CDFW has executed Streambed Alteration Agreement No. 1600-2017-0074-R2, pursuant to section 1602 of the Fish and Game Code to the project Applicant, Hansen Bros. Enterprises.
The project consists of the yearly channel realignment of Greenhorn Creek from a braided, meandering streambed into a single channel in order to harvest the sand and gravel from the creek, during dry conditions. The realignment is accomplished by using an excavator to dig a new channel, starting at the bottom of the new channel and installed at an upstream direction. The channel will be dug in the sand and gravel, not into the dirt, and will utilize as much of the existing meandering braided channel as possible. No vegetation will be removed by this realignment.
One 72" diameter culvert will be in place where the Creek is adjacent to the plant area on the north (upstream) edge of the plant area. Depending on the location of the stream at the time of the channel realignment (significant meandering vs. predominantly one side of the stream bed), there may be a need fora smaller 12" to 24" diameter culverts, usually towards the upper end of the project. The location of the additional culverts is determined each year based on the location of the stream at the time of the channel realignment. The quantity of additional culverts varies each year and is typically between one and ten culverts. The typical culvert length is approx.. 40 feet long. Frequently the 72" diameter culvert near the plant is the only culvert needed.
Depending on the amount of sand and gravel material deposited in the creek bed during the winter high water storm periods and customer demand, the channel realignment could be approx.. 3.5 miles long. The volume of material moved during the trenching process could be approx.. 110,000 cubic yards of sand and gravel per year. The length of the volume of material moved will vary with the amount of materials washed into the creek bed by winter storm run-off and demand for material. The volume and length could be slightly more or substantially less.
Water is pumped from Greenhorn Creek and is used to supplement water used in the washing circuit of the plant. Wash water is recycled and continually reused as much as possible. Water from Greenhorn Creek is also used on an as needed basis for dust control.
Harvesting of sand and gravel is typically completed using self-loading scrapers operating in the dry creek bed. Later in the year, typically in the fall and prior to the rains, the scraper harvesting is augmented by and excavator loading off-hwy haul trucks. Harvesting of material within 25 feet of the channel will cease once ground water is encountered.
The material being harvested is stockpiled, processed and stored at the processing plant, which is located adjacent to Greenhorn Creek.