Burdekin Falls Dam, Queensland, Australia

Constructability reviews to install post-tensioned, 91-strand vertical anchors on 1650 ft. wide Ogee crest spillway to address stability concerns. Possible crest raising & abutment buttressing. Spill capacity 2.3 million cfs or 64,600 m3/sec 

Constructability planning for removal of 5 meters from the 1,000 ft. wide RCC ogee crest of the Paradise Dam Spillway.  Member of a design-build team working with General Contractor: CPB Contractors of Fortitude Valley, QLD 

Removal of existing concrete crest parapet wall. Removal of existing concrete in back wall, shaft lining, and tunnel lining. Furnishing & placing cast-in-place concrete to construct new south spillway overlay walls and weir wall, new parapet wall, and to make repairs to existing back wall, shaft lining and tunnel lining. Excavate existing dam embankment, constructing two-stage filter of sand filter and gravel drain materials in area of existing dam embankment and north spillway wall. Furnish & install collector drains in back wall. Remove existing left drum gate and abandoned drum gate control piping, control valves, and appurtenant parts for each gate, rehabilitate right drum gate including removing and replacing seals and drums. Sand-blast, remove, and dispose 8,000 sq.ft. lead-based paint. Repair & modify gate, coat interior and exterior of gate and coat inlet side of gate.  

Remove & replace the entire left (vertical) concrete spillway wall from Sta. 17+27 to Sta. 19+22; approximately 200 CY’s. Repair approximately 277 CY’s of damaged concrete in spillway floor & walls; furnish & install a PVC liner-drain system behind the left spillway wall; furnish & install wall drainage pipe and site corrugated metal pipe.  High scale & rock bolt the rock face above the spillway chute.  *As work progressed, the condition of the concrete was worse than anticipated. ARRA funds were used to expand the scope of the original contract. 

Demo & remove 70 CY’s of existing cast-in-place concrete ogee crest in spillway. Replace it with new cast-in-place concrete ogee crest that extends spillway 4 ft. higher and cantilevers over reservoir. Modify upper gate trash rack on existing intake tower. Required extra measures to maintain the safety of the crew and to keep debris and materials from entering the water. DeNeef chemical grouting of upstream cracks in dam to stop persistent leak. 

Construction of a 1,000 c.y. reinforced concrete floor overlay within the 660’ long spillway chute, installation of anchors & dowels in the existing chute floor slabs & walls, removal of 42 c.y. concrete at upstream & downstream ends of overlay, dewatering and unwatering spillway chute & stilling basin to allow placement of concrete overlay, construct & remove downstream cofferdam, and cleaning & removal of debris from stilling basin. Backfill grouted voids under spillway intake slab.

Surface tolerances on the concrete overlay were critical to avoid future cavitation problems during high spillway releases. This was achieved with a custom designed and built pan screed system similar to what is used on steep canal or dam face paving. 

Saw cut & remove approximately 19 cy of existing concrete within the spillway, repair & replace the existing reinforcement, and place new concrete in the areas being repaired using replacement concrete. Due to the slope of the spillway, much of the work was performed under the USBR’s rope supported work guidelines 

Saw cutting & removal of 35 cy of existing concrete within the spillway, repair & replace existing reinforcement, place new concrete in areas being repaired using replacement concrete. Due to the slope of the spillway, much of the work was performed under the USBR’s rope-supported work guidelines 

Saw cut & removed approximately 76 CY of existing concrete within the spillway, repaired or replaced existing reinforcement, dewatered spillway’s stilling basin, sandblasted & coat frames on the spillway’s flap gates, removed & replace leaves on the spillway’s flap gates.

Design and install a shaft access system (150 ft. construction elevator) for a Morning Glory spillway rehabilitation project. The work consisted of the demolition of concrete from the interior of the 15’ diameter vertical spillway shaft. Furnish, install, and weld in place approximately 129’ of 1” thick x 15’ diameter type 304 stainless steel liner. Pressure grout (833 bags) the annular space between the liner and the shaft, and repair isolated areas of deteriorated concrete in the tunnel below the level of the stainless steel liner. Chemically grout shaft walls to stop water infiltration with DeNeef Active Flex LV. 

Demolition and replacement of 325 cubic yards of deteriorated concrete in a 30’ diameter spillway tunnel. Drilling & grouting dowel bars for rebar reinforcement. The tunnel was inclined 50 degrees creating extremely difficult access. The project required the construction and use of a highline cableway to muck material across the river. Epoxy painting of numerous concrete surfaces.

 Work involves saw cutting, removing and replacing approximately 14.3 cubic yards of concrete at intake structures on face of 250’ high concrete dam; preparing, caulking, and sealing approximately 380 square yards of new and existing concrete; modifying existing crane rails; and furnishing and placing 135 tons of asphalt 

Sawcutting, demolishing, and removing 30 cubic yards of existing reinforced concrete. Made repairs to existing reinforced concrete chute, including epoxy bonded concrete, concrete caulking and concrete sealing compounds: construction of subsurface drains at Roza Wasteway No. 2. Backfill grouted voids (0 to 10”) under spillway slab, using 402 bags of cement.

The removal of calcium deposits inside the spillway tunnel by grinding; removal of concrete and saw cutting around cavitated areas to a depth of 1-1/2"; drilled holes in existing concrete lining and grouted dowel bars for reinforcement bar anchoring. Furnished and placed approximately 40 c.y. of reinforced replacement concrete for concrete repair in damaged areas.

Added access bridge and 25 ft of formed concrete to top of existing 325 ft high gravity arch dam (built in 1909). Constructed a gated spillway which included two 20' x 28.5' top-seal, hydraulically operated redial gates and a control building of structural concrete. Concrete-lined the invert and walls for 40' x 40' x 600' discharge tunnel, (approximately 10,000 CY concrete). This project required drilling, blasting, and excavation of 48,000 CY of shot granite, which Moltz processed for riprap. Much of work was performed using platform suspended from crane. Installed epoxy rock-bolts. Drilled shot and removed rock cofferdam, mostly underwater that was in close proximity to the intake gates.

Very controlled blasting techniques were required due to proximity to dam. Maximum peak particle velocity = 2" / second was adhered to the 40 ft x 40 ft spillway face was bench-blasted using ECM 250 air track drill and gel dynamites. Much of concrete for intake control structure was poured during the winter months, requiring heating of concrete mix water as well as maintaining heated curing conditions.

Work involved saw cutting, removing and replacing approximately 30 cubic yards of concrete, preparing and sealing approximately 11,325 square feet of new and existing concrete surfaces. Caulk existing joints & transformer deck.

 Constructability review & estimate for demo & replacement of 110’ wide  x 1,500’ long chute spillway damaged by Hurricane Agnes.

Demolishing the entire existing spillway; installing a new spillway underdrain system; constructing a new concrete spillway including a spillway chute, drain, and stilling basin. Erosion and sediment controls; clearing and grubbing; stripping and stockpiling topsoil; installing a new filter blanket on the downstream slope of the embankment; placing fill on top of the filter blanket on the downstream slope of the embankment; reseeding. Remote location at 10,200 ft elevation. Worksite was only accessible from May 1 to October each year.