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Converting Overhead to Underground

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Presentation on theme: "Converting Overhead to Underground"— Presentation transcript:

1 Converting Overhead to Underground
4/14/2017 Converting Overhead to Underground Modesto C. Rodriguez, P.E. T&D Engineer III (210) March 9, 2004 APPA Conference San Antonio, Texas

2 Objectives “Overhead to Underground” Conversion Program Background
Conversion Program Guidelines Projects Completed / In Work Project Selection Process Projects Selected for 2003

3 Objectives We have come a long way since 1993: What have we learned?
Joint Trench Issues Easements & Permits Trench Alignment Rivers to Cross? Bridge Attachments

4 Objectives Factors That Increase Project Costs Summary Questions

5 “Overhead to Underground”
Definition: Conversion of overhead electric distribution lines to underground operation IAW CPS standards, specifications, and accepted engineering practices. CPS utilizes dead front, loop feed, pad mounted transformers with load break switches in primary loop systems. CPS converts the electric system up to the customer’s meter loop. Distribution Voltages Included: KV L-L & 13.2KV L-L.

6 “Overhead to Underground”
When feeder sectionalizing is necessary, or for large multiple loads, CPS utilizes pad mounted, SF6 gas insulated, switchgear in underground primary loop systems.


8 BITTERS RD. CONVERSION 17,480 Ft Removal, Cost $ Million ($124.82/FT)

9 BITTERS RD. CONVERSION 17,480 Ft Removal, Cost $ Million ($124.82/FT)

10 BITTERS RD. CONVERSION 17,480 Ft Removal, Cost $ Million

29,875 FT Removal, Cost $1.82 Million

29,875 FT Removal, Cost $1.82 Million

29,875 FT Removal, Cost $1.82 Million

14 Conversion Program Background
On April 7, 1993, the CPS Board of Trustees directed staff to review design practices with the objective of modifying and incorporating aesthetic consideration (converting OH to UG) into it’s designs for electrical facilities. As a result of this request, numerous studies were conducted and results indicated it to be Cost Prohibitive to place facilities underground. Instead, in late 1993, CPS created a resolution amending the Capital Budget to include a budget to be known as the “Overhead Conversion Fund”.

15 Conversion Fund Background
The Funds are managed by the CPS General Accounting Department. Per resolution, the OCF budget is set at 1% of the electric revenue billed during the previous fiscal year to retail electric customers of CPS residing within the City, the Municipalities, and the Counties together with the balance of any amount budgeted in previous years not spent. Each of the 28 Municipalities and 8 Counties served by CPS has an appropriate fund allocation.

16 Conversion Fund Background

17 Conversion Program Guidelines
The OCF can be used for the following items: Convert Overhead Electric to Underground operation. Overhead facility modifications, i.e.. Relocate Overhead Electric. Modifications also include, replacing existing poles and cross-arms with aesthetic alternatives, steel poles.

18 Conversion Projects Completed / In Work
A total of 40 projects have been completed since the inception of Overhead Conversion Fund. 2 projects currently in construction. 2 projects are currently in design.

19 Project Selection Process
In 1997, COSA adopted a formal project selection process. Candidate Projects are gathered by COSA’s Capital Programs Division (CPD). CPD submits candidate projects to CPS for cost estimates. Total Cost = UG Cost + OH Removal - OH Material Salvage Value CPD evaluates and ranks projects. A Planning Commission reviews and selects projects to be implemented. CPD holds neighborhood association meetings to show the impact to the neighborhood.

20 Project Selection Process
Projects with favorable neighborhood association meetings remain on the list. City Council reviews and approves projects via a resolution authorizing the implementation of the project. CPS designs and plans the project utilizing CPS standards, specifications and accepted engineering practices. Based on construction workload, CPS may hire a contractor to complete the work.

21 Projects Selected in 2003/2004 12 projects were selected.
The estimated total cost for the 12 projects: $20.72 Million Status: To date only 2 of the 12 project have been released/ authorized by resolution. The conversion process began with a bang! However, currently, the other utilities are refusing to participate in 10 of the 12 projects for free.

22 We have come a long way since the inception of the program: What have we learned?

23 Joint Trench Issues During the design phase consideration should be given to other utilities. Other Utilities (CATV, Tele.) voluntarily elect to participate in an overhead conversion job. Establish a joint trench sharing agreement that describes the methodology for determining each utility’s share of the joint trench costs. Collect the full charges as determined by the agreement prior to commencing!

24 Easements & Permits Acquire Easements First!
Quickly follow-up with easement documents when given verbal permission to place lines & equipment by the property owner. Mandatory for placement of padmount transformers. Optional for services unless a service crosses over the property to serve a neighbor. Acquire permits or approvals as may be required to gain access to easements or properties owned by railroads, state highways and commissions as early as possible. Special permits may be required if the area is of archeological significance.

25 Trench Alignment Projects are usually selected in anticipation / coordination with Civic Improvement Projects. Select the most direct main trench alignment maintaining a consistent location within the street right of way keeping future CIPs in mind. Know where all existing and proposed facilities are located in effort to minimize conflicts with storm lines, inlets, water mains and sewer lines. Adjustments in elevation may be necessary. Avoid late fees associated with delays by managing the project closely while proactively resolving conflicts as quickly as possible.

26 Rivers to Cross? Bridge Attachments
Roosevelt / Grove St. Conversion

27 Factors That Increase Project Costs
Costs can vary greatly from project to project. Scope/Size of the project. Paved Vs. Unpaved areas. Soil Conditions: Dirt Vs. Rock. Standard Vs. Non-standard hours worked. Extra depth charges in effort to avoid conflicts with water mains, storm drains, storm drain inlets, fire hydrants and roadway elevation changes. Spare ducts to accommodate future circuit redundancy.

28 Factors That Increase Project Costs
Boring/Trenchless requirements under high traffic roadways, newly reconstructed streets, and railroads where open cuts are prohibited. Replacing OH switches and maintaining existing OH configurations utilizing padmount switchgear is costly. Submersible switchgear in Vaults. Dig ins.

29 Summary Overhead Conversion Fund is alive and well.
Mission accomplished. Future

30 Questions?

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