Liquid HCA Tool Sequence Overview

This document provides an overview of the Liquids HCA (High Consequence Area) Tools workflow. This sequence is designed to guide users through database initialization, spill modeling (both overland and hydro trace), Azure cloud processing, and final could affect segments reporting.

Section 1: Project Setup

The foundation of the analysis begins with establishing a structured environment and defining the physical parameters of the pipeline.

1. Initialize Database

• Description: This is the mandatory first step. It creates a project file geodatabase (.gdb) at a specified location.
• Purpose: Pre-populates the database with specialized tables and schemas required for all subsequent analysis steps.

2a. Enter Global Input Data

• Description: A manual entry tool to populate pipeline operating conditions, product properties, and ambient/spatial constraints data needed to support the liquids high consequence area (HCA) analysis workflows.
• Usage: Best for single centerline routes or small-scale edits.

2b. Import Global Input Data (Optional)

• Description: Imports data into the global inputs table in the project geodatabase from an existing external tabular data source (e.g., a Microsoft Excel™ file). The external data table must contain the necessary pipeline operating conditions, product properties, ambient conditions, and spatial constraints data needed to support the liquids HCA analysis workflow.
• Usage: Recommended for projects involving multiple centerline routes to ensure efficiency and data consistency.

3. Import High Consequence Areas

• Description: Imports High Consequence Area (HCA) features into the project geodatabase.
• Purpose: Defines the “targets” that the spill modeling will eventually evaluate for impact.

Section 2: Create Release Points & Calculate Draindown

Before simulating where a spill goes, the tool must determine how much product is released.

4. Create Release Points

• Description: Creates release locations at a specified distance interval along the pipeline centerline route features on which you are performing release modeling.
• Purpose: These release point features serve as the “starting point” for subsequent plume transport and product fate simulations.

5. Calculate Draindown

• Description: A critical physics-based tool that calculates the volume of product that would exit the pipe at each release point.
• Factors Considered: Elevation profiles (local maxima/minima), shutdown time, and the location of block and check valves.
• Output: Determines which sections drain completely and which remain trapped.

Section 3: Land Spill (Azure Cloud Computation)

To handle the heavy computational load of overland plume simulations (GeoClaw), the toolset utilizes Microsoft Azure®.

6. Create Encrypted Azure Credential File

• Description: Generates a secure, password-protected file containing Azure Batch and Storage credentials.
• Security: Ensures sensitive cloud access keys are not stored in plain text.

7. Create GeoClaw Cases

• Description: Prepares “case folders” for every release point, including the necessary configuration files for the overland plume simulation.

8. Run Cases on Azure

• Description: Submits the prepared cases to the Azure Batch account for asynchronous, high-performance processing.

9. Monitor Azure Resources (Optional)

• Description: Provides real-time visibility into the status of the Azure Batch nodes and the progress of the active jobs.

10. Update GeoClaw Case Status

• Description: Syncs the status of Azure tasks back to the release point features.

11. Reactivate GeoClaw Cases (Optional)

• Description: A troubleshooting tool to restart tasks that failed due to system/cloud errors.

12. Download Cases from Azure

• Description: Downloads the finished GeoClaw simulation results from Azure Storage to the local working directory.

13. Create Multidimensional Raster Mosaic (Optional)

• Description: Consolidates the individual NetCDF output files into a single, manageable mosaic dataset for visualization.

Section 4: Hydro Trace Analysis

If a land spill reaches water, the analysis shifts to downstream transport.

14. NHDPlus High Resolution Data Download

• Description: Downloads NHDPlus High Resolution (HR) hydrography data from the NHDPlus HR data server and processes it to prepare it for use with the Hydro Trace tool.

15. Calculate Land Spill NHD Intersections

• Description: Calculates intersections between NetCDF release point plume simulations and NHDPlus HR hydrography features. The intersection point features output by this tool serve as the starting point locations for the downstream transport modeling performed by the Hydro Trace tool.
• Output: Creates starting points for hydrographic transport.

16. Hydro Trace

• Description: Utilizes NHDPlus High Resolution (HR) hydrography data to trace the downstream progress of a liquid release plume from the point where it first encounters a waterway.
• Purpose: Simulates how far and where a plume will travel within the river/stream network.

Section 5: Intersections & Reporting

The final phase determines which segments of the pipeline could affect HCAs.

17. Calculate Land Spill HCA Intersections

• Description: Performs High Consequence Area (HCA) intersection calculations on centerline route (release point) features and Land Spill overland flow plume transport analysis results.

18. Calculate Hydro Trace HCA Intersections

• Description: Performs High Consequence Area (HCA) intersection calculations on your Hydro Trace downstream plume transport features, outputting a table that tabulates HCA intersection data for each downstream transport plume.

19. Generate Could Affect Segments

• Description: Calculates “could affect” segment ranges on centerline route features based on information stored in the Liquids HCA project geodatabase’s HCA intersections table and stores the output in a could affect segments table in the Liquids HCA project geodatabase.

20. Generate Could Affect Segments Report

• Description: Creates a simple report in PDF file format from the “could affect” segments linear events table you created with the Generate Could Affect Segments tool.