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WORLAND PIPELINE PROJECT

LEVEL II FEASIBILITY STUDY

EXECUTIVE SUMMARY

DECEMBER, 1997

SUBMITTED TO

WYOMING WATER DEVELOPMENT COMMISSION

Prepared by

FOR S G R E N ASSOCIATES I INC.

849 Front Street, Suite 201 Evanston, WY 82930

(307) 789-6735

TABLE OF CONTENTS WORLAND PIPELINE LEVEL II STUDY

EXECUTIVE SUMMARY

1.0 PROJECT OVERVIEW AND HISTORY

1.1 CONTRACT AUTHORIZATION

1.2 STUDY ISSUES AND OBJECTIVES

1.3 PIPELINE FAILURE MECHANISM

1.4 RECOMMENDED "IMMEDIATE NEEDS"

1.4.1 Automated Shut-off Valves at Well Head 1.42 SCADA System 1.4.3 Stored Repair Materials

1.5 ECONOMIC DATA

1.5.1 Recommended Project Cost Estimate 1.5.2 Probable Project Financing 1.5.3 Project User Rate Impact

1.6 WHAT NEXT?

FIGURES

1.1 Town of Worland - Location Map

TABLES

1.1 Worland Pipeline SCADA System 1.2 Worland Pipeline - Minimum Suggest Repair Materials On-Hand 1.3 Worland Pipeline - Recommended Immediate Needs - 'N'NDC Eligible Costs

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PROJECT LOCATION MAP

.. FIGURE: 1. 1 ~--------------------~ ~ftj7~.N--------------------~

WORLAND PIPELINE LEVEL II STUDY EXECUTIVE SUMMARY

1.0 PROJECT OVERVIEW & HISTORY

The community of Worland receives its domestic water supply from two artesian wells located approximately 20 miles away, near Bonanza. The Two wells are situated approximately 1 mile apart and are connected to a common juncture point through 6600 feet of 16-inch class 200 AC transmission piping. From that point, the water is conveyed to the city through 75,900 feet of 24-inch diameter and 17,000 feet of 20-inch diameter AC pipe respectively. The City of Worland is wholly dependent on this single transmission pipeline for their water supply. Even under normal conditions, this presents a concern due to possible catastrophic events (earthquakes, etc.). This concern is magnified by the city's experience(s) with line breakages and resulting questions relative to the integrity of the pipeline.

A model of the Worland supply and conveyance system located in Worland's public works building documents 32 leaks which have occurred in the transmission line since its construction. It is our understanding based on discussions with city staff the majority of these leaks occurred in conjunction with or shortly after construction.

In November of 1996, a pipeline leak surfaced in a high pressure section of line near the Sand Creek Crossing. This leak appears to be associated with a joint/gasket failure. The resulting jet of water wore a hole through the 3-inch thick pipe wall. Such external "sandblasting" is not uncommon and has been seen on many other similar AC pipe joint failures by members of the Forsgren project team. The leaking section of line was subsequently isolated and the section of pipe was replaced by the city.

Twenty-two days later on December 27th, a major line break occurred approximately 400 feet upstream of the Sand Creek leak. The result was the creation of a washout approximately 150 feet long, 60 feet wide, and 20 feet deep, along with the associated loss of pipe. City crews and contractors spent nearly a week filing the hole and replacing the pipe. During this period, drinking water for the city was hauled by truck from the Ten Sleep water system. Initial repairs were completed and the line was recharged on January 3rd of this year. Unfortunately, the pipeline once again failed at the same location prior to completion of the refilling process. The city was then faced with the frightening reality of having no repair pipe available, industries that had already been shut down for a week, and virtually no water in storage. Given the limited options available, and the high risks associated with continued water outages, a plan was quickly formulated to place the line back into service. Emergency repairs were completed on the second break within 24 hours.

The direct cost of this unfortunate experience is estimated to be in excess of $350,000 which includes the replacement of the 6-inch and adjacent piping, as well as about $80,000 for hauling water during the crises. None the less, the city was fortunate that the social and economic costs associates with the break were not even more severe. Such costs could have included the inability to fight fires, system contamination associated with inadequate supply and low system pressures, or even loss of life. This experience illustrates that the Worland transmission pipeline is literally a

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lifeline to the community. There are obviously serious concerns relative to the short-term operation and long-term reliability of that line. Those concerns form the basis for this Level II study.

1.1 CONTRACT AUTHORIZATION

Authorization for the Worland Pipeline Level II Study was granted by contract between the Wyoming Water Development Commission and Forsgren Associates, Inc. dated June 2, 1997. the project sponsor is the City of Worland, Wyoming.

1.2 STUDY ISSUES & OBJECTIVES

The project objective as stated in the Request for Proposal for this project is "to conduct a Level II rehabilitation study to evaluate the deficiencies associated with the asbestos cement transmission pipeline from the city's well field near Bonanza to the city." The study included the following elements:

• Inspection and analysis of the existing system.

• Estimation of remaining life of the transmission line and assessment of the feasibility of continued use of the pipeline.

• Recommendations for improvements to the system as well as operation and maintenance issues targeted at extending the life and reliability of the conveyance system.

• Prepare conceptual designs and preliminary cost estimates for specific proposed improvements to the system.

1.3 PIPELINE FAILURE MECHANISM

In considering the probable cause of failure in Worland's transmission pipeline, it is important to note that the line has functioned very well for approximately 15 years since its construction. There is no evidence of internal or external deterioration of the pipe. The problems appear to be primarily associated with the pipe joints, particularly in high pressure areas. This is likely a localized problem associated with construction (pulled joints, etc,) rather than with the overall integrity of the pipeline. Marginal joints can begin leaking after holding for many years due to dynamic stresses in the pipeline. AC pipe tends to "sand-blast" itself when such leaks occur. This was the case with a small segment of pipe immediately downstream of the Sand Creek crossing. In that case, the leak was discovered and corrected before the pipeline fully failed. However, the stresses associated with draining and filling the line to complete the repair may have contributed to another joint leak opening up in the vicinity of the Sand Creek area break. That leak similarly increased in magnitude and likely saturated the subgrade and bedding soils around the pipe. The weakened bearing strength of the saturated soils, combined with relatively high pressures and pulled joints through this reach ultimately resulted in a catastrophic failure of the pipe.

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The Sand Creek break was, in our opinion, the result of a the soil-structure interaction failure rather than defective pipe materials. The occurrence appears to be localized in its nature and is not indicative of impending catastrophic failure in other locations. We remain somewhat concerned, however, about the over-all integrity of the pipeline joints. Unfortunately, potential joint problems cannot be easily identified until leakage occurs. It would be prudent, therefore, for the city to have appropriate repair materials on-hand to insure that such problems can be corrected in a timely and cost-effective manner.

1.4 RECOMMENDED "IMMEDIATE NEEDS"

This study focused on the condition, capacity, and reliability of Worland's existing water transmission pipeline. The recommendations contained herein, therefore, are intended to address concerns specifically related to those issues. These recommendations primarily involve emergency preparedness, responsiveness, monitoring, and prevention. Specific recommendations are as follows:

1.4.1 Automated Shut-off Valves at Well Head

Worland's artesian wells are located approximately 20 miles from town and are highly inaccessible during various times of the year. The inability to monitor and quickly isolate these wells significantly aggravates the potential damages associated with line breaks, etc. It is recommended that automated pneumatically controlled valves be installed at the wellheads for both wells to address this problem. These valves should be set to close at a controlled rate (to transient surges in the well casings) based on extreme changes in pressures and/or flows typically associated with line breakage. The valves will also provide important shut-off redundancy in the event that the existing valves experience leakage.

1.4.2 SCADA System

It is recommended that the City of Worland install a complete PC-based SCADA system as generally outlined in Table 1. This will allow the system to operate at peak efficiency and capacity. It will also provide a timely warning of system for problems should they occur. In addition, system operators will be able to easily operate key system components in remote locations.

1.4.3 Stored Repair Materials

It is recommended that the city acquire and store basic pipeline repair materials as generally outlined in Table 1.2. Having these materials on-hand will substantially reduce response and repair time in the event that a pipeline failure occurs again in the future. These materials should be suitable stored and protected to insure their long-term usefulness. As repair materials are used, they should be replaced in-kind.

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TABLE 1.1 WORLAND PIPELINE SCADA SYSTEM

STATION SCADA ELEMENTS

solar Power, radio & antenna, RTU, flow meter, pressure transducer, pneumatic valve

HUSKEY WELL #1 control

solar Power, radio & antenna, RTU, flow meter, pressure transducer, pneumatic valve

WELL #3 control

solar Power, radio & antenna, RTU, flow RATTLESNAKE RIDGE meter, pressure transducer

radio/telephone comm., RTU, P.C. & software, pressure transducer @ poly jet,

CHLORINATION/EASTANK tank level, flow meter, actuated valve control

radio/telephone comm., RTU, tank level, flow WEST TANK SITE meter, actuated valve control

MAINTENANCE BUILDING radio/telephone comm., P.C. & software (primary control point)

REPEATER STATION (as/if required)

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TABLE 1.2 WORLAND PIPELINE

MINIMUM SUGGESTED REPAIR MATERIALS ON-HAND

DESCRIPTION QUANTITY

20-inch class 350 DIP with polywrap 500 If

24-inch class 350 DIP with polywrap 500 If

20-inch MJ bend (epoxy coat with ss hardware 2 each

24-inch MJ bend (epoxy coat with ss hardware 2 each

20-inch ss solid sleeve 1 each

24-inch ss solid sleeve 1 each

20-inch AC to 01 adapter (t-60) 2 each

20-inch AC to 01 adapter (t-70) 2 each

20-inch AC to 01 adapter (t-BO) 2 each

24-inch AC to 01 adapter (t-50) 2 each

24-inch AC to 01 adapter (t-60) 2 each

24-inch AC to 01 adapter (t-70) 2 each

24-inch AC to 01 adapter (t-BO) 2 each

24-inch AC to 01 adapter (t-90) 2 each

20-inch X 2-inch saddle 1 each

20-inch X 2-inch saddle 1 each

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1.5 ECONOMIC DATA

1.5.1 Recommended Project Cost Estimate

The estimated cost of the recommended immediate needs outlined herein is $275,000. These costs are summarized in Table 1.3 and are tabulated in detail in Appendix A.

TABLE 1.3 WORLAND PIPELINE

RECOMMENDED IMMEDIATE NEEDS WWDC ELIGIBLE COSTS

Item No. Description Estimated Cost

1. 2. 3.

Emergency Repair Materials Auto Shut-off at Wells SCADAlTelemetry

Preparation of plans and specification Permitting & Mitigation

Construction Cost (from above) Construction Engineering (10%)

Contingency (15%)

Subtotal

Subtotal

Construction Total

PROJECT TOTAL

1.5.2 Probable Project Financing

$ 62,000.00 $ 24,500.00 $113.000.00 $199,500.00

$199,500.00 $ 20,000.00 $219,500.00 $ 30.000.00

$25,000.00 $ 500.00

$249,500.00 $249.500.00

$275,000.00

This project is fully eligible for funding through the Wyoming Water Development program. It is presently VVVVDC's practice to fund projects of this nature with a 50%/50% grant loan mix. The loan would likely be over a period of 20 years with an annualized interest rate of 7.25°A,. This project is also eligible for federal funding through the Rural Utility Service (RUS) program of the USDA. This is a program that favors "Iow-to-moderate income communities". Given the relatively high family income levels in Worland, it is not likely that RUS funding would benefit the City.

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1.6

1.5.3 Projected User Rate Impact

Based on the assumed \f\J\NDC financing package with 2400 connection, the projected average rate impact is approximately $0.46 per connection per month.

WHAT NEXT?

It is recommended that the immediate needs recommendations be implemented and that the project be advanced for Level III 'N\NDC funding accordingly. It is felt that the cost of automated emergency shut-off valves at the wells, a SCADA control system, and acquisition of emergency repair materials represent a modest investment in public health and safety. These items are all viewed as critical in their urgency and implication to the system. Had these improvements and recommendations been implemented at the time of the Sand Creek break, it is felt that the impacts and costs would have been a fraction of what they ultimately were.

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