Brushy Creek Bridge Footing Pour

This past week Teichert Construction completed their first major concrete operation, Brushy Creek Bridge footing pour. A concrete pumping truck set up between the two bridge abutment footings while concrete trucks lined up to supply the materials. County Inspection staff monitored the pour itself while County Materials Testing laboratory staff verified the material quality and obtained samples for further quality assurance sampling.

Concrete being pumped into the Abutment 1 footing form.

Concrete at the Abutment 1 footing, lowest step.

County Materials Testing Laboratory Staff obtaining concrete samples onsite for quality assurance compressive strength testing.

Bridge Footings and Shotcrete Test Panels

This past week Teichert Construction began forming the bridge footings and installing the rebar in anticipation for a concrete pour next week. The recently driven piles are anchored to the footing via rebar which also extend up into the bridge abutments. Pre production soil nail wall work continued this pass week with additional verification nail testing and pre construction shotcrete test panels. Upon installation of production soil nails, shotcrete will be used to in conjunction with wire mesh and reinforcing steel to form the retaining wall face itself. This will maintain the wall face integrity while the soil nails stabilize the hillside behind the retaining wall. Test panels of shotcrete are built by Teichert Construction prior to actual wall construction for Construction Inspection to verify the quality of shotcrete workmanship and confirm its strength properties prior to production.

Concrete forms and rebar at the Abutment 1 stepped footing.

Concrete forms and rebar at the Abutment 2 footing.

Construction of a shotcrete test panel (with reinforcing steel).

Pre production shotcrete at a verification nail face.

Pile Driving and Verification Nails

This past week Teichert Construction completed pile driving installation for the abutment foundation at Brushy Creek. Forty-five to 60 ft long steel H-beams were driven into the soil beneath the abutment footing to provide a secure and stable foundation for the bridge widening. The piles are struck by a pile hammer with sufficient energy to drive the steel through the surrounding creek alluvium and deep into bedrock. Observation of the pile driving operations by County Inspection confirmed the existence of a hard sandstone layer (at shallow depths at the northern abutment) within the foundation's geological layer. This rock stratification provides a good substrate for the piles to secure the bridge footing and abutment. Other construction operations last week included the completion of exploratory drilling for the soil nail retaining walls at the northern and southern project limits. Verification nails were installed to confirm County Design's soil assumptions for the retaining walls. Soil nail retaining wall systems will be constructed as part of the Vasco Rd Safety Improvements project. "Soil nails" of various lengths are installed in bored holes along the hillside. The nails are then grouted in place with high strength concrete. As a complete system, the friction created between the grouted nails and existing soils secure the hillside and prevent slides from occurring. The current verification nail process consists of installing test nails at various locations to identify current soil conditions and quantifying the load the designed soil nails can sustain. Upon completion of this verification process, the "production" nails can be re-designed (shortened) to reduce costs if the existing soil conditions are better than originally anticipated.

Teichert Construction pile driving rig setting up at the southern abutment.

Pile driving at the southern abutment.

Piles driven (at the northern abutment) into the existing sandstone layer, which encountered competent bedrock at shallower depths than expected.

Teichert Construction drill rig beginning to bore for a verification soil nail.

Inclinometers and Bridge Foundation Work Begins

This week Teichert Construction started to access the hillside north of Brushy Creek bridge to prepare for installation of 2 retaining wall structures. Part of this preparation work is exploratory drilling and inclinometer installation. Exploratory drilling in the hillside is necessary for County engineers to confirm the existing hillside soil conditions and make any necessary modifications to the retaining wall design prior to actual installation. Inclinometers are plastic casings (90 ft in depth) installed on the hillside that are located behind the retaining wall location that measure any hillside movement. Measuring any "hillside" creep is necessary as part of the overall installation process to ensure that retaining wall construction isn't affecting slope stability and as well as providing long term maintenance monitoring. Progress continues with the Brushy Creek bridge widening effort as Teichert Construction crews excavated for foundation footings at the south abutment. This operation will be followed with pile driving, anticipated to begin next week (6/28/10).

Looking north at an inclinometer location. Note, the portion of the hillside, leftside in the picture (down slope) will be excavated for the retaining wall itself.

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Inclinometer casing.

Teichert Construction crew excavating the footing for the southern abutment.

EXPECT DELAYS: 6/24

Teichert Construction will be implementing 1 lane traffic control along Vasco Rd (at Brushy Creek bridge) on Thursday, 6/24/10, from 9 am to 3 pm. Commuters should expect delays while County biologists work on the bridge to re attach netting to prevent birds from nesting on the bridge structure itself. Surprisingly, the concrete angle points on bridges are prime habitat for birds to form "mud" nests. Birds that form new homes on the bridge may delay the project so County biologists monitor and implement measures to prevent birds from establishing nests. On Brushy Creek bridge, netting is installed under the bridge at the abutments and along the edge of deck. Due to the high winds, netting must be constantly maintained and reattached to prevent it from blowing onto the roadway itself or falling into the creek, which is sensitive habitat.

Netting installed under Brushy Creek bridge at the angle point created by the existing abutment and superstructure.

Brushy Creek Bridge Demolition

Teichert Construction crews completed the majority of the Brushy Creek Bridge demolition this week. The demolition operations were limited to the existing barrier rail on the bridge along northbound Brushy Creek Bridge. A minimal portion of the existing deck was removed so the final concrete pour (closure pour) will transition the existing bridge deck to the new bridge grades. Portions of the exposed rebar on the existing bridge will connect to rebar/concrete in portions of the new bridge widening.

View of the existing bridge with the northbound barrier rail removed and exposed rebar.

County Construction Inspection reviews the operation to confirm the limits of demolition and ensure that the existing structure remains undamaged.

Getting Ready for Bridge Demolition

One of the Stage 1 construction improvements is the Brushy Creek Bridge widening. Dewatering of Brushy Creek was just the first step in preparing the area for the actual bridge construction. The next step is preparing access to the future bridge foundations, establishing a work area in the dewatered creek, and demolishing the existing bridge barrier rail. Teichert Construction began these initial operations earlier this week by adding metal plates over the creek to protect the bypass pipe from construction equipment and demolition debris. A breaker on the back of a backhoe will do most of the demolition work later this week.

A backhoe with a breaker stages on the work side of the k-rail.

Since the k-rail will prevent vehicles from entering the work area where the existing edge of bridge deck (barrier rail) will be demolished, it must be doweled into the existing bridge deck to prevent movement from collisions with vehicles that may have gone astray.

Looking down from the barrier rail (to be demolished), Teichert has established a work area for future falsework and pile driving operatons while protecting the dewatering pipe from construction equipment and demolition debris.

Stage 1 Traffic Handling Plan Complete

Teichert Construction completed implementation of the Stage 1 Traffic Handling Plan this week. This plan consists of removing existing rumble strips, traffic striping, and installing temporary concrete barriers (k-rail) along the roadway to establish a safe work zone away from vehicle traffic. A significant portion of this work took place at the northern project limit to accommodate the future Brushy Creek Bridge widening work and Soil Nail wall operations.

Looking Northbound along Vasco Rd at the northern project area.


The established work area behind the k-rail for the Brushy Creek Bridge widening work.

Water Control of Brushy Creek

Teichert Construction began implementing their water control plan in the Brushy Creek Bridge widening area. Water control or dewatering of Brushy Creek consists of establishing a "dry" work zone in the creek in advance of actual bridge widening construction. The water control plan (also referred to as dewatering plan) consists of installing a silt filter barrier at the downstream work limits and upstream cofferdams. The existing creek flow is diverted through a plastic pipe so clean upstream water bypasses the work area and is discharged downstream of the work area. The silt filter barrier at the downstream end ensures that any work zone runoff is treated prior to flowing downstream of the work area. Initial water quality sampling that compares upstream and downstream water quality during this dewatering operation indicates that none of the operations have adversely impacted the creek water quality. County Construction Inspection provide biological monitoring to identify and manage wildlife encountered during creek work since California red-legged frogs have been sighted this last week.

While creating access to the creek, an excavator makes repairs to the ESA-silt Fence. Maintaining the fence along the project limits is vital in preventing animals from entering the work zone and being harmed as well as treating storm water runoff that may enter the creek.


Looking downstream (from the upstream cofferdam area), Teichert Construction begins to secure the dewatering bypass pipe with existing river rock.

EXPECT DELAYS: 6/7 to 6/9

Teichert Construction will be doing roadwork along Vasco Rd on Monday, 6/7, to Wednesday, 6/9. Advance notice was given to commuters this past Friday, 6/4, by portable changeable message boards that are along the Vasco Rd. The anticipated construction work hours in the roadways are from 8:30 am to 3:00 pm. The purpose of this work (anticipated to take 3 days) is to continue the installation the Stage 1 traffic control. Teichert Construction removed the existing rumble strips and striping this past Friday (6/7). Construction operations in the road this upcoming week will be focused on installing the k rail (temporary concrete barriers) for Stage 1 traffic control. Upon completion this stage's traffic control, the majority of construction activity can take place behind the temporary k-rail, 2 lanes Vasco Rd traffic will be routed through the work zone, and construction impacts to Vasco Rd commuters will be minimized.