EAST BAY MUNICIPAL UTILITY DISTRICT
Technical Memorandum No. 5
Delta Tunnel Study Buried Pipeline Alternative
Prepared for: Prepared by: East Bay Municipal Utility District MWH 375 Eleventh Street, MS 504 2121 North California Boulevard Oakland, CA 94623 Walnut Creek, CA 99508
March 17, 2015
MOKELUMNE AQUEDUCT EAST BAY MUNICIPAL DELTA TUNNEL STUDY UTILITY DISTRICT TM-5: BURIED PIPELINE ALTERNATIVE
Table of Contents
EXECUTIVE SUMMARY ...... 1 1.0 INTRODUCTION ...... 2 1.1 Purpose of Study ...... 2 1.2 Mokelumne Aqueducts Delta Tunnel and Pipeline Alternatives ...... 2 1.3 Limitations of Study ...... 3 2.0 PROJECT BACKGROUND ...... 5 2.1 Existing Facilities ...... 5 2.2 Site Geology ...... 5 2.3 Seismic Hazards and Liquefaction ...... 6 3.0 BURIED PIPELINE CONCEPT ...... 9 3.1 Overview of Alignment and Reaches ...... 9 3.2 Vertical Profile ...... 3 3.3 Corrosion Protection ...... 4 3.4 Performance and Risks ...... 4 3.5 System Requirements and Design Criteria ...... 6 3.6 Buried Pipeline Design ...... 7 3.6.1 Pipe Longitudinal Loading and Deflection ...... 7 3.6.2 Pipe Wall Thickness ...... 8 3.6.2.1. Basis of Design ...... 9 3.6.2.2. Internal Pressure ...... 9 3.6.2.3. External Loading / Deflection ...... 9 3.6.2.4. Buckling ...... 10 3.6.2.5. Handling and Constructability ...... 10 3.6.2.6. Summary ...... 10 3.6.3 Pipe Joints ...... 11 3.7 Bent and Pile Design ...... 11 3.8 River and Slough Crossings ...... 13 3.9 Right of Way, Easements and Property Acquisition ...... 14 3.10 Construction Considerations ...... 16 4.0 OPCC ...... 17 4.1 Methodology ...... 17 4.1.1 Pricing Basis of Construction Cost Estimate ...... 17 4.1.2 Estimate Classification ...... 17 4.1.3 Estimating/Scheduling Methodology or System ...... 18 4.1.4 Estimating Accuracy and Contingency ...... 18 4.1.5 Quantities...... 19
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4.1.6 Direct Cost Development ...... 19 4.1.7 Indirect Cost Development ...... 19 4.1.8 Estimate Adders ...... 20 4.1.9 Labor Rate Development ...... 20 4.1.10 Equipment Rate Development ...... 20 4.1.11 Escalation ...... 20 4.1.12 Allowances and Contingency ...... 20 4.1.13 Market Conditions ...... 20 4.2 Assumptions and Limitations ...... 21 4.2.1 Significant Assumptions ...... 21 4.2.2 Construction Methodologies ...... 21 4.2.4 Contingency ...... 23 4.3 Alternatives Cost Comparison ...... 23 5.0 REFERENCES ...... 25
List of Appendices
Appendix A: Opinion of Probable Construction Cost
Appendix B: Classes of Cost Estimates as Defined by AACE
List of Tables
Table 3-1 Reach Summary ...... 10
Table 3-2 Risk Summary ...... 5
Table 3-2: Estimated Land Requirements ...... 16
Table 4-1: OPCC Summaries ...... 23
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List of Figures
Figure Title
1-1 Location Map 1-2 Site Plan 3-1 Buried Pipeline Alternative – Layout of Reaches 3-2 Buried Aqueducts on Piles – Plan View 3-3 Buried Aqueducts on Piles – Section 3-4 Shafts at Water Crossings 3-5 Right of Way and Easement Requirements
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Explanation of Abbreviations
AACE Association for the Advancement of Cost Engineering BDCP Bay Delta Conservation Plan bgs below ground surface cfs cubic feet per second CPT Cone Penetration Test EBMUD East Bay Municipal Utility District EPB Earth Pressure Balance EIR/EIS Environmental Impact Report/Environmental Impact Study ESA Earth Science Associates, Inc. g gram HDPE high-density polyethylene CD consolidated-drained CU consolidated-undrained I.D. inside diameter ksi kilopound per square inch kW kilowatt LiDAR Light Detection and Ranging MGD million gallons per day M magnitude msl mean sea level MWH MWH Americas, Inc. N/A not available n.d. no date O.D. outside diameter O&M operation and maintenance OPCC Opinion of Probable Construction Cost pcf pound per cubic foot PGA peak ground acceleration PSHA Probabilistic Seismic Hazard Analysis psi pound per square inch PVC Polyvinyl chloride
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ROW Right-of-Way SPAD Strategy for Protecting the Aqueducts in the Delta TM Technical Memorandum TBM Tunnel Boring Machine USBR United States Bureau of Reclamation
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EXECUTIVE SUMMARY
A near surface pipeline alternative to replace East Bay Municipal Utilities District (EBMUD’s) existing Mokelumne Aqueduct system in the Delta was prepared for comparison to the proposed deep Delta Tunnel alternative (TM-2). The Delta crossing is a reach 16.6 miles long from Stockton to Bixler in which the existing three aqueducts are at risk to damage or failure due to potential hazards associated with earthquakes, flooding, and settlement. A deep tunnel alternative has been proposed as the preferred alternative for mitigating the identified hazards to the existing aqueduct system. For comparison purposes, buried pipelines on piles with trenchless crossing concept were considered recognizing that the project risk profile would be greater.
The shallow buried alternative consists of twin 87-inch diameter aqueducts buried with a cover of three feet and placed on pile-supported bents at 40-foot intervals. Each bent is supported by eight piles with an average depth of 100 feet. There are four water crossings in which the two aqueducts will be microtunneled independently in a side-by-side arrangement at a depth of approximately 150 feet. For each crossing, a single common shaft is used at each end to drive or receive both microtunnels. For the purposes of this concept, it is assumed that the microtunnels will be constructed using the single-pass method in which the jacked steel pipe is also the final lining or pipe.
To maintain all three existing aqueducts in service during construction of the new buried aqueducts, it will be necessary to offset the new pipelines. The land requirements estimated to complete the work are 68 acres of new permanent right of way, and 126 acres of temporary construction easement. These land requirements could be reduced if one or more of the existing aqueducts could be decommissioned prior to construction.
The OPCC for the buried pipeline alternative is estimated at $960 Million, significantly lower than either of the deep tunnel alternatives. Although the buried pipeline alternative is a relatively robust design for a shallow pipeline that reduces the risk of damage or failure from earthquakes, flooding, and settlement hazards, there remain inherent risks from these hazards that can not be fully mitigated. Therefore, the buried pipeline alternative would be an improvement on the existing aging aqueduct system however, it would not provide the same level of risk reduction to the EBMUD water transmission system a Deep Tunnel through the Delta. Additionally, these cost opinions do not incorporate factors for operational and maintenance costs, repairs, environmental mitigation, or risks associated with the different alternatives.
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1.0 INTRODUCTION
1.1 Purpose of Study The East Bay Municipal Utility District (EBMUD) services the east side of the San Francisco Bay Area, providing water to over 1.3 million people. The aqueducts conveying the water are at risk of failure within the Sacramento-San Joaquin Delta (Delta) due to flooding, seismic hazards, and long term settlement. The EBMUD Delta Tunnel Study developed a conceptual design for a proposed tunnel to replace the existing aqueducts and is presented in TM-2, Delta Tunnel Study Conceptual Design. The purpose of the alternative study presented in this technical memorandum is to develop a conceptual plan and associated order of magnitude cost opinion (OPCC) for a shallow buried aqueduct system for comparison to the deep tunnel. This conceptual plan is for two buried pile supported pipelines with twin microtunnels for each of the river crossings.
The scope of the study is as follows:
Develop the horizontal layout for the pipelines and river crossings with consideration of the existing EBMUD ROW. Develop concepts for the buried pipelines including bents for supports and pile foundations. Develop concepts for the river crossings including shafts and twin microtunnels with approximate sizes. Estimate the land acquisition requirements both for permanent right of way and temporary construction easements. Develop a Class V opinion of probable construction cost (OPCC) for the buried pipeline alternative. Develop this technical memorandum (TM-5) presenting results of the study
1.2 Mokelumne Aqueducts Delta Tunnel and Pipeline Alternatives EBMUD’s 2007 report, Strategy for Protecting the Aqueducts in the Delta (SPAD), recommended a tunnel across the Delta as the preferred long-term mitigation for earthquake and flood hazard risks to the existing aqueducts within the Delta. This report, along with several geotechnical reports and recent Cone Penetrometer Test (CPT) investigations were used as the basis for geologic evaluations presented in TM-1: Preliminary Geologic Characterization.
The deep tunnel design was developed to the conceptual level and is presented in TM-2. The conceptual design is for a 16.5 mile tunnel deep tunnel divided into six segments between seven
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shafts. For most of the reaches, the tunnel invert is positioned at approximate El. -125 feet msl but will likely vary within a band up to 20 feet above or 16 feet below this level. The tunnel is designed to be excavated to 22 foot diameter with a closed face tunnel boring machine (EPB or slurry/mixed) using precast concrete segments for initial support, followed by installation of two 87-inch carrier pipes and the annulus between the tunnel and the carrier pipes would be backfilled with cellular concrete. A variation of the deep tunnel alternative was to design was developed for a 13.75 foot diameter excavated tunnel with a single 111- inch carrier pipe.
The buried pipeline concept presented herein is a potential alternative to the deep tunnel and the concept was developed for cost comparison purposes. The buried concept presented herein is based on geologic conditions presented in TM-1, system and pipeline requirements presented in TM-2, and engineering and construction considerations.
The buried pipeline alternative is approximately 16.6 miles long (Figure 2) using two 87-inch ID steel pipes to convey the water. To accommodate different conditions along the project length, both open-cut and trenchless concepts were developed:
1) Primary – The majority of the length is proposed to be twin steel pipes that are open-cut, buried and supported by pile-supported concrete bents. 2) Waterways – Four river and slough crossings conceptualized to be twin microtunnels staged from deep shafts at each end of the drives. The microtunnel drives would be single pass construction with the jacked casings also serving as the final carrier pipes.
The alignment is divided into 10 reaches consisting of six primary and four waterway crossings. The horizontal alignment for the proposed buried alternative follows the existing Mokelumne Aqueduct ROW as much as practicable to control the cost of new property or easement acquisitions. However, the existing aqueducts are required to remain in service throughout construction, so the new aqueducts need to be offset thereby requiring substantial land acquisition.
1.3 Limitations of Study This report has been prepared by MWH Americas, Inc. The interpretations of data, findings, recommendations, or professional opinions presented are within the limits prescribed by available information at the time of conceptual design development when this report was prepared. In general, for this report, the geologic data are largely based on information obtained by others along the existing Mokelumne Aqueduct, which was made available for this study. Limited new geotechnical data were obtained for this study and included twelve new CPT borings. In addition, the study excluded confirmation of the system hydraulics and the development of hydraulic criteria.
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A listing of the data and reports utilized in the development of this study are included in Section 5.0, References. In the event that there are any changes in the nature, design or location of the project, or if additional subsurface data are obtained or any future additions are planned, the conclusions and recommendations contained in the report will need to be reviewed and updated.
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2.0 PROJECT BACKGROUND
2.1 Existing Facilities The existing Mokelumne Aqueduct System consists of three pipelines as follows: Aqueduct No. 1: The middle of the three pipelines, 65-inch diameter built in 1929, Aqueduct No. 2: The southern pipeline, 67-inch diameter built in 1949 and Aqueduct No. 3: The northern pipeline, 87-inch diameter built in 1963. The segment that is proposed to be replaced extends for approximately 16.6 miles across the Sacramento-San Joaquin Delta area from Stockton near Interstate 5 to Bixler. The delta reach presently consists of approximately 6 miles of buried pipeline, 10 miles of elevated pipelines, and three (3) major river crossings with about 0.5 miles of submerged pipeline. The buried sections are a combination of buried pipeline (without pile support) and buried pipeline pile supported designs. The elevated pipelines are on pile-supported bents with the following configurations: Aqueduct No. 1: Bents at 30 foot spacing and 2 timber piles per bent with the corner piles battered at 1:12. Aqueduct No. 2: Bents at 60 foot spacing and 4 to 6 concrete piles per bent with the corner piles battered at 1:4. Aqueduct No. 3: Bents at 60 foot spacing and 4 to 6 concrete piles per bent with the corner piles battered at 1:3. The bent locations for the three aqueducts are typically aligned. The pile tips range in elevation between El. -20 to El. -70 msl, corresponding to pile lengths of between 20 and 65 feet, with most of the pile tips between elevation El. -40 and El. -60 feet msl.
The three aqueducts are positioned within the EBMUD existing ROW which typically varies from 100 to 160 feet wide, but is occasionally wider especially at rivers, sloughs, and roads. More detailed information on the existing aqueducts is presented in TM-2.
2.2 Site Geology The subsurface conditions at the site are divided into five different geologic strata. The overall description of each of the five strata identified is explained below, from youngest to oldest, are presented in more detail in TM 1: Preliminary Geologic Characterization. The geologic stratigraphy within the depth of interest, approximately the upper several hundred feet below the ground surface is comprised of the following:
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Artificial fill is found along much of the alignment, mainly along the roads and levees, and ranges from thin (less than a foot) to up to about 15-feet-thick. The fill mainly consists of mixed fine sands, silts and clays.
Marsh deposits are derived primarily from the San Joaquin River as floodplain and flood basin deposits and minor natural levee deposits overlying the alluvial deposits. These deposits are interlayered with the organic peat deposits, and can be found above or below the organic layer. The marsh deposits are mainly comprised of silty clays, sandy silts, and clay silts.
Peat and Organic deposits blanket much of the area, within the zone of tidal influence and alluvial deposits above tidal influences. In general, the organic deposits consist of compressible peat with varying amounts of silts and clays.
Holocene Alluvial deposits are typically floodplain/basin and stream channel deposits that are loose to medium dense micaceous sand with low organic content; and soft to medium dense stiff micaceous silt, silty clay, clayey silt, and silt, commonly with carbonate, and locally with oxide nodules. Based on available field data reviewed during this study, these deposits are typically found between El. -20 to El. -70 ft. msl and can be encountered to an elevation of El. -100 ft. msl.
Pleistocene Alluvial deposits are comprised of the Modesto and/or Riverbank Formations, which are generally characterized as dense to very dense silty sand, sand with gravel and very stiff to hard silty clay and clayey silt with gravel that can be slightly cemented and/or indurated.
For the purposes of this study including both the deep tunnel (TM-2) and the buried pipeline alternative presented herein, the upper three strata are combined into one unit. Although these three strata are geologically distinct and have different soil characteristics, they are all relatively soft or loose and have similar geotechnical characteristics. The Holocene and Pleistocene Alluvial deposits are similar in composition, and vary primarily in geologic age, the density of the sands and consistency of the clays. Based on current data, a distinct interface between the two units was not identified. Therefore, these two strata are combined into one unit for the purpose of this study.
2.3 Seismic Hazards and Liquefaction The potential seismic hazards that could impact the proposed project site area have been evaluated in several previous studies based on probabilistic methods using return periods. As part of the present work associated with the conceptual design for the proposed Delta Tunnel and
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buried alternative, MWH reviewed the previous probabilistic methods to determine the likely seismic hazards and peak ground acceleration associated with earthquakes, the results of which are presented in TM 1: Preliminary Geologic Characterization.
The results of probabilistic analysis (EBMUD, 2007) indicate that most delta levees around the islands are expected to fail with a PGA of 0.1 g, which implies a catastrophic levee failure for a 100-year return period earthquake event. For the 500-year return period earthquake, levee failure is almost certain. The vulnerability of levees to fail under the 100-year and 500-year return period earthquakes was taken into account to assess the liquefaction hazards along the aqueducts alignments (EBMUD, 2007). In the vicinity of the aqueducts in the Delta, PGA values for the 100-year return period event range from 0.11 to 0.17 g and for the 500-year return period event, from 0.20 to 0.37 g. Due to the influence of Bay Area faults, the seismic hazard decreases from west to east at these short return periods (McLeod, 2013).
Liquefaction is a process in which strong ground shaking causes loose and saturated sediments to lose strength and to behave as a viscous fluid. This phenomenon can cause excessive ground deformations, failures, and temporary loss of soil bearing capacity, resulting in damage to structures. Ground failures can take the form of lateral spreading, excessive differential and/or total densification or settlement, and slope failure. Generally the liquefaction and associated ground deformation are more prevalent in shallow soils than in deep situations due to higher stresses.
Based on previous studies, the estimated seismic settlement is expected to range between 1 and 6 inches within the island tracts and between 2 and 12 inches in areas closer to (and within) the slough and river crossings (EBMUD, 2007). The seismic settlements between Holt and Stockton are estimated to be approximately 4 to 12 inches, and differential seismic settlements of 5 to 7 inches over short distances (120 feet) are possible.
In general, most soils within the upper two strata (artificial fill and marsh deposits) are liquefiable. The peat and organic soils (Stratum 3) are unlikely to be liquefiable, but could undergo significant strength loss and seismic deformation. The Holocene alluvial soils (Stratum 4) are variable, and include both liquefiable and non-liquefiable layers. Similarly, the Pleistocene alluvial soils (Stratum 5) are variable with a range of liquefaction susceptibilities, and although the sands may be slightly denser than in the Holocene they are still potentially liquefiable. For this study the Holocene and the Pleistocene were not differentiated, and liquefaction evaluations were based on soil characteristics without association to their geologic strata.
Liquefaction potential and settlement for this study were based on data obtained from twelve CPT probes conducted by Gregg Drilling in 2014 along the aqueduct alignment. The post- earthquake settlements were computed by Gregg Drilling and EBMUD using the geotechnical
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software CLiq (GeoLogismiki, 2014) and reviewed by MWH. The CLiq calculations assumed an earthquake magnitude (Mw) of 7.0 and a peak horizontal acceleration at the ground surface (amax) of 0.2g and 0.4g. The results of these analyses indicate that: 1) the soils may be liquefiable to a depth of 100 feet or more, 2) there does not appear to be a readily identifiable liquefiable transition in the soils, and 3) the total liquefaction settlement at the ground surface was calculated to be six inches or more in most areas, and over 12 inches at some locations.
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3.0 BURIED PIPELINE CONCEPT
3.1 Overview of Alignment and Reaches The buried pipeline alternative involves an entirely new conveyance system paralleling the existing aqueducts and consisting of two new 87-inch pipelines. The new aqueducts are to be primarily pile-supported buried twin steel pipelines, except at key waterway crossings where trenchless construction technical will be required, excavation of twin microtunnels are planned in accordance with the following:
Shallow Buried Pipeline: The concept for the transmission system is similar to the existing aqueduct system, but the piles would be driven to a deeper soil layer and the pipelines themselves would be placed below the existing grade with approximately two to three feet of soil cover. The soil cover reduces risks from flooding and scour relative to elevated pipelines. The buried 87 inch steel pipelines are planned to be supported on steel piles with sufficient depth to stabilize the pipelines and reduce risk of damage from soil subsidence, liquefaction settlement and other seismic hazard related risks. Further conceptual design considerations and descriptions are presented below in subsections 3.3 and 3.4. Waterways: At waterway crossings, a shallow profile for the pipelines would likely be subject to strict environmental requirements and would be at risk to flooding and scour. To reduce these adverse factors, the proposed concept is to position the pipelines deep below the waterways using trenchless construction techniques. Twin microtunnels would be constructed at each waterway crossing. There are four waterway crossings planned; at San Joaquin River, Middle River, Old River, and Indian Slough. The crossing of Trapper Slough would be accomplished by the use of buried pile supported pipe similar to other shallow buried sections of the aqueducts.
To address the various requirements along the alignment, ten separate reaches have been developed as shown in Figure 3-1 and summarized in Table 3-1.
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Table 3-1 Reach Summary Approximate Length Existing (Feet) Reach Description ROW Width Comments Shallow Micro- (Feet) Buried tunneled Restricted to existing I I-5 to San Joaquin River 8,975 160 ROW San Joaquin River II 750 NA Crossing Roberts Island. San Likely offset new III 19,300 160, 100 Joaquin River to Holt pipelines to north (1) Likely offset new IV Jones Tract 31,500 100 pipelines to south V Middle River 1,050 NA Likely offset new VI Woodward Island 7,350 100 pipelines to north(1) VII Old River 1,000 NA Likely offset new VIII Orwood East 13,200 100, 120 pipelines to north(1) IX Indian Slough 1,300 NA Need to cross X Orwood West 3,100 230, 100 existing aqueducts(2) TOTALS 83,425 4,100 Notes: (1) The “likely” offsets to south or north are preliminary assessments based on consideration of amount of ROW available, construction access, potential encroachments by existing development, and environmental considerations. Alignment relative to the existing aqueducts to be made in future design phases. (2) Preferred location is on north side of existing aqueducts for most of the reach due to existing ROW, but this will require a crossing of the existing aqueducts to the south side to make the connection at the Bixler Maintenance Yard. The existing aqueducts are buried in this area.
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A key criteria for the pipeline alternative is to maintain operation of the existing aqueduct system until the new pipeline system is on line. Each reach has unique factors relative to the position and layout with factors related to existing ROW, construction access, existing land use, and environmental factors affecting the position of the new aqueducts relative to the existing system. The following summarizes the key factors for each reach:
Reach I: This reach extends from Interstate 5 to the San Joaquin River and consists of buried pipe on piles constructed with open cut methods. The Right of Way is 160 feet wide and the land use is a golf course with residential housing on either side. Due to land use restrictions, acquisition of additional land either for a permanent right of way or a construction easement would likely be impractical. Construction of the new aqueducts within the existing ROW would be difficult due to the existing aqueducts, and a gas pipeline adjacent to and parallel with the existing aqueducts.
Reach II: Microtunnel crossing of the San Joaquin River including shafts at either end. EBMUD has an easement on the east side that appears to be large enough for a shaft, although the existing aqueducts may interfere, thereby requiring additional land, especially for a construction staging area. The shaft at the west side would likely require additional land both for a permanent easement and for a construction staging area. The land use is a golf course and residences to the northeast and agricultural to the southwest.
Reach III: This reach extends from the San Joaquin River to Holt across Roberts Island, and consists of buried pipe on piles constructed with open cut methods. The Right of Way is 160 feet wide at the NE end transitioning to 100 feet at the SW end. The land use is mostly agricultural on both sides, except for a residence on the south near Holt and a road sub-parallel to the alignment located to the south. The new aqueducts could be constructed either to the north or to the south, but it appears that the north is preferable to avoid tight conditions at Holt, and to potentially eliminate the double bend at Holt. Note that an undercrossing of the existing aqueducts would be required for continuation to Reach IV. The alternative position of the new aqueducts to the south may have better construction access and should be considered during design.
Reach IV: This reach extends from Holt across the Jones Tract to the Middle River, and consists of buried pipe on piles constructed with open cut methods. The Right of Way is 100 feet wide with the land to the south agricultural, and to the north is a drainage channel, then a railroad. Although the new aqueducts could
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be constructed to either side, it appears that the south is preferable due complications with the existing drainage and for ease of construction access.
Reach V: This is a microtunnel crossing of the Middle River including shafts at either end. The land is predominantly agricultural, but with some roads and unimproved land. The crossing could be located either north or south of existing aqueducts or even cross diagonally allowing reaches IV and VI to be on opposite sides of the existing aqueducts.
Reach VI: This reach extends from the Middle River, across Woodward Island to the Old River, and consists of buried pipe on piles constructed with open cut methods. The Right of Way is 100 feet wide with the land on both sides agricultural, although the agricultural strip to the north is only 400 to 500 feet wide, then a road, a drainage way and the railroad. The proposed BDCP tunnel crosses the EBMUD aqueducts within this reach. The new aqueducts could be constructed to either side of the existing aqueducts. For the purposes of this study it is assumed that the north position is preferred. However, construction access to the north may be more difficult than to the south.
Reach VII: This is a microtunnel crossing of the Old River including shafts at either end. The land is predominantly agricultural, but with some roads and unimproved land, and docks or a marina on the west bank. The crossing could be located either north or south of existing aqueducts or even cross diagonally allowing reaches VI and VIII to be on opposite sides of the existing aqueducts.
Reach VIII: This reach extends west of the Old River through Orwood East to Indian Slough and consists of buried pipe on piles constructed with open cut methods. The Right of Way is generally 120 feet wide with a strip to the east ranging from 100 to over 200 feet wide at the Old River. The land to the south is agricultural and to the north lies unimproved land potentially with a drainage way and then the railroad. Although the new aqueducts could be constructed to either side, it appears that the north is preferable since the land is unimproved and the drainage way could likely be relocated slightly farther to the north. However, placing the new pipeline to the south would reduce or eliminate the need for land acquisition since the new pipelines may fit within the existing right of way.
Reach IX: This is a crossing of Indian Slough. The existing aqueducts are elevated with footings located within the slough. There is a road with a bridge to the south, and to the north the slough goes through a sharp bend limiting the available land. The Right of Way is 120 feet wide with approximately 60 feet of
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available right of way to the south. This crossing could be either elevated or microtunneled, depending on several factors including design criteria and the acceptable level of risk. For the purposes of this study it is assumed that the crossing is underground constructed via twin microtunnels. Because of the layout of the slough and roads, the microtunnels are laid out to be 1,300 feet long ending on the north side of the existing aqueducts at the west end.
Reach VIII: This reach extends west of the Indian Slough to the Bixler Maintenance Yard, and consists of buried pipe on piles constructed with open cut methods. The Right of Way varies from 100 to 250 feet, generally with extra right of way to the north. The land is a combination of agricultural, residential unimproved, with Orwood Road to the south and the railroad to the north. With available vacant land and right of way to the north at the east end of the reach, and the Bixler maintenance yard to the south at the west end, it is likely that the new alignment will need to cross under the existing aqueducts.
3.2 Vertical Profile The pipeline profile will generally follow the ground surface but with dips for each of the aqueous crossings. As shown on Figure 3-3, the buried pipes are positioned below the existing surface with a nominal cover of approximately two to three feet assumed over the top of the pipe. At each of the crossings, the pipes will be at a depth such that the differential movements from liquefaction are not expected to impair the integrity of the pipes. As previously determined in TM-2 for the large deep tunnel, the depth to which differential movements due to liquefaction will not be of significance has been assumed to be El. -125 feet msl, and the same position is assumed for the microtunnels. The transitions from shallow buried to microtunnels will be at the shafts at each end of the segment.
For operation, inspection, maintenance and repair (O&M) of the pipeline, high points and low points in the profile must be provided and these locations must be accessible and occur only at manholes. Placing a manhole at the high points allows for air valve assemblies to be located at the high points. With low points at manholes, sediment trapped at low points can be relatively easily accessed for removal, and the pipelines can be completely drained for inspection, maintenance, and repair. However, low points must be situated at locations where pipe drainage discharges can be handled appropriately.
Minimum slopes are assumed to be approximately 0.001 ft/ft. With the existing ground being relatively flat, the longer the distance between high points and low points, the greater the potential burial depth at the low points. Greater burial depth leads to higher excavation and dewatering costs, and potentially higher design loads on the pipe and pile system. During final
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design a proper balance needs to be determined between minimum slope, distance between high points and low points, pipe/pile design, and the depth of cover.
3.3 Corrosion Protection Corrosion protection for buried steel water pipes is commonly provided by active cathodic protection systems. At this point, no corrosion investigation has been performed to determine how corrosive the soil is and what corrosion protection measures may be required for the exterior of the pipe. For this project it is assumed that an impressed current system using deep well anodes placed at intervals of approximately one every two miles would be appropriate.
Corrosion protection for the piles and pile bent structural support systems also must be considered, depending upon the selected materials. If concrete pile bents and concrete piles are used, no corrosion protection is required. However, assuming steel piles are used, corrosion protection may be required. This could potentially involve the use of a cathodic protection system and/or coated steel piling. With a buried pile bent system involving piling approximately 100 ft. deep or more, it may be reasonable to assume that there is not sufficient oxygen at depth to support corrosion. In that case, coatings may only be needed for the upper portions of the pile system with no cathodic protection system needed for the piles.
A common design for buried pipe is to use interior cement mortar lining and coating on the pipelines.
Detailed corrosion studies are recommended during preliminary and final design phases to evaluate the corrosive potential of the groundwater, passive measures, in-situ corrosion evaluation systems, and the need for active cathodic protection, as well as for final lining and coating recommendations.
3.4 Performance and Risks The goal of the design for the buried reaches of the aqueducts is to reduce the risks and potential damage to the pipelines from known hazards, especially earthquakes and flooding. Although the concepts presented provide a higher level of reliability than the existing aging aqueduct system through the Delta, the flooding and seismic hazard risks have not been mitigated to the same level as that presented with the deep tunnel alternative.
The shallow buried reaches of the aqueducts are pile supported to reduce differential movement from liquefaction and long-term settlement to a level that is expected to not damage the pipelines. However, there is uncertainty as to the degree of potential liquefaction-induced settlement which remains a residual risk. For each of the river crossings and where the aqueducts cross levees, embankments, and slopes such as river banks, there is an unmitigated risk of
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complete aqueduct failure due to lateral spreading and slope failure during a seismic event. These risks are clearly presented in the DRMS study (URS/JBA, 2011). Although the deep microtunnels at the waterway crossings are expected to be below the active zone for liquefaction, the shafts and buried portions of the pipelines leading to the microtunnels are still vulnerable.
The proposed pipelines would be buried with approximately three feet of cover to provide protection from flooding, especially floating debris that may impact elevated pipelines. The shallow cover is also expected to provide a small measure of protection from localized erosion. However, a levee breach or other major flood event would likely have substantial scour and if located at the aqueducts would likely damage or destroy the pipelines in that area. Some of these risks are addressed or partially addressed in the conceptual design, while others are inherent to a shallow pipeline and would be problematic and impractical to mitigate. The following table summarizes these risks:
Table 3-2 Risk Summary
Risk Accept Mitigate Comments
Extended Submergence X Inaccessible if island flooded Major scour from levee breach X Scour in river bottoms X Microtunnels for crossings Minor scour X Some protection from burial Liquefaction X Piles stabilize pipelines Lateral Spreading X X Piles improve performance, but major lateral spreading would damage the pipelines Slope Failure in EQ event X Landslide of levee causing a breach may impact or destroy shaft(s) at river crossings Floatation X Straps prevent floatation Liquefaction induced settlement X Long term subsidence X Piles to extend below peat Floating Debris X Lateral EQ Loads X
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3.5 System Requirements and Design Criteria The basic aqueduct system criteria developed for this study are the same as those described in Technical Memorandum No. 2 - Delta Tunnel Study Conceptual Design, which is summarized below:
Desired long-term raw water delivery capacity of 325 MGD. Desired interim raw water delivery, with Aqueduct No. 3 in service (pumped state) of 172 MGD. Aqueduct system capable of continuing operation during flood events. Aqueduct system capable of continuing service during and after a seismic event with only minor damage.
Based on information provided by the EBMUD, design of the piping needs to maintain or improve upon the existing system operational parameters described in Technical Memorandum No. 2 - Delta Tunnel Study Conceptual Design, which consisting of the following:
1. Design Pressure: 300 psi
2. Total Combined Flow:
Gravity: 199 MGD Pumped: 326 MGD
3. Flow Separation: Flows from Aqueduct Nos. 1 and 2 combined are required to be separate from Aqueduct 3 flows.
4. Flows:
Aqueduct 1 and 2 combined flow: 94 MGD with gravity flow Aqueduct 3 flow: 105 MGD with gravity flow
5. Interconnections: The existing interconnection facilities need to remain operational with the new facilities to provide for operational flexibility.
The proposed buried pipeline alternative accomplishes the above described operational criteria by combining flows from Aqueducts 1 and 2 into a single 87-inch pipeline and providing a separate 87-inch pipeline to convey Aqueduct No 3 flows.
Loads are induced in a buried pipeline whenever it is subjected to movement relative to the surrounding soil. This may occur when the soil restricts the free movement of a pipeline or when the pipeline attempts to resist the movement of the surrounding soil. The loads on a buried pipeline
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caused by ground displacement are deformation-limited. That is, the soil loads exist only when there is relative displacement between the pipeline and the surrounding soil or supports. Large ground displacements will typically produce pipeline strains well in excess of the elastic levels produced by normal operating conditions, and are a concern if the pressure integrity of the pipeline cannot be maintained. Small ground displacements over long distances will not appreciably affect the stress and strain in a steel pipeline depending upon the backfill material, diameter of pipe, thickness and strength of steel. As a conceptual design level criterion, allowable deformations of the new pipeline on the order of 1-inch to as much as 2-inches over the 40 foot span between new support bents should be acceptable. Such deformations are not expected to have a detrimental effect on the performance of the pipelines.
Additionally, the pipelines may be submerged in flood conditions which may occur either with the pipes full or empty. Therefore, design calculation on the pipe for buckling and deflection need to incorporate a condition with the water at elevation + 10 feet, msl.
3.6 Buried Pipeline Design As shown in Figures 3-2 and 3-3, the buried pipeline reaches are supported on piles to reduce pipe settlement and resulting deformation as compared to the amount of settlement and deformation that would be experienced if the pipelines were laid directly in shallow trenches without pile support. Permanent liquefaction-induced ground deformations of six to 12 inches have been calculated for the majority of the alignment, with a few areas calculated to be over 12 inches. To reduce the differential movements on the aqueducts, the pipes are supported on bents founded on deep piles. Although the piles are founded in soils subject to liquefaction, they are expected to float thereby attenuating settlement as discussed below in subsection 3.5.
The backfill immediately around the pipes is anticipated to be granular pipe zone material for easy placement and compaction, and to provide uniform support. Native soils would then be used above the pipe zone and up to the ground surface. The pipe zone material would be placed at a 1:1 slope up from the bottom of the pipe trench and placed between the pipelines as well as shown on Figure 3-3. The interface between the pipe zone material native fill will need to be designed to prevent the migration of fines.
3.6.1 Pipe Longitudinal Loading and Deflection The pipelines are expected to experience differential movement and resulting deformation along the pipes as a result of settlement from liquefaction and subsidence. The pipelines will need to be designed for both ground loading and deflection. Ground loading is from settlement of the ground around the pipelines while the pipes remain at a stationary elevation thereby forcing the pipes to function as beams between the bents. Design of the pipe needs to include evaluation of
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many factors including: direct loading, induced loading from distortions, internal and external pressures, ring bending, longitudinal buckling, ring buckling, allowable longitudinal deflections, and allowable ring deflections. Additionally there will be stress concentrations at each of the bents, and the cradles, tie downs and pipe will need to be designed accordingly. Due to the complexity of these factors, a numerical model will likely need to assist in design which is beyond the scope of this study.
As an approximation of likely pipe requirements, guidelines for deflection of buried pipes were used. However, these guidelines are for pipes in conventional burial situations without pile supports, which impart stress concentrations and a substantial degree of complication to the system. Using these guidelines (ASCE 2001, Design of Buried Steel Pipe, Appendix A, 2001) and to remain serviceable and not require repairs, the allowable distortion of the pipe was limited to 0.33 percent strain. Based on this limit, the allowable distortion for a 40 foot length of pipe between bents is approximately 4.4 inches. A summary of these evaluations is presented in TM- 2.
Future design of the pipe will need to include an evaluation of the interaction of stresses and forces, with special attention to stress concentrations at the bent supports. Due to the high loads that can be generated by the ground, it is likely that a thicker pipe to resist the loads would not be practical, and instead the design would need to focus on reducing stresses through a combination of reducing ground loads, reducing differential movements, allowing pipe distortions, and reduction of stress concentrations. The pipe thickness presented below is consistent with similar water pipe designs, and it is likely that the pipe would be close to this thickness when all of the factors are considered.
Based on engineering judgment and our experience with similar buried pile supported pipes, the system presented consisting of eight piles, each approximately 100 feet long, is expected to control differential settlements within this limit.
3.6.2 Pipe Wall Thickness A preliminary evaluation of the buried steel pipe has been conducted to determine the approximate pipe wall thickness. Calculations have been performed for a typical buried steel pipe for internal loading, external loading (buckling) and handling. Results show that a pipe wall thickness of approximately 0.641 inches is needed for 42 ksi steel for typical buried steel pipe. For the conditions evaluated, internal pressure would be the governing condition for pipe wall thickness.
However, for buried pipe supported by piling and subjected to additional seismic loading conditions there are additional vertical and lateral soil loading conditions that must be considered as well, and the pipe must be thicker than what would be required for a typical buried pipe.
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Determining the impact of these additional factors involves additional complex structural calculations that are beyond the scope of this conceptual evaluation. Therefore, for this analysis we have assumed that approximately an additional 1/8 inch of wall thickness is needed to handle the additional bending stresses from gravity and seismic demands placed on the pipe wall. This results in an overall wall thickness of approximately 0.76-inches, or just over ¾ of an inch. The final required thickness may vary with different steel strengths, design criteria and loading conditions to be determined during final design. The following summarizes these preliminary evaluations.
3.6.2.1. Basis of Design Steel pipe design for the proposed buried pipeline alternative was preliminarily designed with consideration of the following conditions:
Twin Pipes: 87 inch I.D including ¾ inch CML resulting in a steel I.D of 88.5 inches. Internal water pressure: 300 psi. Groundwater extending to the ground surface Vacuum pressure: 14.7 psi. Steel type: 60 ksi ultimate/42 ksi yield. Allowable stress of 50% of yield strength.
3.6.2.2. Internal Pressure The required thickness of the steel plate has been determined based on the allowable stress described above. Based on this calculation and the above conditions, the required thickness based on internal pressure was determined to be 0.6413 inch for the 87 inch pipe. The steel thickness could potentially be reduced with the use of higher strength steel.
3.6.2.3. External Loading / Deflection External Loading / Deflection was calculated based on AWWA M-11 calculations. For mortar lined and mortar coated steel pipe, AWWA M-11 limits pipe deflection to a maximum of 3% in order to avoid potential damage to the mortar lining and coating. The wall thickness required to handle anticipated external loading/deflection limits is less than the 0.6413-inch steel required to handle internal pressure. Therefore deflection is not the governing criterion. (Note that MWH typically recommends limiting the deflection to 75% of the AWWA allowable deflection or 2.25% for mortar lined steel pipe. Since an additional allowance of 1/8 inch has been added to the wall thickness to address the additional bending
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stresses from gravity and seismic demands placed on the pile supported pipe, deflection will be reduced and the pipe meets this more stringent deflection criterion as well.
3.6.2.4. Buckling Critical buckling pressure was estimated based on AWWA M-11 calculations. Critical buckling pressure is a function of steel thickness, pipe radius, and steel strength. The allowable buckling pressure has been estimated based on the pipe diameter, an assumed E’ value of 500 psi, and for a factor of safety of 3.0. For a pipe wall of 0.6413 (based on the minimum wall to handle internal pressure) the calculated negative pressure under assumed dead load/live load conditions (assume HS20 live load) is less than the allowable buckling pressure. However, the calculated negative pressure under vacuum conditions (-14.7 psi or full vacuum condition is assumed) is approximately equal to the allowable buckling pressure when applying a safety factor of 3.0. Furthermore, since an additional allowance of 1/8 inch has been added to the wall thickness to address the additional bending stresses from gravity and seismic demands placed on the pile supported pipe, the allowable buckling pressure is increased. Therefore, preliminary calculations indicate that the pipe should be safe and should not buckle under these load conditions. However, this will need to be checked carefully during final design based on E’ values determined for the existing soils, the proposed trench backfill conditions and based on actual live loads to be allowed above the pipe.
3.6.2.5. Handling and Constructability Minimum pipe thickness for handling and construction requirements has also been evaluated using the following AWWA criteria for loading and unloading, transportation, and lifting:
t = (D+20)/400 t = D/240 ( mortar lined)
Based on these criteria the required minimum pipe wall thickness was determined to be 0.3625 inch. Therefore handling is not the governing criterion.
3.6.2.6. Summary On the basis of the results of analyses for different standard load cases, corresponding required pipe wall thicknesses have been calculated. In accordance with the results, the required thickness for internal pressure, external loading/deflection, buckling, and handling/constructability requirements indicate that internal water pressure is the governing factor for the pipe wall thickness design. Based on the results for 42 ksi steel, a pipe with a 0.641-inch thickness meets these basic design and construction requirements. However, as
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described previously above, an additional 1/8-inch of wall thickness has been included to account for additional bending stresses from gravity and seismic demands placed on the pipe wall due to the buried, pile supported pipe configuration. This results in an overall wall thickness of approximately 0.76-inches, or just over ¾ of an inch.
3.6.3 Pipe Joints Lap welded joints are assumed. The joints must be welded using fillet welds from the inside and outside of the pipe in order to achieve sufficient strength to address anticipated seismic loads (It is assumed that full butt welded pipe joints will not be required). However, these lap welded joints will be the weakest point in the pipeline in terms of their ability to handle bending stresses. Therefore, it will be important to locate the lap welded joints at or near the inflection points in the bending stress diagram, where bending stress is minimal.
3.7 Bent and Pile Design The design optimization of a pile supported pipeline, whether buried or elevated, involves consideration of a number of key variables including: piling material options (e.g. steel H piles, Steel pipe piles, precast concrete, etc.), pile bent materials (steel, precast concrete, cast-in-place concrete, etc.), pile spacing, pile length, splicing requirements, equipment access, transportation of materials, etc. This is an analysis that is beyond the scope of this conceptual evaluation. For the purposes of this evaluation we have developed what we believe represents a reasonably cost effective conceptual design based on experience with similar pile supported, buried pipelines.
Figures 3-2 and 3-3 illustrate the proposed conceptual design features for the buried pipeline alternative. The new steel pipelines are planned to be supported on reinforced concrete pile caps spaced at 40 feet on center. This bent spacing is appropriate to accommodate the loading not only for the two 87-inch pipes full of water, but also vertical and lateral ground loads during both static and dynamic seismic loading. The bents are planned to be six feet thick and made of reinforced concrete to encase the tops of the pipe piles in a fixed head condition to allow greater development of the bending moment capacity of the pipe piles for use in resisting the seismic demands.
The cast in place concrete pile caps are supported on eight driven 24-inch diameter ½ inch wall steel pipe piles. The piles are planned to be vertical rather than battered as was used for the existing Aqueducts. Vertical piles are expected to have better performance due to the following factors:
1. Reduced downdrag effects on the piles. Downdrag increases vertical loads, and increases the length and depth required for the piles.
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2. Reduced bending from downdrag. Vertical settlement around battered piles can result in bending and failure of the piles. 3. Larger lateral loads. Downdrag on battered piles occurring during liquefaction can impart significant lateral loads into battered piles, pile caps and pipelines resulting more potential failure points and requiring stronger pipelines, pile caps and piles.
Without the use of the battered piles, lateral loads on the pipeline/piles system are resisted by both passive soil pressure on both the concrete pile caps and pipelines, and bending of the piles. The pile heads are fixed into the pile caps with headed studs allowing them to have greater rigidity than pinned head piles to control lateral deformation.
The 24-inch diameter pipe pile lengths are expected to range from 60 feet to 120 feet in depth as needed (depending upon soil conditions along the length of the alignment) with an average length for cost estimating of 100 feet. Evaluation of liquefaction and the resulting settlement based on 12 CPT soundings conducted in 2014 showed that there is liquefaction potential to a depth of at least 150 feet. Furthermore, there does not appear to be a sudden change in strata or subsurface conditions below which liquefaction is substantially reduced. Based on these conditions the use of end bearing piles driven to firm strata is impractical, so use of piles to firmly anchor the bents and prevent settlement or differential settlement is not realistic. However, the piles in the lengths proposed are expected to provide a stabilizing force during seismic events by spanning across liquefiable and non-liquefiable zones thereby providing partial support of the pipelines and significantly attenuating settlements.
For the pile driving operation many safeguards will need to be put in place to make sure the existing aqueducts remain operational, adjacent farming operations can continue and the new construction is not damaged including:
1. Detailed pre-survey of all the existing improvements such as existing aqueducts and structures so that during construction, appropriate monitoring can be implemented to make sure existing aqueduct damage/disruption does not take place. 2. The fragile mortar lining of the existing aqueducts can be damaged, potentially affecting flow and longevity of the existing pipelines due to the energy from pile driving. 3. Limits on the energy imparted by the pile driver need to be enforced and monitored through the specifications. This may involve the use of Pile Driving Analyzers (PDA’s) and decibel meters at a minimum. 4. Still photo and videography surveys of existing adjacent improvements are also necessary to document the “before” conditions to establish baselines of the pre-construction condition of adjacent facilities and improvements. 5. At any moment the results of the ongoing monitoring and surveys may warrant implementation of alternative pile driving and construction means and methods.
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3.8 River and Slough Crossings The aqueducts are required to cross three rivers (San Joaquin, Middle and Old) and Indian Slough. At the three rivers, the current aqueducts for these crossings are buried beneath the river channels and covered with rock. At some locations, the pipeline is supported with piles. For example, at Indian Slough the existing aqueducts are raised above the water level and supported on piles. Installation of a shallow buried concept for the aqueous crossings would subject the pipelines to a rather high level of risk from flooding and scour, and would require pile supports to mitigate liquefaction induced deformations. Additionally, construction of a shallow buried design through the rivers is expected to require substantial environmental studies, permitting, and remedial measures. Therefore, a shallow buried concept for the waterway crossings was determined to be undesirable, and a deep profile concept was developed using microtunneling methods.
The waterway crossings range in length from approximately 750 to 1,300 feet long, which lengths are suitable for use of the microtunneling method. The microtunneling method is a single-pass approach in which a steel pipe is jacked into the ground providing support during tunneling, and also serving as the carrier pipe. The microtunneling operation uses a remote controlled closed face tunnel boring machine which is commonly a slurry machine but can be an earth pressure balance machine. Human entry into the tunnel is not common and used only for maintenance and repairs. Cuttings are removed with either a slurry pipeline (slurry machine) or an auger (EPB machine). Two independent drives, one for each pipeline, was chosen to efficiently utilize the TBMs and for an overall lower costs. Although a single large diameter tunnel — such as 21 feet O.D. for the base concept of a single deep tunnel — could be used, this would result in a high capital cost for the TBM, for mobilization and setup, and for segment manufacture.
For the purposes of development at this stage, the depth of the microtunnels was assumed to be the same as for the base design of a single deep tunnel with an invert El. of -125 feet msl. At this location, previous evaluations determined that differential movements from liquefaction would not impair the integrity of the pipelines. Note that the tunnel invert will likely vary within a band up to 20 feet above or 16 feet below and below this level as determined in subsequent design phases.
A shaft will be required at each end of each water crossing to launch are retrieve the TBM for each drive. A single shaft is more efficient that two side-by-side shafts because of the tunnels are relatively close and the required work area for the jacking frame of approximately 30 feet or more. See Figure 3-4 for the plan and section of the shafts. For the purposes of development at this stage, the shafts were assumed to be constructed the same as for the base deep tunnel concept using structural slurry walls for ground support and a base slab placed with tremie
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methods. See TM-2 for details. Following completion of the microtunnels, vertical riser pipes will be installed in each shaft and encased in concrete, also consistent with the design for the deep tunnel and presented in TM-2.
3.9 Right of Way, Easements and Property Acquisition EBMUD owns the Right of Way (ROW) within which the existing three aqueducts are situated. A primary consideration is to position the proposed buried pipeline alternative facilities within the existing ROW to the extent that this is practical. Use of the existing ROW reduces acquisition of land and easements, and associated complications with construction and aqueduct operation.
The existing ROW varies in width from 66 to 160 feet. The three aqueducts are generally centrally located within the ROW with Aqueduct 3 situated to the north, Aqueduct 2 to the south, and Aqueduct 1 in the center. The spacing between the aqueducts is typically between 15 and 25 feet, but is often greater especially at river crossings. The buffer between the aqueducts and the ROW limits varies from 15 to 50 feet based on aqueduct centerlines. The existing ROW and alignment of the three existing aqueducts are presented in TM-2 (Figure 4-1, in 19 sheets).
A key consideration with the new aqueducts was to utilize the existing aqueduct ROW and existing EBMUD land to the extent possible. However, the existing aqueducts must remain operable until the new system is complete, requiring the new aqueducts to be offset. The key factor is the practical distance for construction between the outermost existing aqueduct and the new aqueducts.
For efficient construction, the new aqueducts will need to be offset from the existing aqueduct by approximately 32 feet from center-to-center of the closest pipes as shown in Figure 3-5. This distance allows for a 17 foot deep excavation with 1H:1V side slopes and a three foot buffer to the outside the bents for the existing nearest aqueduct. The use of a 1:1 slope will require dewatering. This distance could be reduced with the use of shoring.
The use of shoring was considered and rejected due to practical considerations and the likely high costs. Shoring against one side of the excavation would require either a cantilever sheet pile system or tiebacks. Additionally, the piles for the existing aqueducts will interfere in some areas with a shoring system using a deep foundation such as for a cantilever approach. Additional concerns are for vibrations associated with driving sheeting, and effects of ground deformations on the existing aqueducts. In summary, the use of sheeting on one side of the excavation next to the existing aqueducts could be accomplished to reduce land acquisition requirements, but would be costly and would practical and technical challenges.
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Although piles for the existing aqueducts are battered, the layout presented is not expected to result in interference with the existing piles. At the location shown, the outside edge of the nearest new pile is approximately 28 feet from the nearest existing aqueduct centerline. For comparison: On the south side, the piles for Aqueduct 2 are battered at 1H:4V resulting in a lookout of 18 feet from pipe centerline (assumes 60’ piles and 3’ offset from C.L.) and on the north side, the piles for Aqueduct 3 are battered at 1:3 resulting in a lookout of 24 feet (60’ piles and 4’ offset from C.L.).
With the position of the new aqueducts as shown, the crucial distances for land use are:
New Permanent Right of Way: 68 feet from the center of the outermost existing aqueduct. This distance is the outside limit of the excavation which will allow future excavation (although not construction support activities) to be conducted within the new Right of Way. Temporary Construction Easement: 65 feet from the new Right of Way. This distance makes allowances for a single-lane construction access road, laydown area for a single pipe, and a two running stockpiles for topsoil and trench excavation totaling 40 feet wide.
In addition to land requirements for the new aqueducts each construction contract requires a general staging area and site access roads, and adequate space for office trailers/parking, worker facilities, materials laydown, and miscellaneous work areas which was assumed to be approximately three acres. Also, each shaft at each river crossing needs an area for one or two cranes, temporary muck storage, and construction traffic flow, which was assumed to be 3.5 acres. The estimated land acquisition needs are summarized in Table 3-2.
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Table 3-2: Estimated Land Requirements New Permanent Temporary Construction Easement Length ROW Reach Description (ft) Width Area Width Area Staging Total (ft) (Acres) (ft) (Acres) (Acres) (Acres) I I-5 to San Joaquin 8,975 NA* 0 3 3 River II San Joaquin River 750 .25 7 7 III Roberts Island 19,300 44 20 50 30 3 25 IV Jones Tract 31,500 38 28 50 47 3 39 V Middle River 1,050 1 7 7 VI Woodward Island 7,350 38 6 50 11 3 11 VII Old River 1,000 -- .5 7 7 VIII Orwood East 13,200 38 12 50 20 3 18 IX Indian Slough 1,300 .5 7 7 X Orwood West 3,100 .25 2 1 Totals 68 110 43 126 Note: * No land for additional Right of Way is available due to residential neighborhood developed to limits of existing ROW.
3.10 Construction Considerations This alternative must be constructed parallel to the existing aqueduct system so that the existing facilities can remain in service throughout the main construction work. Once the new facilities are constructed, in place, tested and disinfected the final tie-in connections can be made at either end of the system.
At certain locations the length of some of the pipe piles may warrant delivery in multiple sections requiring a field completed full penetration butt weld after driving the initial pile length.
Construction Access, Temporary roads, protection of agricultural soils from compaction and damage in the temporary easement area (including possible topsoil stripping and replacement) will also be needed to keep the agricultural interests whole.
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4.0 OPCC This section describes the construction approach, assumptions, and anticipated ground conditions used as a basis to provide an Opinion of Probable Construction Cost (OPCC) and preliminary construction schedule for the proposed Delta Tunnel, for the three alternatives. The Opinions of Probable Construction Cost prepared by MWH are classified according the Association for the Advancement of Cost Engineering International (AACE).
4.1 Methodology
4.1.1 Pricing Basis of Construction Cost Estimate The Opinion of Probable Construction Cost (OPCC) reflects the estimator’s opinion as to the probable costs that a “prudent” contractor would include in his tender to construct the defined facilities. The OPCC does not capture framework costs borne by the owner for pre-construction activities or for expenses related to the management and support of field construction activities. The OPCC is intended to be an indication of fair market value and is not necessarily a predictor of lowest bid. Fair market value is assumed to be a mid-range tender considering four or more competitive bids. Finally, OPCC pricing is predicated on the contractor’s compliance with all contract specifications and design parameters during field execution activities.
4.1.2 Estimate Classification As noted above, estimates are usually classified in accordance with the criteria established by the Association for the AACE’s Cost Estimate Classification System referred to as Standard Practice 18R-97. The AACE Cost Estimate Classification System maps the various stages of project cost estimating together with a generic maturity and quality matrix, which can be applied across a wide variety of industries and capital infrastructures.
This estimate is considered consistent with Class 5 classification criteria described by AACE as:
Class 5 Estimate is prepared based on limited information, where the preliminary engineering is from 1 to 5 percent complete. Detailed strategic planning, business development, project screening, alternative scheme analysis, confirmation of economic and or technical feasibility, and preliminary budget approval are needed to proceed. Examples of estimating methods used would be equipment and or system process factors, scale-up factors, and parametric and modeling techniques. The expected accuracy ranges for this class estimate are –15 to –30 percent on the low side and +20 to +50 percent on the high side.
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Although there are many factors depending on the type and complexity of the project, generally MWH interprets the classes defined by AACE as the following scopes/work efforts:
Class 5: Conceptual Design - between 0 and 2 % design; Class 4: Preliminary Design Phase - between 1 and 15% design complete; Class 3: Design Development Phase – between 10% and 40% design complete; Class 2: Construction Document Phase – between 30 to 75% design complete. Class 1: Check Estimate – between 65 to 100% design complete
4.1.3 Estimating/Scheduling Methodology or System To support productivity and pricing assumptions, multiple software tools are available. For estimating process for water conveyance facilities, the Timberline (TL) cost estimating software coupled with the Richardson Cost Database were used. Estimates of heavy-civil infrastructure are completed in International Project Estimator (IPE) software coupled with a proprietary in- house crew database. Both estimating systems are well known industry tools and are updated yearly. Other commercial pricing databases including RS Means, Mechanical Contractors Association (MCA) and National Electrical Contractors Association (NECA) are also available.
Detailed construction schedules are completed in Primavera P6 project management software.
The following table summarizes the typical estimating methodology employed relative to AACE cost estimate classification:
AACE System Methodology 5 Excel Parametric/Stochastic 4 Excel Semi-detailed Unit Price 3 IPE/TL Detailed Crew Analysis 2 IPE/TL Detailed Crew Analysis w/ Budget Quotes 1* IPE/TL Detailed Crew Analysis w/ Firm Quotes * Class 1 cost estimates are reserved for actual contractor proposals that factor in final subcontractor quotes and firm vendor materials pricing.
4.1.4 Estimating Accuracy and Contingency AACE provides guidance with respect to estimating accuracy and typical contingencies. Estimating accuracy has been addressed by the probabilistic analysis of the price variability as described in the table below. This table provides some basic guidance from AACE regarding contingency level recommendation relative to estimate class and input design.
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AACE Class Design Accuracy Range Typical Contingency 5 <5% ‐35% to +50% 20% to 40% 4 <15% ‐25% to +35% 10% to 30% 3 10%‐40% ‐15% to +20% 5% to 20% 2 50%‐99% ‐10% to +20% 0% to 10% 1* 100% +/‐5% 0% to 5% *Class 1 estimates are reserved for actual contractor proposals that rely on finalized bidding documents and access to all pre-tender addendums.
Based on the level of detail of the design presented in this memorandum, and based on the limited geotechnical investigations, etc. contingency allowances were applied to minimize the risk of cost deviation in relation to future quantity refinement. It would be appropriate to allow a contingency in excess of 20%.
4.1.5 Quantities Preliminary conceptual design sketches and/or other available project engineering conceptual design criteria and information were used to determine the OPCC quantity basis. The furnished quantity inputs were not validated by the estimating team and remain a source estimate deviation until future design refinement allows for rigorous verification of the quantity basis.
4.1.6 Direct Cost Development Directs costs representing the Project’s fixed physical scope have been estimated against a work breakdown structure (WBS) to organize the estimate details. Direct cost detail is decomposed to multiple sub-levels, which are referred to as item activities. Class 5 and 4 estimates typically apply all-in unit prices against the line item quantities whereas Class 3 and 2 estimates derive pricing under a crew based productivity analysis per line item.
4.1.7 Indirect Cost Development Indirect costs representing the contractor’s time related variable field management expenses or general conditions (GCs) costs are factored to Class 5 and 4 OPCCs in a top-down approach as a function of running direct costs. For Class 3 and 2 OPCCs, indirect costs are estimated in a bottoms-up fashion to determine actual resource needs in relation to the proposed construction duration schedule.
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4.1.8 Estimate Adders Similarly, in accordance with normal practice for Class 5 estimates, add-ons representing the contractor’s allowances for home office overhead expenses, sales taxes, insurance costs, risk provision and fee are added to the cost estimate as a function of running direct costs.
4.1.9 Labor Rate Development As a Class 5 cost estimate, this estimate relies on all-in historical database prices and does not involve development of hourly rates for labor and equipment resources. A more detailed approach using all-inclusive labor rates built-up from local wage determinations would be used for future preliminary design and final design phases (i.e. Class 3 and 2) estimate updates.
4.1.10 Equipment Rate Development In a similar manner to the labor rate development, this Class 5 cost estimate has generally relied on all-in historical database prices and has not typically required development of hourly rates for equipment resources,
4.1.11 Escalation Estimated capital costs reflect current (Q3-2014) price levels consistent with the OPCC publish date and does not include adjustments for forward cost escalation as the schedule for implementation of the project is currently unknown.
4.1.12 Allowances and Contingency Allowances have been made in the estimate where there is not a developed conceptual design for a specific feature, but it is required for construction. These items have been identified as allowances in the estimate. The only specific allowance included in the estimate is an allowance for unlisted items which has been included to cover items that are known to be included in the works but have not been detailed or measured at this early stage of design.
The OPCC excludes an allowance for the owner’s management reserve, which represents the owner’s contingency for changed field conditions.
4.1.13 Market Conditions Unprecedented market volatility has been a significant factor in contractor pricing over the last several years. Current market conditions have shown an aggressive approach to pricing with contractors assuming more risk to win project work. Consequently, while the market price may be significantly under the reported “fair valuation” of the OPCC, owners need to be aware of the increased potential for claims and other compensation demands that contractors may employ to
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offset aggressive bidding strategies. This could affect the final price of the work being performed.
4.2 Assumptions and Limitations
4.2.1 Significant Assumptions The OPCC was prepared in 2014 dollars. Construction of the new aqueducts and microtunnels is anticipated to begin for some time (2020 or later). No cost escalations are included. These costs do not include related cost to the Owner such as land acquisition, financing, engineering, and environmental compliance.
The evaluations performed for this study were based on the following assumptions. Limitations identified during evaluation of the tunnel and alternatives also listed below.
Existing geologic information was used to develop the conceptual geologic profile. Project layout for the various alternatives presented herein is conceptual in nature and are based on experience on similar projects. Design development was not performed. Costs are based solely on similar projects with adjustment factors. Competitive bid conditions will prevail at tender. Contracting strategy assumes design-bid-build project delivery method and includes multiple contract packages. Contracts shall be let every six months in order to maximize competition. No vendor quotes were obtained by MWH. A concept was developed to the extent necessary to provide an initial comparison of potential costs. Conceptual level details were prepared to the extent necessary to size major project features and to identify construction considerations. Environmental impacts for were not considered.
4.2.2 Construction Methodologies Method of Pipe Installation: Open cut with dewatering and without shoring. Piles: Driven steel pipe piles Microtunneling: Slurry or EPB microtunnel with jacked steel pipe. Anticipated Construction Method of Shafts:
» Slurry walls for support (other methods are available). » Internal excavation with clam bucket in the wet.
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» Base slab placed with tremie methods. » Permanent manhole and chamber.
Normal Working Hours: Five (5) days/week with two 10-hour shifts/day for tunnel and underground production work, one (1) 10-hour shift per day for surface work and shafts/portals excavation. Competitive Bidding Process: A bid for all work completed under the four (4) construction packages and accepted bid prices not to include unplanned allowances. Construction Support Facilities: All construction support facilities and utilities provided by and/or upgraded by Contractor. Costs for Risk: The costs for risk have been assumed to be carried in the Contractors Home Office Overhead and Fee/Profit percentages.
4.2.3 Additional Assumptions / Exclusions The OPCC incorporates the following assumptions or qualifications: Pricing basis is on the 3rd quarter of 2014. Suitable waste areas for excavated material disposal are located within 20 miles of the project site. Land necessary for construction easement can be temporarily acquired by the Owner. Land costs are not included in the OPCC but have been estimated separately as presented below. Sufficient and qualified craft labor resources are available without significant wage premiums. Sufficient and viable construction equipment resources are available without major premium. Industry standard commercial terms will be applied to all procurements. Owner has sufficient and qualified personnel to manage the project to stated cost and time objectives. Sufficient supply of qualified contractors will tender competitive bid proposals. The contracting strategy maximizes competition and promotes project objectives. No external or internal delays to achieving the project approval. Stable resource market conditions and minimal geo-political disruptions.
As developed, the OPCC excludes the following program costs:
Property purchase or land rights expenses. Removal of the existing aqueducts. Owner’s project management and administrative costs; construction management costs; and design and engineering support during construction expenses.
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Owner’s management reserve for changed field conditions Property or consumption taxes Water rights and use fees Facility capital costs. Interest during Construction (IDC). Unconventional environmental mitigation measures. Exposure to hyper-inflationary or hyper-deflationary market conditions. Levee improvement and river bank erosion mitigation costs. Costs associated with improvements to local infrastructure. Mitigation of flooding impacts. Mitigation of wildlife habitat loss. Excessive stream flow releases. Owner insurance coverage policies. Overly prescriptive permit conditions or specifications. Uncommon natural events such as earthquakes and severe weather impacts. Exposure to swelling soils or rebound consequences.
4.2.4 Contingency Contingency is added to the cost estimate to account for unknown risks or unforeseen market conditions. Given the level of accuracy for this estimate (Class 5) a contingency of 20% on all project components and costs including overhead, bonding, and insurance was added into the estimate. The OPCC excludes an allowance for the owner’s management reserve, which represents the owner’s contingency for changed field conditions or other unknown situations or issues.
4.3 Alternatives Cost Comparison Cost opinions for the buried pipeline alternative with comparisons to the two deep tunnel concepts are presented in the following table.
Table 4-1: OPCC Summaries Estimate Alternatives ($ Million) Buried Pipe Alternative: Shallow buried twin 87’ pipes 960 with deep microtunnel water crossings Base: Deep tunnel, 21’ O.D with two 87” carrier pipes 1,650 Alternative Tunnel: Deep tunnel, 13.75’ O.D with a 1,230 single 111” carrier pipe
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An estimate was made of the land acquisition and use requirements for the project as presented above in Section 3.7. Based on an estimated cost of $10,000 per acre to purchase land as provided by EBMUD, land acquisition costs are estimated as follows:
Permanent ROW purchase: 68 acres at $10,000/acre for $680,000 Temporary Construction Easement: 126 acres at $10,000/acre for $1,260,000
Total land cost is estimated to be $1.9 Million.
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5.0 REFERENCES Association of Bay Area Governments, 2011. Liquefaction Maps and Information. Earthquake and Hazards Program. Available:
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Earth Science Associates, Inc., 1992. “Geotechnical Investigation, Earthquake Safety Assessment of the Mokelumne Aqueduct, San Joaquin Delta Crossing, Volume III,” Geotechnical Review Data, June. Earth Science Associates, Inc., 1992. “Draft Geotechnical Investigation, Earthquake Safety Assessment of the Mokelumne Aqueduct, San Joaquin Delta Crossing, Volume 4,” Geotechnical Data Review, July. East Bay Municipal Water District (EBMUD), 1992. Aqueduct #3 Repair Action Plan, Draft. February. East Bay Municipal Utility District, 2008. “River Crossing Alternative Repair Study, (Insert in Section 9.0 of Aqueduct Emergency Response and Recovery Plan),” March. EBMUD, 2007. Strategy for Protecting the Aqueducts in the Delta, Technical Memorandum No.1 – Alternative Identification (Draft), July 3. EBMUD, 2007. Strategy for Protecting the Aqueducts in the Delta, Technical Memorandum No.2 – Preliminary Cost Estimates (Draft), July 25. EBMUD, 2007. Strategy for Protecting the Aqueducts in the Delta, Technical Memorandum No.3 – Risk Evaluation (Draft), August 31. EBMUD, 1999. Topographic Base Maps, Microstation format. GEI Consultants, Inc. Geotechnical Data Reports – Third Mokelumne Aqueduct Seismic Upgrade River Crossings. Fugro Consultants, 2011. Reprocessing and Interpretation of Seismic Reflection Data, Clifton Court Forebay. Letter to Mark Pagenkopp, California Department of Water Resources. July 22. Walnut Creek, CA. GEI Consultants/Roger Foott Associates Division, 1995. “Mokelumne Aqueduct Seismic Upgrade Project,” Preliminary Design, August 3. GeoLogi, 2014. CLiq User’s Manual. Downloaded from: http://www.geologismiki.gr/Documents/CLiq/HTML/index.html. Krug, E.H., Cherven, V.B., Hatten, C.W., and Roth, J.C., 1992, Subsurface structure in the Montezuma Hills, southwestern Sacramento basin, in Cherven, V.B., and Edmondson, W.F. (eds.), Structural Geology of the Sacramento Basin: Volume MP-41, Annual Meeting, Pacific Section, Society of Economic Paleontologists and Mineralogists, p. 41- 60. McLeod, M., 2013. Large Diameter Aqueducts: Use of Interconnections for Improved Seismic Reliability and Transmission, Proceedings of the 8th US-Taiwan-Japan Water System Seismic Practice. Water Research Foundation (WRF), Japan Water Works Association (JWWA), and Water Works Association of The Republic of China – Taiwan (CTWWA). Mokelumne Aqueduct #2, Pile Driving Records, Volume 1, 1948, approximately 500 piles in 600 pages.
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Olivia Chen Consultants, Inc., 1997. “Geotechnical Investigation Data Report, Third Mokelumne Aqueduct Seismic Upgrade,” River Crossing (Spec. No. 1732), East Bank of San Joaquin River, January. Petersen, M. D., A. D. Frankel, S. C. Harmsen, C. S. Mueller, K. M. Haller, R. L. Wheeler, R. L. Wesson, Y. Zeng, O. S. Boyd, D. M. Perkins, N. Luco, E. H. Field, C. J. Wills, and K. S. Rukstales, 2008. Documentation for the 2008 Update of the United States National Seismic Hazard Maps. U.S. Geological Survey Open-File Report 2008-1128. Porter, Urquhart, McCreary and O’Brien, 1950. “Foundation Engineering Report, Third Mokelumne Aqueduct, River Crossing at Old, Middle and San Joaquin Rivers,” March. Robertson, P. K., 2009. Performance based earthquake design using the CPT. Proceedings of the International Conference on Performance-Based Design in Earthquake Geotechnical Engineering (IS-Tokyo 2009), Editors: Kokusho, Tsukamoto & Yoshimine, June 15-18, 2009, Tsukuba, Japan. Robertson, P. K., and K. L. Cabal (Robertson), 2012. Guide to Cone Penetration Testing for Geotechnical Engineering, 5th Edition, November, Gregg Drilling & Testing, Inc., 131 p. Roger Foott Associates, 2009. Mokelumne Aqueduct Seismic Upgrade Project. February 1995. URS Corporation/Jack R. Benjamin & Associates, Inc. (URS/JBA). Delta Risk Management Study (DRMS) – Phase 1, Department of Water Resources (DWR), March. Sharp, M.K., n.d. Liquefaction at Depth Initiative, 13 p. Steedman, R.S., and M.J. Sharp, 2001. Liquefaction of Deep Saturated Sands under High Effective Confining Stress. Proceedings of the 4th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics (CD-ROM), University of Missouri-Rolla. Third Mokelumne Aqueduct, Structural Locations, Elevations and Pile Data for Elevated Pipe, 12 pages, about 900 piles, November 1967. Third Mokelumne Aqueduct, Concrete Pile Details, 3 pages, December 1967. Torres, R. A., N. A. Abrahamson, F. N. Brovold, G. Cosino, M. W. Driller, L. F. Harder, N. D. Marachi, C. N. 7 Neudeck, L. M. O’Leary, M. Ramsbotham, and R. B. Seed, 2000. Seismic Vulnerability of the 8 Sacramento-San Joaquin Delta Levees. CALFED Bay- Delta Program, Levees and Channels Technical 9 Team, Seismic Vulnerability Sub- Team. April. Treadwell and Rollo, 2010. “Geotechnical Investigation, Mokelumne Aqueduct No. 1, Anchors 2480 and 2580, Stockton and Brentwood, California,” December. URS/JBA, 2007. Delta Risk Management Study (DRMS) Phase 1 – Technical Memorandum, Seismology, Department of Water Resources (DWR), June 15. URS/JBA, 2011. Delta Risk Management Study (DRMS) – Phase 2, Department of Water Resources (DWR), June. Weber-Band, J., 1998, Neotectonics of the Sacramento-San Joaquin Delta area, east-central. Coast Ranges, California: unpublished Ph.D., University of California, Berkeley, 216 p.
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WGCEP, 2003. Earthquake Probabilities in the San Francisco Bay Region b: 2002-2031. U.S. Geological Survey Open-File Report 03-214. WGNCEP, 1996. Database of Potential Sources for Earthquakes Larger than Magnitude 6 in Northern California. USGS Open-File Report 96-705. Wiss, Janney, Elstner Associates, Inc., 2010. Geotechnical Investigation – Mokelumne Aqueduct No. 1 Anchors 2480 and 2580. December. Wong, I. and M. Dober, 2007. Screening/Scoping Level Probabilistic Seismic Hazard Analysis for Buckhorn Dam, California. Unpublished Report. Prepared for Bureau of Reclamation. Prepared by URS Corporation. Youd, T. L. and S. N. Hoose, 1978. Historic Ground Failures in Northern California Triggered by Earthquakes. U.S. Geological Survey Professional Paper 993. U.S. Government Printing Office, Washington, DC. Youd, T. L., I. M. Idriss, R. D. Andrus, I. Arango, G. Castro, J. T. Christian, R. Dobry, W. D. Liam Finn, L. F. Harder Jr., M. E. Hynes, K. Ishihara, J. P. Koester, S. S. C. Liao, W. F. Marcuson III, G. R. Martin, J. K. Mitchell, Y. Moriwaki, M. S. Power, P. K. Robertson, R. B. Seed, and K. H. Stokoe II, 2001. Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils. ASCE Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 10, October, p. 817-883. Zhang, G., 2001. Estimation of Liquefaction-Induced Ground Deformations by CPT&SPT-Based Approaches. Ph.D. Thesis in Geotechnical Engineering (Advisor: P. K. Robertson), Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada, 314 p. Zhang, G., P. K. Robertson, and R. W. I. Brachman, 2002. Estimating Liquefaction-Induced Ground Settlements from CPT for Level Ground. Canadian Geotechnical Journal, Vol. 39, p. 1168-1180. Zhang, G., P.K Robertson, R. W. I. Brachman, 2004. Estimating Liquefaction Induced Lateral Displacements Using the SPT and CPT, ASCE, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 130, No. 8, 861-871.
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FIGURES
3/17/15 Document Path: \\Usboi1s02\gis\_Projects\EBMUD_Mokelumne\_MXDs\TM5\MWH_Location_Map_TM5_8x11_Landscape_12262014.mxd LEGEND
Mokelumne Aqueducts Tunnel Mokelumne Aqueducts Alignment
Sacramento
Santa Rosa
Pardee Reservoir
Fairfield
Vallejo Existing Mokelumne Aqueducts San Rafael Stockton Concord Date Saved: 12/26/2014
Proposed Mokelumne Oakland Aqueducts Tunnel San Alameda Francisco /
0 10 20
Modesto Miles
TITLE: Fremont Location Map
PROJECT: Mokelumne Aqueducts Delta Tunnel Study - TM5
San Jose DATA REFERENCE(S): Coordinate System: NAD 1983 2011 California Teale Albers Projection: Albers Metro Datum: NAD 1983 2011 Area Units: Meter
FIGURE: Sources: Esri, USGS, NOAA 1-1 Document Path: \\Usboi1s02\gis\_Projects\EBMUD_Mokelumne\_MXDs\TM5\MWH_SiteMap_TM5_11x17_Landscape_12262014.mxd
IndianIndian Woodward Island Slough Island Roberts San Joaquin IslandIsland River Trapper River Slough
Bixler Holt
Jones Tract Jones Tract Orwood Orwood Old Middle West East West East River River
TITLE: LEGEND !´ Boring (Multiple Consultants) Proposed Mokelumne Aqueduct Tunnel with Highway Date Saved: 12/26/2014 Site Plan Shallow Buried Concept as an Alternative ! PROJECT: A BDCP Boring Major Road Mokelumne Aqueducts Delta Tunnel Study - TM5 Existing Mokelumne Aqueduct Alignment ! DATA REFERENCE(S): Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet A CPT Local Road Projection: Lambert Conformal Conic Datum: North American 1983 BDCP Approximate Proposed Alignment ² Units: Foot US County Interstate 0 1 2 Miles FIGURE 1-2 Path: \\Usboi1s02\gis\_Projects\EBMUD_Mokelumne\_MXDs\TM5\MWH_Shallow_Pipeline_Alt_TM5_22x34_Landsc_12_26_14.mxd LEGEND
/ A! CPT Shallow Pipeline III Reach Number River Crossing V Reach Number Shallow Buried on Piles River Crossing (Twin Microtunnels)
Notes:
1. Stationing is approximate. 2. Horizontal: 1 inch = 2,000 ft (when printed at actual size) /
Source: CWDD, 1981 ESA, 1992 Treadwell & Rollo, 2010 URS, 2007 LiDAR Data from DWR, 2007
0 2,000 4,000 6,000 8,000
Feet
TITLE:
Buried Pipeline Alternative - Layout of Reaches
PROJECT: Mokelumne Aqueducts Delta Tunnel Study - TM5
DRAWING REFERENCE(S): Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet Horizontal and Vertical Units: Foot US
Updated: 12/26/2014
FIGURE 3-1
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APPENDIX A – OPINION OF PROBABLE CONSTRUCTION COST
3/17/15 MWH DC 1/6/2015 MOKELUMNE Pipeline on Piles Open Cut
Currency: USD-United States
Grand Total Price: $ 959,670,000 Item Description Quantity UOM Unit Price Total Price Comments
Launch/Recieving Shafts for MICRO Tunnels 42ft ID 135 ft exc 8 EA $58,015.83 $58,282,180 1 Water Control for Shaft & Tunnel Construction 8 EA $500,000.00 $4,000,000 2 Shaft Site Set Up 8 EA $450,000.00 $3,600,000 3 Shaft Starter Wall for Slurry Trench 200 CY $700.00 $140,000 4 Slurry Wall 3 ft Thick at Perimeter 165ft depth 20,724 CY $1,045.00 $21,656,580 ball park Quote 5 Excavate Shaft 55,390 CY $200.00 $11,078,000 6 Concrete Tremie Slab Shaft Base Concrete 3,282 CY $500.00 $1,641,000 7 Jet Grouting 13,540 CY $400.00 $5,416,000 8 Pipe Encasement Concrete 15,232 CY $500.00 $7,616,000 9 Shaft Structural Backfill 33,552 CY $50.00 $1,677,600 10 Install Shaft Piping 87 inch Steel Pipe 2,160 VF $75.00 $162,000 11 Demolish 5ft of Slurry Wall 1,248 CY $150.00 $187,200 12 Dispose of Excavated Material 55,390 CY $20.00 $1,107,800 MICRO Tunnel 7.25 Diameter 4 EA $12,570,000 1 Jack 87in Steel Pipe 8,200 LF $1,500.00 $12,300,000 2 Dispose of Excavated Material 13,500 CY $20.00 $270,000
Open Cut Pipeline $241,052,948 1 Trench Excavation 83,425 LF 475,831 CY $12.00 $5,709,972 2 Bent Excavation 1,355,193 CY $12.00 $16,262,316 3 Piling 16,685 Each 1,668,500 LF $50.00 $83,425,000 4 Concrete Pile Bents 133,480 CY $550.00 $73,414,000 5 Install 87 in T=.75 inch Steel Pipeline & Weld 166,850 LF $65.00 $10,845,250 6 Backfill Trench P Gravel 438,000 CY $45.00 $19,710,000 7 Native Backfill 986,694 CY $15.00 $14,800,410 8 Dispose of Excavated Material 844,300 BCY $20.00 $16,886,000
Purchased Materials $175,616,774 1 Pipe Bedding Materials Land 60 CY $15.00 $900 2 Concrete Purchase 136,762 CY $125.00 $17,095,250 3 P Gravel Backfill in Trenches 438,000 CY $12.00 $5,256,000 4 Granular Backfill in Shafts 33,552 CY $12.00 $402,624 5 87 in T=.75 inch Steel Pipeline 166,850 LF $900.00 $150,165,000 6 87 in T=.75 inch Steel Pipeline in shaft 1,080 LF $900.00 $972,000 7 87 in T=.75 inch Steel Pipeline Elbows 32 EA $18,000.00 $576,000 8 87 in x 69 inch x 69 inch Wye T=.75 inch Steel Pipeline 2 EA $35,000.00 $70,000 9 87 in x 69 inch T=.75 inch Steel Pipeline Reducer 4 EA $9,000.00 $36,000 10 Tie Downs 4,172 EA $250.00 $1,043,000 Tie in Land Work from Shaft Number 1 $88,250 1 Excavate Lay & Backfill 87in Pipe 330 LF $65.00 $21,450 2 Weld 87 in T=.75 inch Pipeline 18 JT $2,600.00 $46,800 3 Weld 87 in Fittings 8 JT $2,500.00 $20,000
Running Subtotal: $487,610,152
Mobilization/Field Oversight Expenses $ 87,769,827 1 Contractor General Conditions (Prime) 1 ls 18% $ 87,769,827
Unlisted Items Cost Allowance $57,537,998 1 Unlisted Items Allowance 1 ls 10% $57,537,998
Running Subtotal: $632,917,977
Markups $ 166,804,346 1 Prime Contractor OH&P 1 ls 15.0% $ 94,937,697 2 Contractor Insurance Program 1 ls 1.5% $ 10,917,835 3 Taxes on Matls 1 ls 8.25% $ 60,948,814 4 Escalation 1 ls 0.0% $ - not included
Running Subtotal: $ 799,722,323
Project Administration & Management $159,944,465 1 Construction Oversight & Mgt 1 ls 0% $0 not included 2 Engineering 1 ls 0% $0 not included 3 Permitting/Planning/Procurement 1 ls 0% $0 not included 4 Scope Contingency/Market Conditions 1 ls 20% $159,944,465 5 Construction Contingency/Management Reserve 1 ls 0% $0 not included
Grand Total: $959,666,788 Total w/ Contingency
Cost Range: $767,730,000 $1,247,570,000 Per AACE cost estimate guidelines 20% 30% This OPCC is classified as a Class 5 cost estimate per AACE guidelines. Stated accuracy range Pricing basis = 1st Qtr 2015, escalation to midpoint of construction is not included. Pricing assumes competitive market conditions at time of tender (+3 bidders/trade). Owner soft costs and project management expenses excluded.
Estimating Disclaimer - Engineer's Opinion of Probable Construction Costs
The estimate of costs shown and any resulting conclusions on the project financial, economic feasibility or funding requirements have been prepared from guidance in the project evaluation and implementation from the information available at the time the estimate was prepared. The final Costs of the project and resulting feasibility will depend on actual labor and material costs, competitive market conditions and other variable factors. Accordingly, the final project costs may vary from the estimate. Project feasibility, benefit/cost analysis, and risk must be reviewed prior to making specific funding decisions and establishment of the project budget.
AACE International CLASS 5 Cost Estimate – Class 5 estimates are generally prepared based on very limited information, and subsequently have wide accuracy ranges. Typically, engineering is from 2% to 10% complete. They are often prepared for strategic planning purposes, market studies, assessment of viability, project location studies, and long range capital planning. Virtually all Class 5 estimates use stochastic estimating methods such as cost curves, capacity factors, and other parametric techniques. Expected accuracy ranges are from –20% to –50% on the low side and +30% to 100% on the high side, depending on technological complexity of the project, appropriate reference information, and the inclusion of an appropriate contingency determination. Ranges could exceed those shown in unusual circumstances.(AACE International Recommended Practices and Standards).
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APPENDIX B – CLASSES OF COST ESTIMATES AS DEFINED BY AACE
Page 31 of 73 3/1715 APPENDIX B
CLASSES OF COST ESTIMATES AS DEFINED BY ASSOCIATION FOR THE ADVANCEMENT OF COST ENGINEERING (AACE)
AACE International CLASS 5 Cost Estimate – Class 5 estimates are generally prepared based on very limited information, and subsequently have wide accuracy ranges. Typically, engineering is from 2% to 10% complete. They are often prepared for strategic planning purposes, market studies, assessment of viability, project location studies, and long range capital planning. Virtually all Class 5 estimates use stochastic estimating methods such as cost curves, capacity factors, and other parametric techniques. Expected accuracy ranges are from –20% to –50% on the low side and +30% to 100% on the high side, depending on technological complexity of the project, appropriate reference information, and the inclusion of an appropriate contingency determination. Ranges could exceed those shown in unusual circumstances.
AACE International CLASS 4 Cost Estimate – Class 4 estimates are generally prepared based on limited information and subsequently have fairly wide accuracy ranges. Typically, engineering is 10% to 40% complete. They are typically used for project screening, determination of feasibility, concept evaluation, and preliminary budget approval. Virtually all Class 4 estimates use stochastic estimating methods such as cost curves, capacity factors, and other parametric and modeling techniques. Expected accuracy ranges are from –15% to –30% on the low side and +20% to 50% on the high side, depending on the technological complexity of the project, appropriate reference information, and the inclusion of an appropriate contingency determination. Ranges could exceed those shown in unusual circumstances.
AACE International CLASS 3 Cost Estimate - Class 3 estimates are generally prepared to form the basis for budget authorization, appropriation, and/or funding. Typically engineering is from 10% to 40% complete, and would comprise a minimum of process flow diagrams, utility flow diagrams, preliminary piping and instrumentation diagrams, plot plan, developed layout drawings, and essentially complete engineered process and utility equipment lists. They are typically prepared to support full project funding requests, and become the first of the project phase "control estimates" against which all actual costs and resources will be monitored for variation to budget. Most Class 3 estimates involve more deterministic estimating methods than stochastic methods. Typical accuracy ranges for Class 3 estimates are from +/- 10% to 30% (sometimes higher), depending on the technological complexity of the project, appropriate reference information, and the inclusion of an appropriate contingency determination.
AACE International CLASS 2 Cost Estimate – Class 2 estimates are generally prepared to form a detailed control baseline against which all project work is monitored in terms of cost and progress control. For contractors, this class of estimate is often used as the “bid” estimate to establish contract value. Typically, engineering is from 30% to 70% complete, and would comprise at a minimum of the following: process flow diagrams, utility flow diagrams, preliminary piping and instrumentation diagrams, heat and material balances, final plot plan, final layout drawings, complete engineered process and utility equipment lists, single line diagrams for electrical, electrical equipment, and motor schedules, vendor quotations, detailed project execution plans, resourcing and work force plans, etc. Class 2 estimates always involve a high degree of deterministic estimating methods often involving thousands of unit cost line items. Typical accuracy ranges for Class 2 estimates are –5% to –15% on the low side, and +5 to +20% on the high side, depending on the technological complexity of the project.
AACE International CLASS 1 Cost Estimate – Class 1 estimates are generally prepared for discrete parts or sections of the total project rather than generating this level of detail for the entire project. These estimates may be prepared for to determine a fair price or bid check to evaluate claims and disputes. Typically engineering is 50% to 100% complete and would comprise of virtually all engineering and design documentation for the project and complete execution and commissioning plans. Expected accuracy ranges are –3% to –10% on the low side to +3% to + 15% on the high side depending on the technological complexity of the project, appropriate reference information and appropriate contingency determination.