Miami-Dade s Water Main Government Cut Replacement Project

Transcription

1 North American Society for Trenchless Technology (NASTT) NASTT s 2013 No-Dig Show Sacramento, California March 3-7, 2013 Paper MA-T2-02 Miami-Dade s Water Main Government Cut Replacement Project Glenn Boyce, PhD, PE 1, Steve Mancini 2, Craig Camp 3, Rick Zavitz 4, Orlando Castro, PE 5, and Eduardo Vega, PE 6 1 Jacobs Associates, Walnut Creek, CA, USA 2 Ric-Man Construction, Detroit, MI, USA 3 Hatch Mott MacDonald, San Diego, CA, USA 4 Mears Group, Billings, MT, USA 5 Hazen & Sawyer, Hollywood, FL, USA 6 Miami-Dade County Water and Sewer Department, Miami, FL, USA ABSTRACT: Miami-Dade Water and Sewer Department (MDWASD) owns and operates a 20-inch (510 mm) ductile iron water main that transmits water from the mainland to Fisher Island and the Port of Miami for distribution. The water main crosses Fisherman s Channel with a top-of-pipe elevation of El feet (-15.9 m) (NGVD 29) conflicts with the Federal Navigational Dredging Project, which proposes to widen and deepen the channel to El. -50 feet (-15 m) (NGVD 29), increasing the harbor s capacity. To accommodate the aggressive US Army Corps of Engineers dredging project schedule, the replacement water main must be designed, constructed, and commissioned prior to the start of channel deepening. The Ric-Man Construction Design-Build Team s alternate design replaced the existing 20-inch water main with 24- inch ID/30-inch OD (610 mm/760 mm) high density polyethylene (HDPE) pipe using horizontal directional drilling (HDD) beneath Fisherman's Channel. The water main was constructed between the east end of the Port of Miami and the Fisher Island ferry staging area. The 1,580-foot-long (482 m) crossing was completed in October INTRODUCTION The Miami-Dade Water and Sewer Department (MDWASD) is undertaking a project to replace two existing utility mains under the navigation channels of Biscayne Bay. The first is an existing 20-inch-diameter water main under Fisherman s Channel between the Port of Miami on Dodge Island and Fisher Island. The second is an existing 54- inch (1,370 mm) sewer force main under Government Cut between Fisher Island and a location in the water south of the City of Miami Beach. Both of these utilities are in conflict with the proposed Port of Miami Federal Navigational Dredging Project, which will deepen and widen the harbor and channels beginning in The Port of Miami Federal Navigational Dredging Project will expand the Port of Miami by dredging the bay to allow new, larger cargo ships to enter the port. This project is related to the New Panamax project to be completed by 2014 that involves a major expansion of the Panama Canal. The port, which is currently 42 feet (13 m) deep, will have to be dredged to 50 feet (15 m) in depth to allow the new Super Post Panamax megaships to enter. The dredging project along with port facility improvements will make the Port of Miami capable of berthing even the second largest container vessels in the world, the Maersk Triple E Class, which will have a draught of 48 feet (14.6 m) and will be nearly 200 feet wide (61 m). Paper MA-T

2 The existing 20-inch-diameter water main under Fisherman s Channel is part of a loop that runs through downtown Miami, the Port of Miami, Fisher Island, and Virginia Key. The existing portion of the 20-inch main was originally conceived to be replaced with two pipes inside of a 850-foot-long (259 m) microtunneled casing at a depth of approximately 90 feet (27 m) below mean sea level (see Figures 1 and 2). One pipe will be a 24-inch-diameter main that will provide primary water service in place of the existing 20-inch-diameter pipe. The second pipe will be a 12- inch (305 mm) supplementary water service that is capable of modification at a later date to provide reclaimed water. Figure 1. Microtunneled water main alignment between the Port of Miami (right) and Fisher Island (left). Figure 2. Proposed cross section of the water main and reclaimed line inside of the 60-inch-diameter (1,525 mm) casing. The microtunnel boring machine (MTBM) launching shaft and the connection point with a new bidirectional flow meter would have been located in the Port of Miami on Dodge Island. The MTBM retrieval and the connection point to the existing service main would have been on Fisher Island. The replacement water mains were to be designed, Paper MA-T

3 constructed, tested, and placed into service prior to decommissioning the existing 20-inch-diameter water main, which will be properly abandoned and removed during the dredging operation. In the fall of 2010, MDWASD solicited proposals from design-build teams to replace the water and sewer mains. MDWASD received five proposals and conducted interviews. The design-build team of Ric-Man Construction with Hazen & Sawyer was selected. The design-build teams were required to provide base bids for the replacement water and sewer mains using microtunneling technology. The teams were allowed to include bid alternates to the base bid at no cost to the MDWASD. The Ric-Man Construction Design-Build Team included a bid alternate to use horizontal directional drilling (HDD) to replace the water mains. 2 ALIGNMENT AND CONSTRUCTION METHOD CHANGES In the proposal to MDWASD, the Ric-Man Construction Design-Build Team included a bid alternate to install the new water main using HDD that placed the entry point of the HDD on the Port of Miami. The entry point needed to be set back to make sure sufficient depth was obtained so the HDD alignment could get under the steel sheeting and piling seawall that defined the loading and crane areas of the port. A perpendicular crossing of the Fisherman s Channel also meant the HDD s exit point would extend further onto Fisher Island to get the depth needed to cross under the steel sheeting and piling seawall used to establish the north boundary of Fisher Island. While the original bid alternate proposal was well received by the MDWASD, opposition quickly surfaced from the Port of Miami and the Fisher Island s Home Owners Association. To understand the issues, you need to understand the amount of business done at the Port of Miami and the history of Fisher Island. The Port of Miami is recognized as the Cruise Capital of the World and Cargo Gateway of the Americas. It has retained its status as the number one cruise/passenger port in the world for well over two decades, accommodating the largest cruise ships in the world and the operations of such major cruise lines as Carnival, Royal Caribbean, and Norwegian Cruise Line. As the Cargo Gateway of the Americas, the port primarily handles containerized cargo with small amounts of break bulk, vehicles, and industrial equipment. It is the largest container port in the state of Florida and the ninth largest in the United States. As a world-class port, the Port of Miami is among an elite group of ports in the world that cater to both cruise ships and containerized cargo. The Port of Miami is an important contributor to the local South Florida and state economies. Over four million cruise passengers go through the Port each year. In addition, 7.4 million tons of cargo and over 1 million 20-foot equivalent units (TEU) of intermodal container traffic move through the seaport each year. This combination of cruise and cargo activities supports approximately 176,000 jobs, and has an economic impact in Miami-Dade County of over $17 billion, $14 billion of which is generated by its cargo operations. Fisher Island is a neighborhood of metropolitan Miami, Florida, located on a barrier island. Fisher Island has the highest per capita income in the United States. The island has only 722 residences, which consists of single family houses and condominiums. Named for automotive parts pioneer and beach real estate developer Carl G. Fisher, who once owned it, Fisher Island is 3 miles (4.8 km) off shore. No road or causeway connects to the island, which is accessible by private boat or ferry. Once a one-family island home of the Vanderbilts, and later several other millionaires, it was sold for development in the 1960s. After years of legal battles and changes in ownership, further development on the island was finally started in the 1980s, with architecture matching the original 1920s Spanish-style mansions. Although no longer a one-family island, Fisher Island still remains inaccessible to the public and uninvited guests, and is as exclusive by modern standards as it was in the days of the Vanderbilts, providing similar refuge and retreat for its residents. The island contains mansions, a hotel, several apartment buildings, an observatory, and a private marina. Boris Becker, Oprah Winfrey, and Mel Brooks are among the celebrities with homes on the island. After discussions with the Port of Miami and Fisher Island, alternative entry and exit locations were identified for use by MDWASD and the Ric-Man Construction Design-Build Team. The resulting new HDD alignment is shown in Figure 3. The entry point for the HDD was moved further north of the MTBM launching shaft, into the Longshoremen s parking lot. From the parking lot, a 15 degree entry angle made it easier to meet the Port of Paper MA-T

4 Miami s requirement of being 102 feet (31 m) below grade to a top-of-pipe elevation of -90 feet (-27 m) (NGVD 29). This depth was required in order to avoid the steel sheeting and piling along the Port s seawall. The HDD would reach a maximum depth of 97.4 feet (29.7 m) below the bottom of Fisherman s Channel, a top-of-pipe elevation of feet ( m) (NGVD 29). The new horizontal alignment would also consist of two horizontal curves with a 1,650-foot (503 m) radius of curvature to avoid cargo ships and gantry cranes areas. Figure 3. Alternate HDD water main alignment between the Port of Miami and Fisher Island (red dotted line); pipe string layout (purple dotted line) On Fisher Island, the Home Owners Association offered up use of the Corporation Work Area, where the commercial ferry and delivery trucks arrive and depart. The area was already screened by landscaping and vegetation to minimize the visual impact to the residents. The peanut shaped work area was set back far enough from the water s edge to allow room for the HDD exit angle to reach the surface. The HDD did extend under the golf course s man-made lake, but the lake is relatively shallow and did not affect the vertical alignment. To accommodate the pipe string for pullback, the pipe string needed to turn 90 degrees from the exit point and then was laid out in a U shape around the boundary of the corporate work area. The pipe string layout is shown as the purple dashed line in Figure 3 and in the aerial photograph in Figure 4. The vertical HDD alignment for the crossing is shown in Figure 5. With the increased crossing length and a need to minimize impacts to the Port of Miami and Fisher Island, the MDWASD elected to eliminate the installation of the 12-inch-diameter supplemental water main. The final HDD installation was 24-inch ID/30-inch OD HDPE pipeline. Paper MA-T

5 Figure 4. Working space on Fisher Island with HDPE pipe assembled for pull back. 3 GEOTECHNICAL CONDITIONS MDWASD hired AECOM as its designer to assemble the design-build criteria documents. The AECOM team undertook a site-specific subsurface exploration and testing program. The program was divided into four phases: Phase I: Desk Study conducted during preliminary design to research and compile existing subsurface data in the project vicinity. Phase II: Subsurface explorations consisting of seven borings and associated laboratory testing, completed by Geosol in Phase III: Geophysical survey consisting of bathymetry, seismic reflection, and seismic refraction, completed by Technos in 2009 and Robayna & Associates in Phase IV: Exploration program (supplemental program) consisting of 12 borings and laboratory testing, completed by Geosol in Three land borings were drilled for the water main crossing: B-2, B-7, and B-11. The borehole data were supplemented with: Geologic maps and publications, sinkhole databases, earthquake hazard maps Historical maps (Sanborn) of the Miami area Geotechnical reports for the Government Cut Microtunnel Project, prepared by LAW in 1997 Geotechnical reports for the FPL Proposed 69 kv and 138 kv FPL Transmission Lines, prepared by PSI in 2003 Geotechnical reports for the Port of Miami Project, prepared by PSI in 2003, 2005, and 2006 The geological setting for the water main crossing basically consists of four units: Artificial Fill (Af), Miami Formation (Qm), Fort Thompson (FT), and Tamiami Formation (TT). The units are subdivided by layers of sand and limestone. Table 1 provides a summary of the geological units, the subunits, and their typical thicknesses. Of note is the presence of sand layers sandwiched by limestone rock above and below. The limestone is also porous, with numerous voids and cavities, most of which are filled with sands and silts. Paper MA-T

6 Table 1. Geological units in the Miami/Government Cut Area. Geological Unit Description Symbol Thickness, ft (m) Artificial Fill SILTS to fine SAND with LIMESTONE rock fragments Af 0 to 4 (0 1.2 m) Miami Soft to medium marine LIMESTONE Qm 0 to 18 (0 5.5 m) Formation Fort Thompson Loose to medium dense fine SAND FT-1 0 to 25 (0 7.6 m) Medium to hard sandy LIMESTONE FT-2 0 to 17 (0 5.2 m) Hard to very hard freshwater LIMESTONE FT-3 10 to 32 ( m) Medium to hard shelly LIMESTONE FT-4 0 to 20 (0 6.1 m) Loose to medium SAND FT-5 2 to 25 ( m) Medium hard porous shelly LIMESTONE FT-6 6 to 36 ( m) Tamiami Medium dense to very dense SAND TT-1 0 to 15 (0 4.6 m) Formation Soft to hard porous to vuggy LIMESTONE TT-2 Unknown Figure 5. Vertical profile for the HDD crossing between the Port of Miami and Fisher Island (modified from AECOM, 2010). The geotechnical profile for the proposed HDD alignment and the interpreted geologic conditions between borings are presented in Figure 5 (AECOM, 2010) (symbols for units provided in Table 1). Based on the heterogeneous nature of all the ground anticipated to be encountered along the alignment, the face conditions should be considered as mixed face (soil/bedrock) conditions. Engineering characteristics and properties will differ markedly between some strata groups such that ground behavior will vary as each strata group is excavated. The main construction risks associated with the formations along the alignment consist of: Mixed-face conditions with competent zones embedded in softer materials Sudden and large-scale water inflow from karst features and zones Flowing sands Rock mass with frequently changing deformation and hydraulic characteristics 4 PILOT HOLE DRILLING AND REAMING The Ric-Man Construction Team hired the Mears Group out of Rosebush, Michigan, as the HDD subcontractor for the crossing. Mears mobilized a 1,000,000-lbf (463,600 kg) rig and set it up in the Longshoreman s Parking Lot within the Port of Miami. The drill rig is shown in Figure 6. Paper MA-T

7 Figure 6. Mears Group s HDD Drill Rig setup at the Port of Miami. A 42-inch-diameter (1,065 mm) surface casing was installed within the artificial fill at the Port of Miami. The entry angle of rig was set at 15 degrees so as to quickly obtain the pilot hole depth in order to get under the Port of Miami seawall. Mears started drilling on Friday, August 12, The initial drilling went quickly. The drill rods were on average about 31 feet long (94 m). The 1,581-foot-long (482 m) crossing would take 51 drill rods to complete. Drilling advanced at about 200 feet (61 m) per day over the weekend. During the drilling, drilling mud would be lost on occasion into the formation with no return of cuttings. The drilling mud would return to the hole. This mud was continuously mixed and added to the hole. By the late afternoon on Tuesday, August 16, the tip distance from the rig was 933 feet (284 m), or 30 rods (as shown in Figure 5). The leading edge was in the Tamiami Formation, which is known to contain large voids and cavities within the limestone. In the late afternoon, drilling mud was lost and the drill rods would not advance. The retrieval of the drill rods was started. Nine rods were tripped out on August 16. On returning to the site on Wednesday, August 17, the drill rods were hung up in the hole. Mears made various efforts to free up the rods. Eventually 11 rods were retrieved, but Mears found the drill rod was broken off. Left in the drill hole were 11 drill rods, including the gyroscope and mud motor. On August 18, Mears began fishing for the fish left in the hole and made contact. To add to the excitement, hurricane season starts in South Florida as early as August and continues through October. On the evening of August 20, a large low pressure area became organized enough to be classified as Tropical Storm Irene. Early on August 22, Irene strengthened into a Category 1 hurricane, with winds of 75 mph (121 km/h), becoming the first official hurricane of the 2011 season. Early on August 24, Irene became a Category 3 major hurricane, with winds of 120 mph (193 km/h). Irene went through a partial replacement cycle, which weakened it slightly and caused it to miss hitting Florida directly. On August 27, Hurricane Irene made landfall on Cape Lookout, North Carolina, and then later made landfall in New Jersey. Damage from Hurricane Irene totaled $19 billion, making it the fifth costliest hurricane in the Atlantic basin. Mears worked through the storm as it passed offshore and made multiple attempts at catching the fish (drill rods left in the hole). They added an additional 83 feet (25 m) of 12-inch-diameter (305 mm) casing to the drill hole. On Friday, August 26, Mears caught and landed a 263-foot-long (80 m) fish, with gyroscope and mud motor. Everyone on the project was happy and had a new fish story to tell. Paper MA-T

8 Mears resumed drilling the pilot hole on August 30. The pilot hole surfaced on Fisher Island on September 2. Seen in Figure 7, the pilot hole was on line and missed the designated end point by only a few feet. Figure 7. Hole-through of the pilot hole on Fisher Island on September 2. To enlarge the pilot hole, Mears elected to attach a tandem 26-inch and 42-inch (660/1,065 mm) reamer to the drill rods. The process was started by attaching the tandem on the drill rig side and pushing with a forward ream (see Figure 8). Fisher Island was outfitted with an excavator to pull the drill rods. The tandem system was able to excavate about 30 feet (9.1 m) before a second break occurred in the drill rods. The second break occurred on the Fisher Island side, about 270 feet (82 m) in. This time, since the drill hole was completed, the drill rods remained in contact. The tandem reamer was retracted, and drill rods were added to push the broken joint out of the drill hole on the Fisher Island side. After a series of meetings, it was decided to divide the reaming pass into two passes. The pilot hole would be enlarged to 26 inches (660 mm) as the first reaming pass. The reamer would be set up on Fisher Island and reamed toward the Port of Miami. The drilling mud would be batched at the Port of Miami side, and the cuttings would be collected on the Fisher Island side. After completion of the first ream, the hole would be enlarged to 42 inches (1,065 mm) through a second reaming pass. The second ream would also be from Fisher Island toward the Port of Miami. Mears Group also elected to mobilize a second drill rig to Fisher Island to allow the two drill rigs to work in a push-pull combination. The second reaming attempt was going relatively smoothly until September 22, when the drill rods broke a third time. The break occurred with 242 feet (74 m) left, or about nine drill rods short of the Fisher Island side. As with the second break, the drill rods remained in contact. The reamer was retracted, and drill rods were added to push the broken joint out of the drill hole on the Fisher Island side. The third reaming attempt of the ream began on September 29 and by October 5 the drill hole was reamed out to 26 inches (660 mm). The final reaming pass was started on October 5 and completed without a problem on Friday, October 14. With the drilled hole reamed out to 42 inches (1,065 mm), the hole was swabbed and prepared for pullback. Paper MA-T

9 Figure 8. Tandem reamers used to increase the pilot hole to 26 inches and then 42 inches. 5 PULLBACK Pullback of the 24-inch ID, 30-inch OD HDPE pipe was scheduled on Sunday, October 16. The intent was to pull the 1,600-foot-long (488 m) pipe into the hole in one day. Sunday was the preferred day, as the commercial ferry did not run on that day and the parking lot was free for our use. The pullback was started at about 9 am (see Figure 9) in what turned out to be a very rainy and wet day. As shown in Figure 3, the pipe was strung around the outside edge of the parking lot. It took considerable effort to walk the pipe around the multiple curves and into the hole. The pipe was being filled with water as it entered the ground to help counter buoyancy. The drilled hole had been well prepared with the drilling mud to keep it open and slick. Pulling forces were monitored from the Port of Miami side. The pulling forces never exceeded more than 150,000 lbf (68,038 kgf) all day. The pullback was completed at 10 pm, about 13 hours after starting. The pull-in rate was about 120 feet (37 m) per hour. Figure 9. Pullback in process at the start (left) and then at midday (right). Paper MA-T

10 6 CONCLUSIONS The original design called for a 60-inch-diameter (1,525 mm), 850-foot-long (259 m) microtunneled steel casing to house the 24-inch (610 mm) replacement water main and a 12-inch (305 mm) reclaimed water line. The design actually used was an alternative proposed by the design-build team. Its use of HDD beneath Fisherman s Channel eliminated the construction of two shafts and allowed for the replacement water main to be completed in 2011 instead of The water main was constructed between the east end of the Port of Miami and the commercial ferry staging area on Fisher Island. The crossing length was extended to 1,581 feet and was completed entirely from land. Construction proceeded under extremely challenging circumstances and ground conditions. Pilot-hole drilling commenced in August 2011 during Hurricane Irene. The crossing was drilled through layers of the Fort Thompson limestone, which is considered vuggy with vugs and cavities up to 4 inches (100 mm) and mostly filled with sand or silt. The horizontal and vertical alignment was restricted by easements, power cables beneath the channel, the port seawall, and limited working space. Despite these challenges, the HDPE pipeline was pulled into place within a single day. The second phase of the project involves replacing the 54-inch-diameter (1,370 mm) force main between South Miami Beach and Fisher Island. A 72-inch-diameter (1,830 mm) steel casing will be installed by microtunneling, scheduled to begin in January REFERENCES AECOM Contract No. W-924 Volume 2, Book 1, Water Main Microtunnel Geotechnical Baseline Report, October, 64pp. Jacobs Associates Daily Inspection Reports. Miami-Dade Water Main Government Cut Replacement Project. Mears Group Daily Construction Reports. Miami-Dade Water Main Government Cut Replacement Project. Paper MA-T