As industrial facilities age, they increasingly require maintenance and upgrades to continue normal function. Some of this remedial work may result from deterioration of structures and equipment with time, while other reasons may include mandated regulatory upgrades and the need for increased capacity. Upgrading and remediation of physical structures typically requires expertise in civil, geotechnical, hydraulic and structural engineering, which are primary components of D'Appolonia’s engineering practice. We are frequently retained to assess conditions associated with electrical power generation plant site conditions and infrastructure. The scope of work has included evaluation of displacements at heavy equipment foundations, evaluation of damage to piping and foundations due to subsurface consolidation or movement, and design of repair/rehabilitation measures. We have designed repairs/modifications to heavy equipment foundations, piping and conveyor systems, spillway concrete and gate systems, and have designed temporary retaining walls and other measures related to new site construction.

Twin 11-foot-diameter cooling water intake pipes designed by D'Appolonia to replace an intake canal that was functioning poorly due to Asian clam infestation resulting from low-velocity flow.

Descriptions of D'Appolonia projects related to power plant infrastructure rehabilitation are provided in the following:


Rehabilitation of Fossil-Fuel Power Plant Infrastructure

D’Appolonia conducted a geotechnical/structural evaluation, prepared remedial designs, and provided construction management to address problem operating conditions of components at the Decker Creek Power Station in Austin, Texas. Unit One of the 920-MW power plant had experienced structural problems due to movement of underlying expansive foundation soils. The most significant movements included: tilt of the mat foundation supporting the Turbine-Generator (T-G) pedestal; distortion of high-energy piping systems in the plant; cracking and offsets in the concrete spillway for the dam impounding plant cooling water; and cracking and heaving of the cooling water intake canal’s concrete floor.

Emergency Foundation Support and Long-Term Stabilization

Following the failure of some major facility foundations at an electric power plant due to the collapse of a large-diameter subsurface pipe, D’Appolonia was retained to develop and manage the implementation of emergency remedial measures to provide temporary support and in the long-term to restore the function of affected structures.

Engineering for Low-Head Hydroelectric Power Installations

D'Appolonia was retained to assess the site development requirements for low-head hydropower installations at two lock and dam sites on the Allegheny River near Pittsburgh, PA. The work included flood routing studies to evaluate the effects of temporary river restriction resulting from temporary cofferdams and permanent facility construction.

Excavation Support Systems for Saluda Dam Rehabilitation

D'Appolonia was retained by a construction contractor to design temporary retaining structures related to construction activities at Saluda Dam. Work performed by D'Appolonia included (1) design of two anchored tie-back wall sections totaling nearly 500 feet in length, (2) anchoring of an existing concrete retaining wall located behind the hydroelectric plant, (3) support for two anchor blocks supporting the circulating water lines for the hydroelectric plant, (4) design of two temporary cut-off walls, and (5) design of two temporary soil nail walls.

Rehabilitation of Fossil Fuel Power Plant Hydraulic Structures

D'Appolonia was retained to develop designs for rehabilitation of hydraulic facilities at the Decker Creek Power Station. The work included replacement of an intake structure that was infested with clams, repair of spillway tainter gates, repair of spillway concrete, design of shore protection for the cooling reservoir and other remedial tasks.

FERC Part 12 Dam Safety Inspections and Remedial Studies

For Hawks Nest Dam (part of a hydroelectric generating facility), D'Appolonia has performed FERC Part 12 dam inspections and provided engineering services related to remediation of scour at the toe of the spillway, repair of spalling of the face of the spillway, and resolution of other maintenance issues associated with the dam and power generation equipment.