Getting on the Map: Underground Utility Location And Municipalities By: Michael L. Gill, PE, RLS

Project:  Capstone project for Masters in GIS – Penn State University Dr Doug Miller – Academic Advisor Dr. Sunil K. Sinha – Technical Advisor  To investigate various methods to input municipal underground utility locations into a GIS.  Determine the accuracy of the input methods.  Begin to develop a Best Practices for getting legacy data into a GIS.

The Problem: How will we get this mapped accurately?

What we do not see - is the problem!

Every time we dig or need to dig, the problem re-occurs!

Problem Statement:  Municipal utility employees do not know where the facilities are located.  Municipal utility employees need to know where their facilities are located.  How can the legacy data be transformed into a modern GIS?

Extent of the problem:  In 2005, in Illinois alone 1.22 million “one call” requests Involved 1,700 separate utilities 7.94 million potential conflicts

Consequences of problem:  Disruption of utility service  Consumer inconvenience  Delays in construction  Added cost of construction  Added utility cost  Worker injury  Worker death

Results of Poor Mapping:

Current utility data location : Paper Maps CADD files Mental knowledge

GIS input methods: Heads-up digitizingScanning CADD Drawings CADD to GIS file conversion

Traditional location methods:  Soil borings  Test pits  Excavation Hand Machine  Potholes Vacuum Water jet

New location technologies:  Ground Penetrating Radar (GPR)  Magnetic field-based location systems  Buried markers  Acoustic-based plastic pipe locators  Could these technologies be directly outputted into a GIS? GPR unit & print out

It’s in – but how accurate is it? Can we safely dig where we need to? One-call system accuracy requirements range from 12 to 24 inches

Positional accuracy determination:  Get features into a GIS Calculate coordinates  Choose a random sample of features  Determine “true” position with a more accurate procedure Use GPS methodology  Complete a quantitative comparison of coordinates Do the math (avg, std dev, range, etc)  Understand how the accuracy affects the utility and its location procedures

Research Methods  Capturing Institutional Knowledge Operators digitize fire hydrant and sanitary sewer manhole locations into a GIS (ArcMap) Professional Survey Crew GPS’s same point locations (determine “true” location) Compute locations discrepancies (error distances) for various variables

Research Results -Albion Fire Hydrants – 6-in Base n10 Min1.8 Max23.2 Mean8.6 Std Dev7.7 GPS Unit - Trimble 5700 with base station Accuracy mm Base Map: 1m & 6-in Resolution Manholes - 6-in Base n26 Min0.2 Max23.9 Mean11.9 Std Dev1010.1

Research Results - Albion Fire Hydrants – 1m Base n2 Min7.2 Max8.6 Mean7.9 Std Dev4.8 Manholes – 1m Base n2 Min11.2 Max20.9 Mean16.1 Std Dev4.8 Fire Hydrants – All Data n12 Min1.8 Max23.2 Mean8.5 Std Dev7.1 Manholes – All Data n28 Min Mean12.2 Std Dev9.9

Research Results - Grayville Fire Hydrants – 6-in Base n5 Min2.2 Max9.8 Mean5.8 Std Dev2.6 GPS Unit - Trimble 5700 Rover Accuracy 1-3 m Base Map: 1m & 6-in Resolution Manholes – 6-in Base n14 Min4.3 Max68.2 Mean23.8 Std Dev19.0

Research Results - Grayville Fire Hydrants – 1m Base n16 Min6.3 Max52.8 Mean24.9 Std Dev13.6 Manholes - 1m Base n24 Min2.5 Max89.1 Mean24.9 Std Dev17.5 Fire Hydrants – All Data n21 Min2.2 Max52.8 Mean Manholes – All Data n38 Min2.5 Max89.1 Mean24.5 Std Dev18.1

Research Results - Lawrenceville Fire Hydrants n13 Min3.8 Max37.7 Mean10.2 Std Dev8.6 GPS Unit – Thales Mobile Mapper CE Accuracy Sub-meter Base Map: 1m Resolution Fire Hydrants – with Beacon Pack n13 Min0.1 Max37.6 Mean10.2 Std Dev8.6

Research Method - Georeferencing  This part not finished!

Breaking the cycle:  GPS both horizontal and vertical positions of underground utilities when: New construction takes place During maintenance operations Fixing breaks Anytime facility is exposed  Use data to update and improve the accuracy of existing maps.

Goals  Get all underground utilities mapped into a modern GIS system  Have mapped data accuracies to within “one- call” system tolerances  Capture and map vertical data as well as horizontal data

Proposed Location Capture Standards  Existing Systems GPS all valves, and meters (after digitizing)  Adjust digitized lines to match GPS points These surface features are directly above underground facilities

Proposed Location Capture Standards GPS all lines, fittings etc anytime they are exposed of maintenance, locates, repair, construction, erosion or any other reason  Adjust digitized lines to match GPS points

New Systems or Construction  Urban Capture both horizontal and vertical data to sub- foot location tolerances Capture location points at all fittings, valves, meters services, etc. Capture line locations at a maximum line spacing of 100 feet Keep GIS mapping up to date

New Systems or Construction  Rural Capture both horizontal and vertical data to sub- foot location tolerances Capture location points at all fittings, valves, meters services, etc. Capture line locations at maximum spacing of 500 feet Keep GIS mapping up to date

Idea to Ponder  Should location capture standards be a requirement the same as pipe material, pressures, etc?

Assumptions & Limitations:  Small sample set  Local in scope  GPS data is more accurate than input methods

Thank you! Questions?