White River Hydroelectric – Marine Blasting

PROJECT DETAILS

The White River Hydroelectric Power project is located near Batesville, Arkansas. Batesville is the second oldest municipality in the state of Arkansas, after Georgetown. It was named for James Woodson Bates who settled in the town and was the first territorial delegate from Arkansas to the Congress of the United States. Batesville has also gone by the names of Napoleon and Polk Bayou.

In early days, Batesville was an important port on the White River and served as an entry point to the interior of northern Arkansas. Batesville played a large role in the settling of the Ozark Mountains region and served as the central land office for northern Arkansas

The first known settlement of the Batesville area was in 1810 near the mouth of Polk Bayou, and by 1819 the town had a ferry across the White River and about a dozen houses. The town was partially laid out in early 1821, and on March 3, 1822 a bill of assurance was recorded and executed and the town’s plat was laid out. Batesville became the county seat in 1821. In January 1822, Judge Richard Searcy opened the town’s first state circuit court. The town’s first post office was established in 1822, and in 1830 became the home of a county court. On 25 September 1836, shortly after Arkansas was granted its statehood, Governor Conway incorporated Batesville Academy, the state’s first academy. In the past, the area in and around the city had extensive quarries of manganese ore, phosphate rock, sandstone, limestone, and marble. Currently Arkansas Lime owns and operates a lime kiln nearby and there are a few limestone quarries operating in the area.

A major event occurring around the turn of the century was the beginning of construction of three locks and dams to make White River navigable above Batesville. According to the U. S. Army Corps of Engineers, the River and Harbors Act of March 1899, authorized ten fixed dams with concrete locks between Batesville and Buffalo Shoals. Three of these locks and dams were completed; No. 1 at Batesville and Nos. 2 and 3 up the river from the town. Lock and dam No. 1 was placed into operation October 16, 1903, and the other two were not far behind, but while construction was going on, the railroad began building the White River Division which paralleled the river to Cotter. The railroad with through connections offered better service and the lock and dam project was dropped after No. 3 was finished. However, the government maintained the three which were built until 1951.

After the locks and dams were taken out of service they were sold by the U. S. Army Corps of Engineers for private ownership. This is the only time in the history of the United States that this had ever been done. Eventually Independence County acquired ownership of all three of them and plans were made to convert the old locks into hydro-electric generating stations.

Architects went to work on designing the generators and in April 2004 Mobley Contractors, Inc. was awarded the contract and began construction. Work started on site #3 located near Marcella, Arkansas. The lock structure was too deteriorated at that location so a new site was excavated to the side of the White River. When the powerhouse was constructed channels were excavated up and downstream of the structure to allow water in and out of the generator. The sides of the channel were line drilled on one foot centers to limit rock breakage beyond the excavation limits and up to 20 feet of rock was precision drilled and blasted out for construction of the powerhouse and the water channels.

The generator at Site #2, near Desha, Arkansas was constructed within the lock itself. The lock underwent significant modification and reinforcement construction in order to contain the new powerhouse. Rock excavation in bottom of the lock was necessary in order to achieve grade depth for the powerhouse. There was also some underwater rock excavation in the upstream channel in order to allow water in and out of the generator.

The concrete upstream gate sill, water intake manifold and front entry sill were part of the original lock construction and had to be removed from within the lock without any damage to the existing structure to remain. This phase of the project was achieved with precision controlled drilling and blasting techniques designed to fragment the concrete to be removed while leaving the remainder of the lock undamaged.

The generator at site #1, located in Batesville, Arkansas was the most challenging by far. This lock required up to twenty two feet of rock excavation below the bottom of the lock walls inside the structure. This work was complicated by a number of factors. The sheer volume of rock that was required to be removed which was in direct contact with the footings of the existing lock to remain, the close proximity of an open restaurant overlooking the entire project within sixty feet of the closest rock excavation, a thirty inch above ground wastewater sewer main less than twenty feet from the closest rock excavation and only ten feet from the pristine White River, boat traffic and interested pedestrians present at all times.

This lock also had the concrete sills and the water intake manifolds which obstructed the water flow into the powerhouse. These concrete structures had to be removed but with an addition level of difficulty. The logistics of this location required that these be removed with the lock and powerhouse already watered up. The precision concrete removal had to be done underwater. Once the required concrete demolition was finished, an additional two to eight feet of rock had to be excavated below the bottom of the concrete sills on a 6 to 1 slope to allow the water unimpeded and down slope flow into the powerhouse water intake.

The upstream end had some minor underwater rock excavation which had to be performed in a maximum of thirty seven feet of water. The downstream end of the lock structure had to be excavated from twenty two feet below the bottom of the existing lock walls on a 6 to 1 slope going downriver and fanning out into the main river channel on a 45 degree angle. All of this drilling and blasting was performed underwater.

This challenging three year project was successfully finished on time and with no lost time accidents. The hydro-electric generators are now in full operation. Dykon Blasting would like to give grateful acknowledgment to Mobley Contractors, Inc for their trust and support during this difficult project. Their professionalism and attention to safety, detail and work coordination was unequaled in the industry. We hope to work with them on projects in the future.