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Chief Ladiga Trail Sinkholes

April 5, 2016 Webmaster

Report recommends $100,000 fix for Chief Ladiga Trail sinkholes

The Anniston Star – April 5, 2016
By Seth Boster, Anniston Star Staff Writer, sboster@annistonstar.com
View Original Article

Filling sinkholes that have closed a section of the Chief Ladiga Trail could cost upwards of $100,000, according to a report by an engineering firm.

And the money, the report says, wouldn’t prevent Mother Nature from striking again.

The report to the city of Jacksonville, obtained by The Star on Monday, recommends a concrete-filling process that the firm, Birmingham-based Building & Earth Sciences, estimates will cost between $100,000 and $150,000. The report includes three other restoration options but calls “grouting” the most feasible at the site, near Warren Drive in Weaver. Jacksonville in February committed $8,000 for Building & Earth’s services after portions of the city’s trail section, two spots about 100 feet apart, toppled into underground voids.

No option guarantees the trail from being swallowed again, the report states. It points even to a section south of the sinkholes as “a possible location for a future collapse,” based on a study that found subsurface conditions to be prime for sinking.

The other, less-detailed options listed in the firm’s report are: excavating and backfilling the sinkholes with rock, clay and synthetic material; leaving the sinkholes be and building the trail around them; or forming a bridge-like structure over them. The report didn’t include costs for the other options. Jeff Cowen, a Building & Earth engineer who helped prepare the report, explained in a phone call Monday that those options could be less effective and more expensive than grouting.

Excavating and backfilling, Cowen said, is typically the “preferred method” in fixing sinkholes. He cautioned against that method in Jacksonville’s case, though: Considering the depth — engineers were able to drill 30 feet down but did testing that showed bedrock some 30 feet deeper — and considering the narrow, sloping area at the site, Cowen doubted the procedure would work.

Building the trail around the sinkholes, the report notes, would commit Jacksonville to acquiring additional right of way and to an extensive construction project.

And due to the site’s sinkhole-prone geography, Cowen noted that the newly-formed trail would be susceptible to the same fate of the current trail. A bridge might not be safe, either.

“These are very active. That’s what stands out about these,” Cowen said, speaking to the rapid growth of the sinkholes and their nearness to each other. “That could indicate, it probably does indicate, that both of these holes are related to the same features underneath that could bring into question everything between them.”??

Officials in Jacksonville on Monday were weighing the options. Mayor Johnny Smith said he flipped through Building & Earth’s 40-page report and wondered about chances.

“That’s the hardest question about this whole thing,” Smith said. “What are the chances of a permanent fix?”

The area, like much of north Alabama, is at risk because of the prevalence of limestone bedrock. Water can erode the rock, causing soil to seep down through the spaces.

Calhoun County Commissioner Lee Patterson has said the commission would dedicate resources along with Jacksonville to see the trail restored. Smith said the city was hoping for grant money but sounded doubtful of that coming. Weaver Mayor Wayne Willis told Smith that his city could provide non-financial resources, but otherwise, Smith said he had not heard offers of help from other municipalities along the 33-mile trail, stretching from Anniston up to Piedmont.

The sinkholes came six months after the Jacksonville City Council passed a current fiscal year budget anticipating a $300,000 shortfall.

“We talk about quality of life that we all strive for, and that trail is a big factor in that,” Smith said of the trail, which is popular with cyclists, runners and walkers and is a tourist attraction. “It’s important to us, no question.

“It’ll be tough,” he said of restoring the trail. “But we’ll figure it out. We’ll find a way.”

?Staff writer Seth Boster: 256-235-3562. On Twitter @SethBoster_Star.[/vc_column_text][/vc_column][/vc_row]

Power Play

February 26, 2014 Webmaster

It’s no secret that there is major activity in the U.S. power market these days. Despite the development of more energy efficient appliances and a new emphasis on conservation efforts, consumer demand for electricity continues to grow. As a result, utilities are constantly looking for new sources of energy generation like wind and biomass as well as more traditional sources like combined and single cycle natural gas turbine and clean coal generation. We’ve been actively involved in projects in all of these areas of energy generation in the last few years, including a number of current projects. These complex, schedule-driven projects often require us to provide our services in remote areas with sometimes harsh climate conditions.

George Hays, a project manager who leads many of our energy projects, has been working in Wisconsin this winter for a new utility client, updating an existing power plant scheduled to receive a SCR scrubber system in 2014-2015. Our work at this 405 megawatt gross output power plant consists of four CMT projects and one geotech project. Dry Sorbent Injection (DSI) and Activated Carbon Injection (ACI) are both needed to reduce emissions. The total project also includes the installation of an ammonia storage structure, unloading station, surrounding earthwork, crane pad geotechnical evaluation, crane pad construction, and east and west SCR foundation systems. Building & Earth has the responsibility for materials testing and construction inspections where needed. The DSI, ACI, crane pad, and SCR foundation projects are supported on deep cast auger piles. Inspections include the auger cast piles, reinforcing steel, structural steel, construction activities as directed, and field testing of the grout and structural concrete. We are working closely with the client’s QA section to provide assistance for inspection and construction documentation.

Our Louisville branch has been equally busy over the last year with several active projects for a Kentucky-based utility company. We are providing geotechnical engineering and materials testing/inspection services as part of a significant capacity upgrade to an existing ash storage area in order to extend the life of a coal fired generation plant with a net generating capacity of 563 megawatts. Additionally, Building & Earth personnel have been providing materials testing for two new 600′ stack units as part of a $1.3 billion modernization of another plant’s flue gas desulfurization scrubber system. The plant’s net summer capacity is 1,472 megawatts.

With demand for cleaner more efficient energy continuing to heat up, we plan to keep growing this business segment. Building & Earth looks forward to our role in helping clients meet the need, from the development of new power generation to maximizing existing generation systems.

Shooting for a Cause

February 15, 2014 Webmaster

At Building & Earth, community has several layers-the internal team, our professional relationships, our families and the cities where we live and work. Serving each of these communities is a privilege.

That’s why we are proud to partner with several others in the architectural/engineering/construction community to raise funding for Children’s Harbor, a not-for-profit organization dedicated to serving and strengthening children and their families. Imagined almost 30 years ago by the family who founded Russell Athletic, the Lake Martin, AL campus partners with more than 16 groups who serve the seriously ill and the disabled, providing camping and adventure services.

Last fall, the Building & Earth team participated in the 9th Annual Magic Moments Children’s Harbor Sporting Clay Shoot. The event has been a yearly favorite for us since it kicked off in 2004. All proceeds benefit Magic Moments and Children’s Harbor, and over the years, the event has raised more than $400,000 to support Children’s Harbor/Magic Moments in its mission. The teams we field enjoy the camaraderie, the weather and most importantly the knowledge that they are part of something much bigger than just another day of sport in the field.

This year’s event is set for September 24, and the folks at Magic Moments tell us it’s already filling up. Add your name to the participant list here. We’ll look forward to seeing you there!

Site Classification for Seismic Design

January 27, 2014 Webmaster

remi-1 We all know the old real estate adage: “Location, location, location.” In commercial and industrial construction, the saying goes beyond proximity or curb appeal. When it comes to design, one of the major ‘location’ considerations is seismic site classification. Several of the design parameters relative to site location can be determined by reviewing the Building Code Risk Coefficient Maps which are based on proximity to known seismic zones, however the specific subsurface conditions at the project site must also be determined. Even in areas relatively far away from known active seismic areas, the cost associated with seismic design can have a significant impact on the cost of the structural framework of the building. The biggest variable in the equation is the Site Class.

The Site Class is based on the average conditions present within 100 feet of the ground surface, and are designated as A-F, with hard rock, considered an ‘A,’ down to potentially collapsible soils, which get an ‘F.’ The Site Classification is based on shear wave velocity. For the A and B classification, it is preferable to measure the shear wave velocity on-site. The Building Code does allow the design condition to be estimated by a geotechnical engineer, engineering geologist or seismologist, with significant past knowledge of specific geologic formations and conditions (considering weathering and fracturing). Site Classes C, D and E can also be determined by seismic methods or typical soil drilling Standard Penetration Test (SPT-N) results. Site Class F is used for potentially collapsible soils, usually soft alluvial deposits.

Due to the cost of the exploration required to accurately determine the Site Class versus the relative additional cost to the structure, (savings on the order of 100x the cost of the analysis have been realized!) it is prudent to evaluate the upper 100 feet using soil drilling methods or seismic methods. Due to the relative quickness and ease and accuracy in which the seismic data can be obtained, the seismic method is typically more cost effective. Additionally, the building code limits SPT-N values to 100 if rock is encountered in the upper 100 feet, so when rock is present, it is not uncommon to improve the Site Class using seismic data relative to data from soil test borings. Pre-construction knowledge of the soil’s capabilities not only keeps everyone in compliance with International Building Code, it makes good business sense.

Building & Earth surveys are conducted using SeisOpt’s® patented Refraction Microtremor (ReMi®) technology.

This surface-performed geophysical survey evaluates surface waves, shear waves in particular. These dispersive waves are measured along a linear seismic array and evaluated relative to wave frequency and slowness. A seismograph, geophones placed in an array, and a seismic source are used to measure the propagating waves, all while data is recorded. This information is used to generate a 1-D subsurface profile based on the velocity with depth.

We’ve found that ReMi technology has some measurable advantages, including:

• Tests a much larger volume of the subsurface, in contrast to borehole measurements.
• Non-invasive and nondestructive, and uses only ambient noise as a seismic source.
• No permits are required for its use.
• No need to close a street or shut down work for the purpose of data acquisition.
• Usually takes less than two hours, from setup through breakdown.

The technology can also be used to determine liquefaction potential, soil compaction and subsurface geology.

Sinkholes: Causes, Identification and Remediation

September 10, 2013 Webmaster

Sinkhole-Collage-3

Sinkholes – The lurking underground menace. One day everything is fine and suddenly, with no warning, it’s not! OK, that may be a little sensational, but sinkholes sure do make the news when they occur. Just recently sinkholes in Florida caused the collapse of a large building and even a human death.

The areas in which sinkholes can occur are related to the geologic conditions, so the occurrence is not totally random. A knowledgeable consultant can assist in determining the relative risk of sinkhole development. As the title says, this article provides a short discussion of how to locate and treat sinkholes. Note the word ‘treat’ instead of ‘repair’. As with certain medical conditions, there is no cure for a site in sinkhole terrain-only treatment and application of suitable construction methods to reduce the risk of future sinkhole occurrences.

While the geologic conditions in which sinkholes can occur are known, the actual occurrence of a sinkhole is unpredictable. Subsurface conditions can stay in equilibrium and stable for many years, and suddenly change due to manmade changes such as pumping from wells or changes in surface runoff. Extreme weather variations such as heavy rainfall or drought can cause dropouts to suddenly occur at a site that was previously stable.

So, what is a sinkhole?
A geologist would say a sinkhole is a localized depression in the surface of the ground that was caused by the removal of underlying material. Naturally occurring sinkholes are mainly associated with limestone bedrock because limestone is susceptible to being dissolved by acidic groundwater. Other geologic formations conducive to sinkhole development include marble and dolomite.

Sinkhole Causes
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The dissolving (or solutioning) of carbonate bedrock occurs over thousands of years. As the limestone dissolves, soil erodes or ‘ravels’ into the open seams or caverns. The erosion progresses upward toward the surface until a surface collapse occurs. This is shown in the publication “Building on Sinkholes” by G. F. Sowers.

Consider the caves you may have visited. The cave networks are the underlying cause of surface sinkholes. When the roof of the cave collapses, or where cracks and fissures in the rock allow overlying soil to erode into the cave, the void can eventually reach the surface. The cave networks can be very extensive, such as Mammoth Cave in Kentucky where the network has over 50km of continuous subterranean passages.

When a large area underlain by such a cave network undergoes collapse and numerous sinkholes occur, the surface topography can change into a series of sinks and large closed depressions, the landscape is known karst topography. The term karst comes from the name of an area adjacent to the Adriatic Sea where natural sinkholes are numerous. The word ‘karst’ is used to describe areas where sinkholes, either natural or man-induced, occur.

The surface collapse can be slow or sudden, as seen in the Florida event. One of the largest sinkholes in Alabama occurred so suddenly that a local farmer felt his house shudder and then there was a sudden gust of wind within a few seconds. The sinkhole (referred to as the Golly hole) was later found to have a diameter of 300 feet.

Sinkholes may also be caused by man made factors as well. Broken storm water pipes are a common cause of soil erosion and subsequent surface dropouts. Underground mining activities have also been related to sinkholes.

Sinkhole Identification
Now that we’ve discussed the causes, how do you identify areas that are susceptible to sinkholes? Except for manmade features, geology is the major factor in sinkhole development. Most states and even some counties have publications that identify sinkhole prone areas. Aerial photographs (sometimes incorporating infrared cameras) can be used to locate existing dropouts or other karst features. sinkhole-4-300x225

After geological research of the site, a geotechnical investigation plan is developed and executed. The investigation may include:

Soil test borings to determine the consistency of the overburden soils. The soil test borings are usually drilled to auger refusal to check the variability of the bedrock surface. It is common to find soft soil conditions and an erratic rock surface in active sinkhole areas. It is important to determine the depth of the soft zone of soil above the rock relative to the thickness of undisturbed soil above.

Rock coring and/or air rotary drilling to assess the continuity of the rock. Clay filled seams, void spaces, or caverns in the rock increase the risk of future dropouts.

Geophysical investigations. Geophysical techniques may include electrical resistivity testing, ground penetrating radar, seismic soundings, or micro-gravity surveys. Electrical resistivity is usually used where clay overburden is present. Electrical resistivity imaging (ERI) is a technique used to map resistance to electrical flow in the ground at varying depths and lateral locations. Electrical current is introduced to the earth by two transmitting electrodes. The apparent resistivity of the subsurface is obtained by measuring the drop in potential between two receiving electrodes along the test alignment. The depth of investigation is proportional to the separations between transmitting and receiving electrodes. By varying this separation, as well as the separations between the pairs of transmitting the receiving electrodes, different depths and locations can be sampled to develop profiles of the subsurface apparent resistivity. These results can often distinguish more competent rock with higher resistivity values from water bearing, weathered or fractured rock having higher conductivity and lower resistivity values.

The results of the investigation are analyzed and the risk for future sinkhole development is assessed. Sites are typically assigned low, medium, or high risk depending on the findings of the investigation.

Sinkhole Remediation
The remediation or treatment options are based on the risk factors assigned to the site, the sensitivity and importance of the structure, and the risk tolerance of the client. There are several viable options to consider for sinkhole risk reduction. Some of the remediation options include:

Rock Supported Foundations. The use of rock supported foundations and a structural slab system is required to essentially avoid the potential complications related to future sinkhole development. Drilled piers, micropiles, or steel piles are considered for this application. However, there are limitations even for these systems and the risks should be evaluated carefully. This approach is not usually practical for most light to moderately loaded structures because of cost.

Grouting. Several grouting techniques are used for sinkhole remediation. Some of the methods include cap grouting, low mobility grouting, and dome filling. A typical grouting process is designed to fill the open voids in the soil and improve the consistency of the soil matrix. The grouting program is usually initiated on a 10 foot to 20 foot grid pattern. Depending on the grout take and pressures in the primary injection points, secondary or tertiary grout holes may be required.

Surface Stabilization Layer. The placement of a geogrid reinforcement layer at the subgrade level is sometimes used to reduce the risk of surface dropouts. The geogrid design is based on the ability of the geogrid to span over the certain size dropout. The major consideration with this method is the selection of the ‘design’ dropout opening. The geogrid manufacturer typically assists in the design services.

Excavation and Placement of Inverted Rock Filter. Repair of existing dropouts with excavation/rock replacement is probably the most common sinkhole treatment method. The excavation is extended to competent bedrock and durable rock is used to replace the removed soil. Large rock (rip-rap) is placed in the bottom of the excavation. Progressively smaller rock is used as the excavation is filled. The purpose is to allow flow of groundwater without causing soil erosion.

Conclusion
While sinkholes are and will continue to be a challenge for many project sites, a proper investigation program can provide the necessary insight to anticipate their presence and oftentimes mitigate their effect.

Old Man River Moving Faster

August 15, 2013 Webmaster

In 1935, the Tennessee Valley Authority built the Kentucky Lock and Dam. The site is located at the north end of the beautiful and historic Land Between the Lakes National Recreation Area, just off the Tennessee River in Grand Rivers, KY. Today, it’s operated by the United States Army Corps of Engineers‘ Nashville District and handles 50 million tons of barged cargo every year. To move more freight up and down the river, an initiative to build an Upstream Lock Monolith Addition was launched in 2009.

Building & Earth is providing construction quality control services on the new 110 ft x 1200 ft lock, which will increase capacity to handle larger barges and heavier traffic. The project required the excavation of 500,000 cubic yards of overburden, pre-splitting almost 40,000 square feet of rock, excavation of 100,000 yards of rock, and placement of 130,000 cubic yards of concrete, all with very tight tolerances. All QC testing was conducted with onsite USACE validated laboratory facilities.

The new lock is adjacent to the existing lock channel which remained active during the construction process, increasing the difficulty of the construction. A series of challenges had to be overcome. The site is situated in a cavitated limestone geologic setting, and the project required pressure grouting of voids and cavities in the rocks before concrete placement could even begin.We worked in cold weather, with the wind from the body of water making conditions even worse. The extremely deep excavation required us to be innovative to transport equipment and samples from the base of the excavation to our laboratory facilities.

In the end, the Upstream Lock Monolith addition will allow for larger barge access and faster passage, reducing wait time for vessels. Building & Earth was proud to be involved with the construction of this $734.5 million project.

Setting the Pace for United Way

July 25, 2013 Webmaster

The United Way, one of the nation’s largest and most well-respected charitable organizations, is a force within communities, identifying, funding and resolving a wide range of pressing issues. Each year, our local organization’s annual funding campaign kicks off in September.

In June, the United Way selects companies with a strong tradition of support to conduct their annual giving campaigns a little early, ‘setting the pace’ for the fall giving drive. Building & Earth was pleased to be selected for this Pacesetter Campaign.

The kickoff event was June 13th at the Birmingham Barons vs. Jackson General’s game at Regions Field. Click here to read more about our involvement with the structural steel, masonry and concrete at this downtown baseball park.

Our corporate office in Birmingham announced the Building & Earth campaign with a lunch and presentation by Karen Gandy and Ladye Franklin. Karen is a loaned executive for United Way of Central Alabama, and Ladye represented ‘Success by 6,‘ a preparedness program for pre-schoolers that the United Way sponsors. Branch offices also had representatives speak to employees and encourage generosity.

We are pleased to announce that when the campaign ended on July 19, our company raised more than $32,000, a nine percent increase from 2012.

Our involvement will continue with Controller Filmore Woodbery, who will be a Visiting Allocation Team member for the United Way. This fall, Fil will be part of a small group who visits with UW receiving agencies. They will be gathering information, then consulting and assisting the United Way in determining an appropriate allocation of funds.

Building & Earth couldn’t be more pleased with our team’s willingness to give both their resources and their time. We are looking forward setting the pace again next summer.

More for Moore

May 24, 2013 Webmaster

Last month, our nation was struck with tragedy as the people of Oklahoma endured one of the most destructive tornados on record. The news was particularly hard for our team, as many of our Tulsa location employees witnessed the weather first hand.

Our own Tim Ellerbe, a technician based in Tulsa, has been volunteering his time outside of work to help with the recovery efforts in Moore, OK. Here is an excerpt from his heartfelt request for donations:

“As most people around the world now know, Moore, OK has been completely destroyed by an EF-5 tornado. After much speculation, it has been confirmed that the tornado caused 24 casualties in its path of destruction. The tornado was 1.3 miles wide, with winds in excess of 210 miles per hour and left a 17 mile trail of absolute devastation. What has been forgotten is that there was also a pair of F-4 tornados the day prior in Carney and Bethel Acres, OK, causing one casualty and destroying those in the wake.
The last total I heard on the news was 2,400 homes lost or damaged, 10,000 people immediately affected. In following with the compassion I have seen shown, I ask that you help in any way that you can…”

Our Birmingham/Corporate office was glad to aid Tim by collecting monetary donations to help in the recovery effort. Building & Earth Sciences generously matched employee giving. We are proud to have a leader like Tim in our midst, and our hearts are with those still recovering from the tornado’s aftermath.

On Our Radar: Birmingham Bond Work

May 23, 2013 Webmaster

Birmingham

Last fall, voters overwhelmingly approved a bill allowing the city to issue $150 million of bonds for capital projects and improvements in Birmingham. Here’s what passed:

– $6.3 million for landfill improvements and expansion
– $20 million for public park and recreational facilities
– $48.7 million for street and sidewalk improvements
– $19 million for industrial park and economic development
– $45 million for public building facilities and equipment
– $11 million for storm sewers

The first phase of work will be $72 million, with the remaining funding on hold for future use.

We are pleased to be a part of a significant expansion at the New Georgia Landfill, a 15.5 acre Municipal Solid Waste (MSW) landfill unit just north of downtown. Work will include excavation, subgrade preparation, berm construction and installation of liners, collection systems and drainage structure. A protective layer and ditch system will also be put in place. Our Scope of work includes management of the project Quality Assurance/Quality Control (QA/QC) program for the project as well as all associated construction materials testing and inspections.

After a few months of debate, the Birmingham City Council still hasn’t given its final stamp of approval to all the capital projects, but the implications remain the same: There’s a lot of potential work ahead for local architectural, engineering and construction sectors.

In our view, the bond money will greatly influence the next few years of development in our industry, possibly marking the end of the Great Recession for Birmingham municipal construction.

From Railroad Park to Regions Field…

May 17, 2013 Webmaster

While every project we touch is special in its own way, projects that help our hometowns hit extra close to home. Notable examples include ONEOK Field, home of the Tulsa Drillers minor league baseball team, and Auburn Arena, where the Auburn University basketball team plays.

When redevelopment began in Birmingham’s city center, we jumped at the chance to be a part of it. Just a few miles down the road from our corporate office, Railroad Park and the adjacent Regions Field were a large influence on what has become a downtown renaissance. Only three years old, the Park is used for frisbee games and symphony concerts alike, while Regions Field recently opened as home to our minor league baseball team.

Our work at Railroad Park started with the initial project planning in 2007. We provided environmental and geotechnical assessments of the site to aid in park design. This included evaluation of soil and groundwater, site earthwork, structure foundations and groundwater depth. As the park progressed, we provided geotechnical evaluation for elevated walkways, the planned pond and additional structures. During construction, we monitored the earthwork, tested soil, sampled and tested concrete and grout, and inspected the structural steel.

At Regions Field, our responsibilities included special inspection of structural steel and sampling and testing of above-grade masonry and concrete.

The structural steel inspection was a challenge due to the fast track schedule required for the steel erection. We had as many as four Certified Welding Inspectors on site at any given time. Our steel inspectors performed visual inspection and non-destructive weld inspection using Ultrasonic Testing methods. Construction inspections continued right up through opening day and beyond.

We were proud to be part of both projects, which are considered integral to downtown redevelopment and revitalization in Birmingham. They are a rallying point for our hometown and for the Building & Earth team.

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Report recommends $100,000 fix for Chief Ladiga Trail sinkholes