§ 26A-09-030. Terrace mining standards.

In addition to the general mining standards set forth in Section 26A-09-010, the following standards shall be applied to terrace mining operations.

(a)

Permit Time Frames for Terrace Mining Operations.

(1)

A mining permit for terrace operations shall be granted for a period not to exceed ten (10) years, at the end of which time it shall expire; provided, however, that any such permit initially granted for more than five (5) years shall expire at the end of five (5) years unless prior thereto the board of supervisors finds that the operation of the reclamation plan is successfully returning the subject property(ies) to productive agriculture, recreation, conservation habitat, or other use as specifically described in the approved reclamation plan.

(2)

All terrace mining activities shall cease within the ten (10) year time frame set forth in the 1994 ARM plan, so that final reclamation of the sites can be completed. No permits shall be issued which authorize mining beyond the ten (10) year time frame. Calculations of the time limits shall be carried out in accordance with the procedures set forth in Section 7.6.1 of the ARM plan. The board of supervisors shall have jurisdiction to hear and decide all disputes regarding the interpretation of this section and shall have the authority to adopt such rules as it deems necessary to implement this section. Notwithstanding the general 10-year time limit requirements listed in this section to complete all terrace mining, up to three (3) years of additional time from date of project approval may be allowed to complete the existing unfinished Phase VI terrace pit pursuant to section 7.6.1 of the ARM plan, subject to obtaining the necessary use permit and reclamation plan approvals. The deadline may be tolled in accordance with Section 26-92-270 of the Sonoma County Code.

(b)

Acreage Restrictions on Terrace Mining. Applications for terrace mining will only be considered for approval if they are located within the designated "mineral resource" areas shown in Figure 7-11 of the ARM plan. The total area excavated pursuant to mining permits approved after adoption of the 1994 ARM plan shall not exceed one hundred (100) acres on each side of the Russian River, two hundred (200) acres in total, nor a yearly total of ten (10) acres on each side of the river. Acreage not mined during any year may be carried over and mined in a subsequent year but not beyond the end of the ten (10) year period. The above restrictions do not apply to or include mining permits approved or vested mining rights recognized by the county prior to adoption of the ARM plan on November 1, 1994.

For the purposes of applying the acreage limits stated above, the area(s) excavated in any year on any site shall be measured at the elevation of the top of groundwater on May 1st of that year and shall consist of the area(s) where the mining has removed all earth materials above that elevation. Required above-water slopes, other mined areas above that elevation, and required marsh and shoal areas at or below that elevation shall not be included in the determination of excavated acreage.

Notwithstanding the general 10-year time limit requirements listed in this section to complete all terrace mining, up to three (3) years of additional time from date of project approval may be allowed to complete the existing unfinished Phase VI terrace pit pursuant to section 7.6.1 of the ARM plan, subject to obtaining the necessary use permit and reclamation plan approvals. The deadline may be tolled in accordance with Section 26-92-270 of the Sonoma County Code.

(c)

Screening and Setbacks. Visual screening of the terrace pits and mining equipment from public roads and uses will be required using shrubs and trees native to the area and berms to the extent feasible. Mining excavation and stockpiles of extracted aggregate are to be set back a minimum of fifty feet (50′) from the MR zone boundary, property boundary, and public roads. Stockpiles are also to be set back a minimum of three hundred feet (300′) from the ordinary high water mark of the river. Screening, crushing, and other processing activities are to be set back a minimum of two hundred feet (200′) from the MR boundary, the property boundary, and public roads and a minimum of three hundred feet (300′) from the ordinary high water mark of the river. Mining excavation shall be set back four hundred fifty feet (450′) from the ordinary high water mark of the river.

(d)

Ancillary Uses. With a use permit, terrace operations may include processing and sales of raw, processed, or recycled earth materials and aggregate products, excluding the manufacture and batching of concrete and asphalt products. Importation of aggregate materials from approved sites under control of the same operator may be allowed with a use permit. No more than ten (10) percent of materials processed or exported from any terrace site in any calendar year, except materials to be recycled, shall be imported from outside the designated terrace mining area.

(e)

Russian River Monitoring Program. Each operation shall annually fund a fair share, as determined by the county, of the Russian River monitoring program administered by the county pursuant to the ARM plan.

(f)

Terrace Mining Below the Groundwater Table. The development and reclamation of terrace pits which involve gravel removal below the top of the groundwater at any time shall conform to the following standards:

(1)

The maximum area of a new pit shall be limited to twenty (20) acres measured at the premining surface;

(2)

The minimum distance between the edge of any new pit and any other new or existing pit shall not be less than four hundred fifty feet (450′), as measured at the pre-mining surface;

(3)

A four hundred fifty foot (450′) buffer shall be maintained between new pits and the Russian River. This setback shall be measured from the edge of pit excavation on the original ground surface to the ordinary high-water mark of the river;

(4)

No deep-pit terrace mining shall take place more than two thousand feet (2,000′) from the ordinary high-water mark of the river;

(5)

Gravel may be extracted to the full depth of the upper gravel deposit, but the blue clay layer or underlying strata may not be mined;

(6)

Deep-pit terrace mining shall not take place on opposite sides of the river at any point where mining sites are directly across from each other;

(7)

Terrace mining operations and reclamation plans which do not meet all of the categorical standards above may not be approved unless it is determined that the proposal would not result in a drop in the water table at any point on adjacent properties of more than one foot. This determination shall be based upon an analysis of potential groundwater impacts using the MODFLOW computer model or similar model of equal or better analytical capability. The analysis shall assume the worst-case combination of existing and planned pit permeability, water extraction by agricultural and municipal wells, and cumulative effects. The four hundred fifty foot (450′) setback from the river specified in subsection (f)(3) of this section cannot be reduced regardless of the results of MODFLOW analysis.

(g)

Handling of Top Soil. Top soil that is removed from the mining area shall be stockpiled and protected for future use. All soils shall be used to reclaim mined sites to crop production, enhance crop production on nearby lands, or otherwise be used in the surface treatment conducted as part of the approved reclamation plan. Each use permit application for terrace mining shall include a soils report and the steps that will be used to remove, store and reuse the soils. The application shall also include a full description of how the physical and nutrient properties of the soil will be maintained and protected until it is returned for productive use.

(h)

Flood Protection and Levees. Stockpiles, processing operations, and ancillary uses located within the 100-year flood plain between November 1st and June 1st shall be designed and operated to prevent on-site and off-site damage from floods. A four hundred fifty foot (450′) setback is required between new terrace pits and the river to minimize the risk of the river channel being diverted into or through the terrace pits in major floods.

(i)

Russian River Gravel Mitigation Fund. All terrace operations shall be required to contribute their fair share to the Russian River Gravel Mitigation Fund or carry out in-lieu mitigations as set forth in board of supervisors Resolution 95-0450, adopted April 11, 1995, or later amendments.

(j)

Groundwater Monitoring. Each operation shall monitor groundwater levels at each terrace pit site and selected monitoring wells in the terrace mining area in the manner and frequency specified in the ARM plan or by site-specific conditions of approval and/or fund the collection and analysis of such data through the Russian River monitoring program.

(Ord. No. 5806 § 1, 2008; Ord. No. 5165 § 1, 1999.)