The Presidio Trust and National Park Service are working cooperatively to remove several landfills from the coastal bluffs overlooking the Pacific Ocean at the south side of the Golden Gate above north Baker Beach.
AIS Construction of Carpinteria, Calif., is doing the work.
From the 1930s through the 1960s, the U.S. Army disposed of waste soil and building debris on the tops of the bluffs and over the cliffs. The waste material covers sensitive ecological habitat and obscures parts of the historical coastal artillery batteries.
The site and project requirements presented a number of interesting challenges. Among these was the need to excavate class 1 hazardous materials from the cliff face and transport them by conveyors up 40-degree slopes over a distance of 1,200 linear ft. (365 m).
The use of the spider climbing excavators and the ALLU SM 2-12 processing attachment allowed the Presidio Trust and National Park Service to preclassify the excavated material and increase the efficiency of the conveyor system. Because the attachment was able to screen/crush the oversized debris, the conveyors were able to carry a more consistent load.
The ALLU processing attachment allowed the material to classify at the point of excavation, thus eliminating the unnecessary removal of uncontaminated, native rock. This process equated to a significant savings to the customer, according to Andy Sheaffer, president of AIS Construction.
Once the removal work is complete, improved recreational trails will be constructed, military fortifications will be restored and natural area restoration and volunteer stewardship will begin as a part of the Trails Forever initiative.
For more information, visit www.allu.net.