LR2000 records and then requesting that a new shapefile be generated from the corrected LR2000 records. One of the reasons these scripts were developed is to facilitate the process of verifying the correctness and completeness of LR2000 records.
|Last updated: 12-27-2012|
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