Part 6 — Design Standards

Excavations shall be constructed or protected so that they do not endanger life or property. (Ord. 5056-B, 2000)

The slope of cut surfaces of permanent excavations shall not be steeper than two horizontal to one vertical exclusive of terraces and exclusive of rounding described herein. Steeper slopes will be permitted in competent bedrock provided such slope inclinations are in accordance with recommendations contained in the geotechnical or geological report. The bedding planes, foliation planes or principal joint sets in any formation when dipping towards the cut face shall not be daylighted by the cut slope unless the soils and geologic investigations contain recommendations for steeper cut slopes. Cut slopes shall be rounded into the existing terrain to produce a contoured transition from cut face to natural ground. (Ord. 5056-B, 2000)

Fills shall be constructed in layers. The loose thickness of each layer of fill material before compaction shall not exceed eight inches. Completed fills shall be stable masses of wellintegrated material bonded to adjacent materials and to the materials on which they rest. Fills shall be competent to support anticipated loads and be stable at the design slopes shown on the plans. Proper surface and subsurface drainage and other appropriate measures shall be taken to ensure the continuing integrity of fills. Earth materials shall be used which have no more than minor amounts of organic substances and have no rock or similar irreducible material with a maximum dimension greater than 12 inches. Larger material may be used with the approval of the community development resource agency and the geotechnical engineer. (Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B, 2006)

All fills shall be compacted throughout their full extent to a minimum of 90% of maximum density as determined by the appropriate Caltrans standard method or other alternate methods approved by the community development resource agency. Tests to determine the density of compacted fills shall be made on the basis of not less than one test for each two-foot vertical lift of the fill but not less than one test for each 1,000 cubic yards of material placed. Additional density tests at a point approximately one foot below the fill slope surface shall be made on the basis of not less than one test for each 1,000 square feet in slope surface but not less than one test for each 10 foot vertical increase of slope height. All tests shall be reasonably uniformly distributed within the fill or fill slope surface. Results of such testing and location of tests shall be presented in the periodic and final reports. Compaction may be less than 90% of maximum density, as determined by the above test, within six inches of the slope surface when such surface material is placed and compacted by a method acceptable to the community development resource agency for the planting of the slopes. Compaction of temporary stockpile fills, to be used for a period of not greater than six months, shall not be required, except where the community development resource agency determines that compaction is necessary as a safety

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Placer County, CA

BUILDING AND DEVELOPMENT

§ 15.48.520

§ 15.48.580

measure to aid in preventing saturation, sliding, or erosion of the fill. (Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B, 2006)

The natural ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, top soil, and other unsuitable material, and where slopes are six horizontal to one vertical or steeper, by benching into competent material in a manner acceptable to the community development resource agency. The keyway under the toe, if specified, shall be at least 15 feet wide.

(Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B, 2006)

The slope of permanent fills shall not be steeper than two horizontal to one vertical exclusive of terraces and exclusive of roundings described herein, unless a soils report supports a steeper slope, but shall not exceed one and one-half horizontal to one vertical unless the fill is reinforced as recommended by the geotechnical engineer. The community development resource agency may require that the fill be constructed with an exposed surface flatter than two horizontal to one vertical or may require such other measures as he or she deems necessary for stability and safety. (Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B, 2006)

Footings which may be affected by any excavation shall be underpinned or otherwise protected against settlement and shall be protected against lateral movement. Fills or other surcharge loads shall not be placed adjacent to any building or structure unless such building or structure is capable of withstanding the additional loads caused by such fill or surcharge. The rights of coterminous owners shall be as set forth in Section 832 of the Civil Code of the state of California.

(Ord. 5056-B, 2000)

Unless otherwise recommended in a soil or geologic investigation report, Appendix 33 of the latest county adopted version of the Uniform Building Code shall be used for establishing setbacks for property boundaries, buildings and structures other than fences and retaining walls. (Ord. 5056-B, 2000; Ord. 5407-B § 15, 2006)

Any drainage structure(s) or device(s) carrying surface water runoff required by this article shall be designed and constructed in accordance with standards herein, the current Placer County flood control and water conservation district stormwater management manual, the West Placer and East Placer Storm Water Quality Design Manuals, where applicable, and criteria authorized by the agency director.

(Ord. 5056-B, 2000; Ord. 5407-B § 16, 2006; Ord. 5824-B § 4, 2016; Ord. 5917-B § 2, 2018)

All drainage facilities shall be designed and engineered to prioritize the retention, detention, and

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Placer County, CA § 15.48.580

PLACER COUNTY CODE

§ 15.48.630

infiltration of water on-site and be consistent with, where applicable, the West Placer and East Placer Storm Water Quality Design Manuals. Any surface and subsurface waters not able to be retained, detained, and/or infiltrated on-site shall be carried to the nearest adequate street, storm drain, natural watercourse, or other juncture.

(Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5824-B § 5, 2016; Ord. 5917-B § 3, 2018)

All areas shall be graded and drained so that drainage will not cause erosion or endanger the stability of any cut or fill slope or any building or structure. (Ord. 5056-B, 2000)

When surface drainage is discharged onto any adjoining property, it shall be discharged in such a manner that it will not cause erosion or endanger any cut or fill slope or any building or structure. (Ord. 5056-B, 2000)

Terraces at least eight feet in width shall be established at not more than 25 feet in height intervals for all cut and fill slopes exceeding 30 feet in height. Where only one terrace is required, it shall be at approximately mid-height. Suitable access shall be provided to permit proper cleaning and maintenance of terraces and terrace drains. Swales or ditches on terraces shall have a minimum depth of one foot, a minimum longitudinal grade of four percent, a maximum longitudinal grade of 12%. Down-drains or drainage outlets shall be provided at approximately 300 foot intervals along the drainage terrace. Down-drains and drainage outlets shall be of approved materials and of adequate capacity to convey the intercepted waters to the point of disposal. If the drainage discharges onto natural ground, adequate erosion protection shall be provided.

(Ord. 5056-B, 2000)

Cut and fill slopes shall be provided with surface and/or subsurface drainage as necessary for stability.

(Ord. 5056-B, 2000)

The following shall apply to the control of erosion and sediment from grading operations:

• A. Grading plans shall be designed with long-term erosion and sediment control as a primary consideration. Erosion prevention and source control are to be emphasized over sediment controls and treatment.

• B. Grading operations shall provide erosion and sediment control measures, except upon a clear demonstration, to the satisfaction of the community development resource agency that at no stage of the work will there be any substantial risk of increased sediment discharge from the site. Temporary mulch, revegetation, or other stabilization methods shall be applied to areas where permanent revegetation or landscaping cannot be immediately

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Placer County, CA

BUILDING AND DEVELOPMENT

§ 15.48.630

§ 15.48.650

implemented. Unless otherwise exempted in this article, grading activity must be scheduled to ensure completion or winterization by October 15th of each year.

• C. Grading activity shall be conducted such that the smallest practicable area of erodible land is exposed at any one time during grading operations and the time of exposure is minimized. Land disturbance shall be limited to the minimum area necessary for construction.

• D. Natural features, including vegetation, terrain, watercourses, aquatic resources, the stream system, and similar resources shall be protected and preserved wherever possible. Units of grading shall be dearly defined and marked to prevent damage by construction equipment.

• E. Permanent vegetation and structures for erosion and sediment control shall be installed as soon as possible.

• F. Adequate provision shall be made for effective maintenance of temporary and permanent erosion and sediment control structures and vegetation. Sediment and other constructionrelated wastes shall be retained and properly managed on the site or properly disposed of off site.

• G. No topsoil shall be removed from the site unless otherwise directed or approved by the community development resource agency. Topsoil overburden shall be stockpiled and redistributed where appropriate within the graded area after rough grading to provide a suitable base for seeding and planting. Runoff from the stockpiled area shall be controlled to prevent erosion and resultant sedimentation of receiving water.

• H. Runoff shall not be discharged from the site in quantities or at velocities substantially above those which occurred before grading except into drainage facilities, whose design has been specifically approved by the community development resource agency.

• I. The permittee shall take reasonable precautions to ensure that vehicles do not track or spill earth materials into public streets and shall immediately remove such materials if this occurs.

• J. All cut and fill slopes shall be adequately stabilized to prevent erosion and failure through temporary and permanent means.

• K. Control measures shall be employed to prevent transport of dust off the project site or into any drainage course or water body.

• (Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B § 17, 2006; Ord. 6042-B § 1, 2020)

Should increased sediment discharge occur or become imminent, the permittee shall take all necessary steps to control or reduce such discharge. Such steps may include construction of additional facilities or removal or alteration of facilities required by approved erosion and sediment control plans. Facilities removed or altered shall be restored as soon as possible afterward or appropriate changes in the plan shall be immediately required pursuant to this article. The permittee shall take prompt action to resolve emergency problems; otherwise the community development resource agency may institute abatement proceedings pursuant to provisions of Section 15.48.700(B) of this article.

(Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B § 18, 2006)

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Placer County, CA

PLACER COUNTY CODE

§ 15.48.650

§ 15.48.650

Erosion and sediment control plans prepared pursuant to this article shall comply with all of the following:

• A. The erosion and sediment control plan need not be a separate sheet if all facilities and measures can be shown on the grading sheets without obscuring the clarity of either the grading plan or the erosion and sediment control plan.

• B. An erosion and sediment control plan shall be required whenever:

  1. The graded portion of the site includes more than 10,000 square feet of area having a slope greater than 10%;

  2. Clearing and grubbing of areas of one acre or more regardless of slope;

  3. There is a significant risk that more than 2,500 square feet will be unprotected or inadequately protected from erosion during any portion of the rainy season;

  4. Grading will occur within 50 feet of any watercourse when such watercourse is located outside of the PCCP boundary (Section 19.10.050). When the watercourse is located within the PCCP boundary, an erosion and sediment control plan will be required for any grading that occurs within the stream system boundary.

  5. The community development resource agency determines that the grading will or may pose a significant erosion, or sediment discharge hazard for any reason; or

  6. The site is located within the Tahoe Basin.

• C. Except as provided in Section 15.48.120 of this article, sediment and erosion control measures must be in place or be capable of being placed within 24 hours, in the opinion of the agency director, by October 15th. The agency director may require suspension of any and all grading activities between October 15 and May 1 without prior notice.

• D. The applicant shall submit with the erosion and sediment control plans a detailed cost estimate covering this work.

• E. Erosion and sediment control plans shall include an effective revegetation program to stabilize all disturbed areas, which will not be otherwise protected. All such areas where grading has been completed between April 1 and October 15 shall be planted by November 1st. Graded areas completed at other times of the year shall be planted within 15 days. If revegetation is infeasible or cannot be expected to stabilize an erodible area with assurance during any part of the rainy season and the unstable area exceeds 2,500 square feet, additional erosion and sediment control measures or irrigation of planted slopes may be required as appropriate to prevent increased sediment discharge.

• F. Erosion and sediment control plans shall be designed to prevent increased discharge of sediment at all stages of grading and development from initial disturbance of the ground to project completion. Every feasible effort shall be made to ensure that site stabilization is permanent. Plans shall indicate the implementation period and the stage of construction where applicable.

• G. Erosion and sediment control plans shall comply with the recommendations of the responsible civil engineer, geotechnical engineer, engineering geologist, or landscape

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Placer County, CA

• H. The structural and hydraulic adequacy of all stormwater containment or conveyance facilities shown on the erosion and sediment control plans shall be verified by a civil engineer, and he or she shall so attest on the plans. Sufficient calculations and supporting material to demonstrate such adequacy shall accompany the plans when submitted.

• I. Erosion and sediment control plans shall be designed to meet anticipated field conditions.

• J. Erosion and sediment control plans shall provide for inspection and repair of all erosion and sediment control facilities at the close of each working day during the rainy season and for specific sediment cleanout and vegetation maintenance criteria.

• K. Erosion and sediment control plans shall comply with any and all standards and specifications adopted herein for the control of erosion and sedimentation on grading sites. These standards and specifications shall be in general compliance with the current Erosion and Sediment Control Guidelines for Developing Areas of the Sierras, published by the High Sierra Resource Conservation District.

• (Ord. 5056-B, 2000; Ord. 5373-B, 2005; Ord. 5407-B § 19, 2006; Ord. 6042-B § 1, 2020)

Vehicular ways shall conform to the grading requirements of this article. (Ord. 5056-B, 2000)

Vehicular ways shall be graded and drained in such a manner that will not allow erosion or endanger the stability of any adjacent slope. Surface discharge onto adjoining property shall be controlled in such a manner that it does not cause erosion or endanger existing improvements. Bridges and culverts installed in watercourses may be reviewed by the Placer County Flood Control and Water Conservation district and must be approved by the agency director and any other required permitting agency.

(Ord. 5056-B, 2000; Ord. 5407-B § 20, 2006)

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Placer County, CA