Specifications include, but are not limited to: It is understood that the project consists of the reconstruction of the existing erosion protection structure located on the south, or downstream side of the Interstate 25 Bridge 6625 concrete box culvert. It is understood that the wing walls and base will be removed and replaced with a new concrete outlet chute or a broken-back concrete box culvert, which will outlet into a concrete contra costa basin which will have two baffle blocks, one block will be 2.5 feet in height and the second will be 4.87 feet in height. The contra costa basin will have gabion basket retaining walls and that will outlet into a riprap pad. The outlet chute or broken-back concrete box culvert will be about 30.75 in length. Concrete retaining walls up to about about 16 feet in height will be constructed on either side of the arroyo with a concrete chute. The concrete contra costa basin will be about 45 feet in length with a gabion basket retaining walls on the order of about 10 feet in height on either side. The riprap pad will be about 35 feet in length with the same gabion basket retaining walls. The existing ground around the outlet structure will slope down towards the arroyo at a 3 horizontal to 1 vertical slope.
