Under the River and to the Camp: Allstate Boring All-Stars Complete Horizontal & Vertical Pipe Rams

Sometimes trenchless is about choices.  What method? What tool? What size?  How long? How much? How little?  Contractors with creativity, knowledge and vision don’t see those choices as challenges, but more as opportunities. Allstate Boring, Bakersfield, Calif., is exactly that type of contractor. 

On a recent project in Kern County California, the utility boring contractor demonstrated how creativity, skill with multiple trenchless methods, and the ability to react quickly can overcome challenges and result in a successful project.

Allstate Boring President Brian Sherrell explained, “This was really a case of, ‘The contractor had all the tools that he needed to do the job, but he wasn’t sure what tool it was going to take.’  We were subcontracted to install a 30-inch horizontal casing under a river, about 275 feet in length. We started out auger boring it, and we got 73 feet in and hit an underground river. Once we hit the underground river and the flowing soils, we had to make a quick decision and convert the installation to another method. We choose pipe ramming.”

According to Pipe Ramming Specialist Rick Melvin with trenchless equipment manufacturer TT Technologies, Aurora, Ill., the transition from one method to the next was perfectly executed.  He said, “Making that quick decision to switch to ramming helped save the project, but that wasn’t the only bit of creativity and ramming on this project!”

To complete the install under the river, Allstate Boring used an 18-inch diameter Grundoram Goliath pneumatic pipe rammer from TT Technologies. The installation of the 30-inch casing was a key component to supplying a reliable water source for the camp/park recreation area in Kern County. A vertical pipe ram of a 72-inch casing, on the other side of the river to facilitate a receiving pit, made the completion of this possible and highlighted Allstate Boring’s ramming skill.

Camp Okihi Needs Water

Camp Okihi in Kern County needed water. While the park was apparently permitted to draw water from the river as needed, that situation was both unpredictable and unreliable. Kern County was interested in enhancing the park and bringing it back to life. According to Sherrell, the park features a variety of wildlife including goats, turkeys, and other wildlife that appeal to school-age children. However, they needed to get on a reliable water source.

Sherrell said, “Cal Water owns a water facility across the river, so Kern County needed to get an eight-inch water line from that water tie-in point, under the river, and then to the camp so that the camp has a stable water supply for the animals, plants, and the flowers; everything that the elementary school kids are going to come out and enjoy. So, the plan was to install a casing under the Kern River insert a new 8-inch ductile iron water main and then on the other side of the river, bring that line up vertically, creating the water access the park needed.”

The general contractor for the project was RLH Fire Protection, Bakersfield, Calif. The multifaceted contractor subcontracted Allstate Boring to install the casings for the project. 

Allstate Boring Background

Allstate Boring is a family owned, licensed contractor located in the heart of California, Bakersfield.  Since 1997, Allstate Boring has been a leader in the use of trenchless construction. The utility contractor specializes in trenchless bores ranging in sizes from 4 to 72 inches in diameter. Over the past 28 years Allstate Boring has completed countless boring projects, including diameters up to 72-inch and lengths up to 725-foot casing installation.  

Allstate Boring utilizes electronically controlled boring machines and pilot tubes as well as hydraulic steering heads. The contractor can install all types of carrier pipes including ductile iron, PVC, CLMC, HDPE, and more.  

Above all, Allstate Boring is a safety conscious company and has a strong history of providing a safe work environment for its employees. Allstate Boring’s commitment to safety was evident on the Kern River project.

Switching Gears

RLH Fire Protection established a significant launch pit on the north side of the river to facilitate the installation of a 30-inch casing. The Allstate Boring crew started out with auger boring the casing under the river because the ground was a very dense clay. Crews got the casing aligned properly and started boring. The plan was to steer the casing using a bottom window or “shoe,” but that plan changed.

Sherrell said, “We went in [the casing] at 20 feet to make adjustments to the casing alignment and then we went in at 40 feet, and we were going to go in at 80 and make a correction. But we couldn’t do that. We basically hit an underground river at 73 feet. So, we were never able to go back in the pipe again due to water flow. Luckily, the right and left alignment was perfect, and we just had the joint barely pitched up a little bit more than what we wanted. But we had to be satisfied with that.”

From there, the decision to pipe ram the remaining 200 feet of casing was made. Allstate Boring crews brought in the 18-inch diameter Grundoram Goliath and utilized the auger tracks as a ramming platform.

According to Sherrell, safety was a top concern.  He said, “We didn’t want to access the front of the pipe. We’re trying to keep our employees out of harm’s way. You don’t want to be crawling in a casing underneath the river. When we went to go clean out after the job was over with, we had to go in and get those bigger rocks, bigger boulders. But it was when the job was safe to do it.”

Crews connected the 18-inch diameter pipe rammer to the 30-inch casing through standard ramming gear, a series of tapered, locking ram cones. During ramming, the casing gradually climbed. Sherrell said, “Every joint went up a little bit more, like .05% to .10% of grade per joint is all we gained while we were pipe ramming. So, it was a very nice, slow, gradual climb that we got in the remaining 205 feet.”

Approximate drive times per 20-foot casing ranged between an hour and an hour and a half, depending on how firm the soil or how rocky the soil was. Sherrell was able to track the progress and direction of the casing closely using Casing Compass technology from PLG Technologies, Bakersfield, Ca., which played an important role in the horizontal casing install and determining the location for the 72-inch ram.

Casing Compass

The patent pending Casing Compass system is used to remotely monitor the position of a casing bore. It is welded to the top of the lead casing and features a calibrated sensor inside of the unit that provides real time data on the pipe location and the direction as it is being installed. By taking regular readings, grade can be determined and monitored.

Sherrell said, “Dealing with groundwater becomes overwhelming. So, the more groundwater you have, the more you want to do things remotely, the more you want to find out information remotely. That’s what the Casing Compass did for us. We were able to know where grade was. There was a requirement on the job that the engineering firm and the agency gave us that we had 15 feet of clearance from the low part of the river to the top of the casing.

“We were able to build a spreadsheet with the starting elevation and then input the Casing Compass pitch readings on 10-foot centers. The spreadsheet calculates the elevation change from the Casing Compass reading and distance traveled. So, we were able to prove that we had 15 foot of clearance underneath the low part of the river at 170 feet.”

That information also allowed Allstate Boring to know what the elevation of the top of the casing was at the receiving pit area. Then they were able to determine how much of the 72-inch casing they had to drive in the ground.

Going Vertical

For the vertical installation, cost effectiveness was a driving factor. The 72-inch casing would serve as an extremely capable and affordable receiving pit. Sherrell explained, “For creation of a receiving pit on the other side of the river, we were looking at somewhere near a quarter million dollars’ worth of engineered shoring, digging, clam shelling, excavation, with engineered square or rectangular shoring. Well, you know, as I do, that a round structure is much stronger. And can take the loads from the earth a lot better than something that’s square or rectangle. So, it requires less metal thickness. At today’s steel prices, we were able to shore it without it having to be an extremely expensive rental item. We got to buy the 72-inch casing, and then we were able to drive it in.”

Allstate Boring used a unique rammer configuration to drive the 72-inch vertical. Crews attached the rammer to a 48-inch casing using standard ram gear.  That configuration was welded onto a three-inch thick 8-foot by 8-foot plate. The that was welded to the top of the 72-inch casing.

Melvin said, “This was a unique and economical approach to vertical ramming. The Allstate crews had just enough of transfer of energy from the rammer to the casing to complete the installation.”

Over two days of ramming, crews were able to install 19 feet of vertical casing. According to Sherrell, drive time was probably four hours total, after aligning everything.

He said, “After knowing where the end of our casing was, we were able to drive the 72-inch in over the top of the 30-inch and create a safe working environment at the connected casings. We were able to create a working environment that could get down inside of and plumb up the eight-inch waterline, the eight-inch ductile iron waterline that was going through the 30-inch casing.”

Allstate Boring contracted the cleanout of the 72-inch casing. After all the material was removed, crews pushed in the 8-inch ductile iron pipe to where the 30-inch and the 72-inch casings met on the west side of the river. A 90-degree fitting was then bolted on, and a vertical ductile iron pipe connect, reaching to ground level.

The 72-inch casing was then removed. At the same time, a control low-strength material grout was pumped in. The general contractor made all the final connections.

Melvin said, “This was one of those projects that kind of leaves you in awe. There was a level of creativity and skill that truly defines a great contractor.  Allstate Boring falls into that category for sure.”