Reduce Construction Material Sent to Landfills

After reaching a collaborative agreement with the South Coast Air Quality Management District (SCAQMD), Kiewit Infrastructure West Company (Kiewit), prime contractor for the I-405 Sepulveda Pass Improvements Project, has received approval to operate material-crushing sites within the project boundaries.

The crushed material, termed “aggregate,” will form the base of the new roadway laid by the I-405 project. This will eliminate traffic from trucks hauling that material offsite and save approximately 300,000 tons of demolition material from reaching local landfills. That equals the weight of more than 220,000 Honda Civics.

“You’re cutting down on greenhouse gases by not having to put additional trucks on the road,” according to Allen Gershenson, Kiewit’s environmental officer for the project. “Material never leaves the project boundaries.”

According to Gershenson, meetings between the contractor and the air quality district started in August 2009. Looking to forge a more cooperative relationship, Kiewit met with both the permitting and enforcement arms of SCAQMD simultaneously, hoping to bring transparency to this years-long working relationship.

“Our goal and objective was to get concurrence from both ends,” Gershenson explains. “We wanted to build up a relationship with the regulators. I would rather be transparent and have SCAQMD involved from the beginning. It makes me feel good that I can call these people and ask them a question.”

Kiewit, which had never before reached an agreement of this scale with SCAQMD, also committed to making access to the crushing sites easier for inspectors. In fact, SCAQMD staff has already toured each crusher site.

“We brought in 10 SCAQMD inspectors and put them through safety indoctrination,” Gershenson recalls. “We opened the door for them. If they come onsite, they don’t have to call ahead or call our safety officers.”

“If we’re doing something wrong, this agreement isn’t going to stop SCAQMD from sending us a notice of violation; but at least we’re starting this operation knowing what marks we have to hit,” Gershenson believes.

Even with SCAQMD permission to operate the crushers, Kiewit must follow its dust abatement plan and meet noise requirements as it crushes asphalt and concrete. Steel will be sent to recycling centers. (No asbestos was discovered in the Sunset Bridge.)

Tentative operating hours for the crushers are 7:00am to 3:30pm, Monday through Friday. If crushing needs to be accelerated, weekend work may be needed, as would night work. Noise must be kept below 86 decibels (average) between the hours of 9pm and 7am. If noise exceeds the 86 decibels threshold, work will be conducted during daytime hours only.

The permit granted by SCAQMD limits the daily and annual quantity of material that can be crushed, based on the emissions produced by the crusher. Therefore, the quantity of crushed material is monitored daily.

Each crusher will be powered by an onsite diesel generator, according to Kyle Nakamura, Kiewit’s Segment 3 manager. The generator will be fueled from a double-walled tank mounted on a concrete slab at each crusher site.

Several crushers will work within Segments 2 and 3. After consulting with SCAQMD, Kiewit eliminated a crusher it had hoped to place in Segment 1.

While SCAQMD has approved seven crusher sites, only five crushers can be used at one time. Three will be recycling crushers and two will be aggregate crushers. (The recycling crushers will process material taken from demolition. The aggregate crusher takes rock from excavated hillsides adjoining the project.)

To control dust from leaving the crusher site, Gershenson describes several control measures: “Some of the crushers have misters and bag houses [to trap dust]. Smaller crushers have water trucks to control dust. Dump trucks will have tarps covering their beds. The covers roll back in place when dumping ends. Devices will also be used to reduce dirt being deposited on roads outside each site.”

Similar devices within the project boundaries will crush approximately 300,000
tons of material for reuse on the I-405 project.

Ned Racine