Charlotte-Mecklenburg Utilities Wastewater Data Conversion to Support Hydraulic Modeling

Transcription

1 Charlotte-Mecklenburg Utilities Wastewater Data Conversion to Support Hydraulic Modeling Rob Bailey CMU GIS Coordinator

2 Presentation Overview Regulatory Requirements Data Collection Approach Data Collection Field Work and QC Export to Hydraulic Model Lessons Learned Questions

3 Regulatory Requirements Capacity Assurance Program Ability to model wastewater flow from potential project site to treatment plant Wastewater Collection System Permit Map entire wastewater system Perform Collection System Inspection NCDENR Manhole inspections on annual basis Improve Work and Asset Management The ability to manage work and asset management using GIS and asset IDs

4 Data Collection Approach Planning Phase Developed data model to support regulatory and business requirements Decided to collect 10 and larger pipes as survey grade, 8 pipes as mapping grade and/or convert from as-builts Determined a mixed approach for data collection will have to be used to meet regulatory deadlines

5 Data Collection Approach Planning Phase Match converted data to survey grade data Subdivision Elevations at Localized Coordinate System Results all manhole elevations on NAVD88 Common Manhole Outfall Elevations at NAVD88

6 Data Collection Collect Attributes Used mapping grade GPS units to collect attributes Measured down to pipe elevations in manhole Collect Location Used survey grade GPS Trimble R8 Also used conventional survey equipment Joined attributes and location in office with common survey ID

7 Data Collection Data Collected with Low Level Photography Aerial photos with ¼ foot pixel resolution Control points collected to support requirements Manhole locations collected in stereo plotters Significantly less cost and faster than survey

8 Data Collection Survey Grade GPS Equipment Trimble R8 Model 3 with Trimble Access connected to TSC2 and NC Virtual Reference System Used GPS to collect manhole locations or set control Created a Feature Code Library for attributes

9 Conventional Survey Grade Equipment Data Collection Use Trimble robot or M3 conventional survey equipment where GPS will not initialize Able to move data collector seamlessly between GPS and conventional Export directly to Shapefile or Geodatabase XML

10 Field Work to Find or Verify Features Field Work and QC Verified elevations and depths to eliminate negative flow Manhole ID s were essential to perform field work

11 Field Work and QC Used CCTV to Find or Verify Features Paved over manholes Verified connectivity Found curves in pipe Discovered line breaks Manholes under buildings

12 Field Work and QC Other Benefits of Field Work Found significant line breaks or damage Identified immediate capacity issues for Engineering Old maps had incorrect pipe sizes Large pipes flowing into smaller pipes Collapsed pipe Direction bore damage Open channel flows Eliminated non-billed flow from wastewater system

13 Export to Hydraulic Model Getting Data Into Correct Format for Model Hydraulic Model Software Wallingford InfoWorks - now owned by MWH Soft Build Geometric Network with data Ensure features are snapped Temporarily remove loops and double out manholes Transfer attributes from manholes to pipes Use a script to transfer attributes from manholes to pipes Manually transfer data where pipes have no manhole at end

14 Export to Hydraulic Model Getting Data Into Correct Format for Model Elevations had to be correct Some areas had negative flow As corrections were made, have to make sure errors not pushed downstream Consistent and fully populated data Modelers wanted all attributes populated Must have consistent schema Work with datasets as large as possible

15 Lessons Learned Process to recover missing features Manholes not found Paved Over Buried Source data not always correct Go by what you find in the field Use System Maps as general reference or starting point As-builts or record drawings can also be incorrect ArcScene great for QC 3D view allows QC staff to quickly see errors in elevations

16 Lessons Learned Data Collection Attributes collected with mapping grade units did not always get transferred properly to survey grade locations Select more than one vendor to cover entire service area Use pilot for any change, even minor items Data model will never be static Survey Grade Data Survey grade equipment can be used to collect attributes Do not be intimidated by the need to collect elevation data

17 Questions? For Further Information Contact Rob Bailey CMU GIS Coordinator