IMPORT HIGH CONSEQUENCE AREAS

Summary

Import High Consequence Areas imports High Consequence Area (HCA) features into your specified Liquids HCA project geodatabase.

To learn more about the Liquids HCA Tool in general, please see Liquids HCA Tool Frequently Asked Questions.

To learn more about the structure of the Liquids HCA Tool project geodatabase, please see Liquids HCA Tool Data Dictionary.

Usage

Typically, HCA features are sourced primarily from the National Pipeline Mapping System (NPMS) website, which is maintained by the Pipeline and Hazardous Materials Safety Administration (PHMSA). However, the HCA features maintained in the NPMS should not be considered wholly sufficient to liquids HCA analysis; pipeline operators are ultimately responsible for identifying the HCAs that could be affected by a pipeline release, per the requirements of 49 CFR Part 195 Appendix C (I.)(A.). For this reason, the HCA features found in the NPMS should be considered a starting point; operators must have a procedure in place to review existing HCAs, and to identify potential new HCAs.

HCAs are categorized into a variety of types, per 49 CFR §195.450:

High Population Areas – High Population Area (HPA) means an urbanized area, as defined and delineated by the U.S. Census Bureau, that contains 50,000 or more people and has a population density of at least 1,000 people per square mile.
Other Populated Areas – Other Populated Area (OPA) means a place, as defined and delineated by the U.S. Census Bureau, that contains a concentrated population, such as an incorporated or unincorporated city, town, village, or other designated residential or commercial area.
Commercially Navigable Waterways – Commercial Navigable Waterway (CNW) means a waterway where a substantial likelihood of commercial navigation exists.
Unusually Sensitive Areas – Unusually Sensitive Areas (USAs) are defined in 49 CFR §195.6, and are further broken down into:
- USA Ecological Resources – An Ecological Resource (EC) is:
  - An area containing a critically imperiled species or ecological community.
  - A multi-species assemblage area.
  - A migratory water bird concentration area.
  - An area containing an imperiled species, threatened or endangered species, depleted marine mammal species, or an imperiled ecological community where the species or community is aquatic, aquatic dependent, or terrestrial with a limited range.
  - An area containing an imperiled species, threatened or endangered species, depleted marine mammal species, or imperiled ecological community where the species or community occurrence is considered to be one of the most viable, highest quality, or in the best condition, as identified by an element occurrence ranking (EORANK) of A (excellent quality) or B (good quality).
- USA Drinking Water Resources – A Drinking Water Resource (DW) is:
  - The water intake for a Community Water System (CWS) or a Non-transient Non-community Water System (NTNCWS) that obtains its water supply primarily from a surface water source and does not have an adequate alternative drinking water source.
  - The Source Water Protection Area (SWPA) for a CWS or a NTNCWS that obtains its water supply from a Class I or Class IIA aquifer and does not have an adequate alternative drinking water source. Where a state has not yet identified the SWPA, the Wellhead Protection Area (WHPA) will be used until the state has identified the SWPA.
  - The sole source aquifer recharge area where the sole source aquifer is a karst aquifer in nature.

The general public may download HPA, OPA, and CNW data from the NPMS website. However, due to its sensitive nature, download of USA data is restricted to pipeline operators and government officials.

HPAs, OPAs, and USAs are stored as polygonal features in the NPMS, whereas CNWs are stored as polyline features. The CNW polylines are derived from sources other than the NHDPlus High Resolution (HR) hydrography flowline data and may not be spatially consistent with the NHDPlus HR flowline data. Furthermore, given their width and depth, CNWs are almost always underlain by NHDPlus HR Area polygon features representing the true extent of the CNW hydrographic features. Because of this, the Liquids HCA Tool requires CNW features to be implemented as polygons, and all imported HCA features are thus stored in a single, polygonal feature class in the Liquids HCA project geodatabase. Import High Consequence Areas is designed to either import CNW features as polygons or to convert CNW polyline features into polygons on import (by buffering the input CNW polylines).In addition to importing your HCA features into your specified project geodatabase, Import High Consequence Areas creates HCA buffer polygons based on the buffer distance values stored in your project geodatabase global inputs table on a per intersection method and HCA type basis by centerline route. (See Enter Global Input Data and Import Global Input Data for details.) Buffer polygons for your HCA features are created by intersection method type for those HCA features that fall within your specified centerline, overland flow, and hydro trace intersection method search tolerance distance parameter values (relative to your centerline route features).

Import High Consequence Areas uses the following tool parameters:

Input Project Database – This parameter allows you to specify your Liquids HCA project file geodatabase. You created your project geodatabase with the Initialize Database By default, your input centerline route features and global inputs table are sourced from your Liquids HCA Project file geodatabase, and the output imported HCA features are written to your project file geodatabase.
Input Centerline Route Features – This parameter allows you to specify the centerline route features that will be used to help generate HCA buffers. You import centerline route features into your Liquids HCA project geodatabase using the Initialize Database tool. The default value for this parameter is the ROUTES feature class in your Liquids HCA project geodatabase. The tool looks for this feature class automatically; there is generally no need to alter the default parameter value.
Input Global Inputs Table – This parameter allows you to specify the global inputs table or table view to use in buffering HCAs. You populate the global inputs table using either the Import Global Input Data tool or the Enter Global Input Data The global inputs table stores data at the centerline route level regarding HCA buffer distance values on the basis of intersection method and HCA type. HCA buffer distances, when specified, are used to calculate indirect intersections of HCAs. The default value for this parameter is the ROUTES table in your Liquids HCA project geodatabase. The tool looks for this table automatically; there is generally no need to alter the default parameter value.
Input High Population Area (HPA) Features – This parameter allows you to select an HPA polygon feature layer for import into your Liquids HCA project geodatabase.
Input Other Populated Area (OPA) Features – This parameter allows you to select an OPA polygon feature layer for import into your Liquids HCA project geodatabase.
Input Ecological Unusually Sensitive Area (EC) Features – This parameter allows you to select an EC polygon feature layer for import into your Liquids HCA project geodatabase.
Input Drinking Water Unusually Sensitive Area (DW) Features – This parameter allows you to select a DW polygon feature layer for import into your Liquids HCA project geodatabase.
Input Commercially Navigable Waterway (CNW) Features – This parameter allows you to select either a polygon or polyline CNW feature layer for import into your Liquids HCA project geodatabase. If you select a polyline CNW layer, the following parameter is exposed:
- Commercially Navigable Waterway (CNW) Buffer Distance – This parameter allows you to specify a buffer distance in the linear units of your choice to use in converting your input polyline CNW features into polygons.
Output High Consequence Area Features – This parameter allows you specify the destination of the output imported HCA features. The default value is the HIGH_CONSEQUENCE_AREAS feature class in your specified Liquids HCA project geodatabase. If the feature class already exists, the tool appends output to the feature class. If not, the tool will create the feature class. There is generally no need to alter the default parameter value. Note that all attribution from your input HCA feature layers is preserved.
Input Centerline Search Tolerance – This parameter allows you to specify a search distance tolerance in the linear units of your choice from your input centerline route features for the purpose of selecting HCA features to create HCA buffers for use in determining indirect centerline HCA intersections. HCA features falling outside this search tolerance are not buffered. The default search tolerance value is 2 miles, meaning that only HCAs within 2 miles of your input centerline route features will be considered for indirect centerline HCA intersections.
Input Overland Flow Search Tolerance – This parameter allows you to specify a search distance tolerance in the linear units of your choice from your input centerline route features for the purpose of selecting HCA features to create HCA buffers for use in determining indirect overland flow HCA intersections. HCA features falling outside this search tolerance are not buffered. The default search tolerance value is 5 miles, meaning that only HCAs within 5 miles of your input centerline route features will be considered for indirect overland flow HCA intersections.
Input Hydro Trace Search Tolerance – This parameter allows you to specify a search distance tolerance in the linear units of your choice from your input centerline route features for the purpose of selecting HCA features to create HCA buffers for use in determining indirect hydro trace HCA intersections. HCA features falling outside this search tolerance are not buffered. The default search tolerance value is 25 miles, meaning that only HCAs within 25 miles of your input centerline route features will be considered for indirect hydro trace HCA intersections.

In a typical Liquids HCA Tool analysis workflow, Import High Consequence Areas is run after Import Global Input Data or Enter Global Input Data and before the Calculate Land Spill HCA Intersections and Calculate Hydro Trace HCA Intersections tools.

For visual reference on Liquids HCA Tool execution order, see Liquids HCA Tool Process Flow Diagrams.

Syntax

ImportHighConsequenceAreas _ (in_workspace, in_route_features, in_global_inputs_table, in_hpa_features, in_opa_features, in_ec_features, in_dw_features, in_cnw_features, out_hca_features, {in_cl_search_tol}, {in_of_search_tol}, {in_ht_search_tol})

Parameter	Explanation	Data Type
in_workspace	Dialog Reference Specify your input Liquids HCA Tool project geodatabase. The output from this tool is stored in this workspace. There is no Python reference for this parameter.	Workspace
in_route_features	Dialog Reference Specify your input pipeline centerline route features. There is no Python reference for this parameter.	Feature Layer
in_global_inputs_table	Dialog Reference Specify your input global inputs table. There is no Python reference for this parameter.	Table View
in_hpa_features	Dialog Reference Specify your input HPA features. There is no Python reference for this parameter	Feature Layer
in_opa_features	Dialog Reference Specify your input OPA features. There is no Python reference for this parameter.	Feature Layer
in_ec_features	Dialog Reference Specify your input ecological resource USA features. There is no Python reference for this parameter.	Feature Layer
in_dw_features	Dialog Reference Specify your input DW resource USA features. There is no Python reference for this parameter.	Feature Layer
in_cnw_features	Dialog Reference Specify your input CNW features. There is no Python reference for this parameter.	Feature Layer
in_cnw_buffer_dist	Dialog Reference Specify a buffer distance for use in converting your input polyline CNW features to polygons. There is no Python reference for this parameter.	Linear Unit
out_hca_features	Dialog Reference Specify the destination of your output imported HCA features. There is no Python reference for this parameter.	Feature Layer
in_cl_search_tol	Dialog Reference Specify the search distance tolerance from your input centerline route features to use in selecting HCA features for the creation of HCA buffers for use in determining indirect centerline HCA intersections. There is no Python reference for this parameter.	Linear Unit
in_of_search_tol	Dialog Reference Specify the search distance tolerance from your input centerline route features to use in selecting HCA features for the creation of HCA buffers for use in determining indirect overland flow HCA intersections. There is no Python reference for this parameter.	Linear Unit
in_ht_search_tol	Dialog Reference Specify the search distance tolerance from your input centerline route features to use in selecting HCA features for the creation of HCA buffers for use in determining indirect hydrographic trace HCA intersections. There is no Python reference for this parameter.	Linear Unit

Code sample

The following example demonstrates how to use Import High Consequence Areas in Python scripting:

import arcpy

arcpy.ImportToolbox(r”C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\Lib\site-packages\liquidshca\esri\toolboxes\LiquidsHCA.pyt”)

arcpy.env.workspace = r”C:\data\test.gdb”

in_workspace = r “C:\data\test.gdb”

route_features = r “C:\data\test.gdb\ROUTES”

global_input_tbl = r “C:\data\test.gdb\GLOBAL_INPUTS”

hpa_features = r “C:\data\HCA.gdb\HPA”

opa_features = r “C:\data\HCA.gdb\OPA”

ec_features = r “C:\data\HCA.gdb\USAEC”

dw_features = r “C:\data\HCA.gdb\USADW”

cnw_features = r “C:\data\HCA.gdb\CNW”

cnw_buff_dist = “250 Yards”

hca_features = r “C:\data\Test.gdb\HIGH_CONSEQUENCE_AREAS “

cl_hca_search_tol = “2 Miles”

of_hca_search_tol = “5 Miles”

ht_hca_search_tol = “25 Miles”

arcpy.liquidshca.ImportHighConsequenceAreas(in_workspace, route_features, global_input_tbl, hpa_features, opa_features, ec_features, dw_features, cnw_features, cnw_buff_dist, hca_features, cl_hca_search_tol, of_hca_search_tol, ht_hca_search_tol)

Environments

Current Workspace, Extent, Output Coordinate System, Geographic Transformations, Output has M values, M Resolution, M Tolerance, Output XY Domain, XY Resolution, XY Tolerance, Default Output Z Value, Output has Z values, Z Tolerance, Z Resolution, Scratch Workspace, Qualified Field Names, Auto Commit, Output M Domain, Output Z Domain

Licensing information

This tool requires a valid Liquids HCA Tool user license or subscription. Please see the Request License and Register License tool help topics for details on obtaining and registering a Gas HCA Tool software license.

Credits

Use limitations

There are no access and use limitations for this item.