HydroVac for Congested Area Dilemmas

One of the toughest challenges that contractors face while performing pipeline maintenance, repairs and/or expansions in a plant or refinery is excavating in areas that are inaccessible to traditional excavation equipment. Confronted with such a dilemma, one of the largest gas plants in the world recommended that a foundation contractor consult Hydro Spy, LLC.

Hydro Spy was brought in for two reasons. First,  more than 600 ft of trenching was needed for the installation of ground wire. In addition to concerns about the presence of underground utilities, energized equipment was strictly prohibited in this specific area of the plant. The solution Hydro Spy provided was the utilization of industrial vacuum hoses to perform the excavations as for away as 300 ft from the hydro excavation unit.

The second challenge involved the excavation of multiple pier shafts in areas that one could hardly walk upright in because of the labyrinth of overhead piping infrastructure. The areas provide no access for mechanical equipment, and hand-digging was not an option because of the proposed depth of the shafts. Each shaft was to 36 inches in diameter and 12 ft deep. The solution Hydro Spy provided in this scenario was use of flexible industrial hose to vacuum excavate the soil from the diameter of the hole as it was surgically broken up by controlled water pressure.

According to the plant managers, in addition to the obvious safety advantages, the hydrovac procedure for the pier shafts actually proved to be more efficient than digging with an augur in certain areas of the plant, regardless of accessibility. Cave-ins had plagued drying drilling efforts, and often multiple types of heavy equipment were needed to get one hole done. With our hydro excavation application, Hydro Spy cut a hole straight down, and the hole was somehow able to stay intact long enough for the foundation contractor to set rebar and pour concrete without ever using a casing or sleeve to keep the hole open.

Craft Notes: In dry ground conditions, the injection of water can provide temporary cohesiveness. However, communication, experience and timing, in that order, are critical for a successful outcome. After assessing the situation, the hydrovac contractor must communicate with the foundation contractor and outline a plan of action that qualifies the entire effort as a joint venture. In this scenario, the foundation contractor had to have a sonotube casing near the hole, ready for cutting and installation, regardless of achieved depth, upon request. The rebar and means of installation had to be signal-ready. Keep in mind that, despite the use of a sonotube casing, water-logged ground conditions can limit the amount of time the casing will hold back the pressure of collapsing walls. Inexperience, lack of communication or a break-down in executional logistics can frustrate any effort to excavate in this manner. The X factor is working together. Team work!