San Luis Obispo County Municipal Code Ch. 19.12 Grading and Excavation

The purpose of this appendix is to safeguard life, limb, property, and the public welfare by regulating grading on private property.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

The rules and regulations to control excavation, grading, and earthwork construction, including fills and embankments, are contained in Titles 22 and 23 of the County Code. Where provisions of Title 19 conflict with provisions in Titles 22 or 23, the provisions in Titles 22 and 23 shall prevail.

The standards listed below are recognized standards and as such are not adopted as part of this code.

Testing:

1.1 ASTM D 1557, Moisture-density Relations of Soils and Soil Aggregate Mixtures

1.2 ASTM D 1556, In Place Density of Soils by the Sand-Cone Method

1.3 ASTM D 2167, In Place Density of Soils by the Rubber-Balloon Method

1.4 ASTM D 2937, In Place Density of Soils by the Drive-Cylinder Method

1.5 ASTM D 2922 and D 3017, In Place Moisture Contact and Density of Soils by Nuclear Methods

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

Except as specified in Titles 22 (Land Use Ordinance) and 23 (Coastal Zone Land Use Ordinance) of the County Code, no person shall do any grading without first having obtained a grading permit from the building official.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

Whenever the building official determines that any existing excavation or embankment or fill on private property has become a hazard to life and limb, or endangers property, or adversely affects the safety, use or stability of a public way or drainage channel, the owner of the property upon which the excavation or fill is located, or other person or agent in control of said property, upon receipt of notice in writing from the building official, shall within the period specified therein repair or eliminate such excavation or embankment so as to eliminate the hazard and be in conformance with the requirements of this code.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) Grading permit application contents are as specified in Section 22.52.050 of the Land Use Ordinance and Section 23.05.020 et seq. of the Coastal Zone Land Use Ordinance.

(b) Grading is designated as specified in Section 22.52.060 of the Land Use Ordinance and Section 23.05.020 et seq. of the Coastal Zone Land Use Ordinance.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) Application for a grading permit shall be accompanied by two sets of plans and specifications, and supporting data consisting of a soils engineering report and engineering geology report. The plans and specifications shall be prepared and signed by an individual licensed by the state to prepare such plans or specifications when required by the building official.

(b) Specifications shall contain information covering construction and material requirements.

(c) Plans shall be drawn to scale upon substantial paper and shall be of sufficient clarity to indicate the nature and extent of the work proposed and show in detail that they will conform to the provisions of this code and all relevant laws, ordinances, rules and regulations. The first sheet of each set of plans shall give location of the work, the name and address of the owner and the person by whom they were prepared.

(d) The plans shall include the following information:

(1) General vicinity of the proposed site.

(2) Property limits and accurate contours of existing ground and details of terrain and area drainage.

(3) Limiting dimensions, elevations, or finish contours to be achieved by the grading and proposed drainage channels and related construction.

(4) Detailed plans of all surface and subsurface drainage devices, walls, cribbing, dams, and other protective devices to be constructed with, or as a part of, the proposed work together with a map showing the drainage area and the estimated runoff of the area served by any drains, including historic onsite drainage flow pattern, final drainage flow patterns offsite, and route to final discharge into public facility.

(5) Location of any buildings or structures on the property where the work is to be performed and the location of any buildings or structures on land of adjacent owners which are within fifteen feet of the property or which may be affected by the proposed grading operations.

(6) Recommendations included in the soils engineering report and the engineering geology report shall be incorporated in the grading plans or specifications. When approved by the building official, specific recommendations contained in the soils engineering report and the engineering geology report, which are applicable to grading, may be included by reference.

(7) The dates of the soils engineering and engineering geology reports together with the names, addresses, and phone numbers of the firms or individuals who prepared the reports.

(e) Soils Engineering Report. The soils engineering report required by Section 1803 shall include data regarding the nature, distribution, and strength of existing soils, conclusions, and recommendations for grading procedures and design criteria for corrective measures, including buttress fills, when necessary, and opinion on adequacy for the intended use of sites to be developed by the proposed grading as affected by soils engineering factors, including the stability of slopes.

(f) Engineering Geology Report. The engineering geology report required by Section 1803 shall include an adequate description of the geology of the site, conclusions, and recommendations regarding the effect of geologic conditions on the proposed development, and opinion on the adequacy for the intended use of sites to be developed by the proposed grading, as affected by geologic factors.

(g) Liquefaction Study. The building official may require a geotechnical investigation in accordance with Sections 1803.1 and 1803.2 when, during the course of an investigation, all of the following conditions are discovered, the report shall address the potential for liquefaction:

(1) Shallow ground water, fifty feet or less.

(2) Unconsolidated sandy alluvium.

(3) Seismic Design Category C—F.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) Each application for a grading permit shall be accompanied by a plan in sufficient clarity to indicate the nature and extent of the work. The plans shall give the location of the work, the name of the owner, and the name of the person who prepared the plan. The plan shall include the following information:

(1) General vicinity of the proposed site.

(2) Limiting dimensions and depth of cut and fill.

(3) Location of any buildings or structures where work is to be performed, and the location of any buildings or structures within fifteen feet of the proposed grading.

(b) Issuance. The provisions of Section 105 are applicable to grading permits. The building official may require that grading operations and project designs be modified if delays occur which incur weather-generated problems not considered at the time the permit was issued.

The building official may require professional inspection and testing by the soils engineer. When the building official has cause to believe that geologic factors may be involved, the grading will be required to conform to engineered grading.

(Ord. No. 3400, § 1, 11-19-19)

Fees shall be assessed as set forth in the fee schedule adopted by the jurisdiction and fees shall be assessed as specified in Section 22.52.210 of the Land Use Ordinance and Section 22.05.058 of the Coastal Zone Land Use Ordinance.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

The building official may require bonds, as specified in Section 22.52.210 of the Land Use Ordinance and Section 23.05.032.c of the Coastal Zone Land Use Ordinance.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) General. Unless otherwise recommended in the approved soils engineering or engineering geology report, cuts shall conform to the provisions of this section. In the absence of an approved soils engineering report, these provisions may be waived for minor cuts not intended to support structures.

(b) Slope. The slope of cut surfaces shall be no steeper than is safe for the intended use and shall be no steeper than one unit vertical in two units horizontal (fifty percent slope) unless the permittee furnishes a soils engineering or an engineering geology report, or both, stating that the site has been investigated and giving an opinion that a cut at a steeper slope will be stable and not create a hazard to public or private property.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) General. Unless otherwise recommended in the approved soils engineering report, fills shall conform to the provisions of this section. In the absence of an approved soils engineering report, these provisions may be waived for minor fills not intended to support structures.

(b) Preparation of Ground. Fill slopes shall not be constructed on natural slopes steeper than one unit vertical in two units horizontal (fifty percent slope). The ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, topsoil, and other unsuitable materials scarifying to provide a bond with the new fill and, where slopes are steeper than one unit vertical in five units horizontal (twenty percent slope) and the height is greater than five feet, by benching into sound bedrock or other competent material as determined by the soils engineer. The bench under the toe of a fill on a slope steeper than one unit vertical in five units horizontal (twenty percent slope) shall be at least ten feet wide. The area beyond the toe of fill shall be sloped for sheet overflow or a paved drain shall be provided. When fill is to be placed over a cut, the bench under the toe of fill shall be at least ten feet wide but the cut shall be made before placing the fill and acceptance by the soils engineer or engineering geologist or both as a suitable foundation for fill.

(c) Fill Material. Detrimental amounts of organic material shall not be permitted in fills. Except as permitted by the building official, no rock or similar irreducible material with a maximum dimension greater than twelve inches shall be buried or placed in fills.

Exception: The building official may permit placement of larger rock when the soils engineer properly devises a method of placement, and continuously inspects its placement and approves the fill stability. The following conditions shall also apply:

(1) Prior to issuance of the grading permit, potential rock disposal areas shall be delineated on the grading plan.

(2) Rock sizes greater than twelve inches in maximum dimension shall be ten feet or more below grade, measured vertically.

(3) Rocks shall be placed so as to assure filling of all voids with well-graded soil.

(d) Compaction. All fills shall be compacted to a minimum of ninety percent of maximum density.

(e) Slope. The slope of fill surfaces shall be no steeper than is safe for the intended use. Fill slopes shall be no steeper than one unit vertical in two units horizontal (fifty percent slope).

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) General. Cut and fill slopes shall be set back from site boundaries in accordance with this section. Setback dimensions shall be horizontal distances measured perpendicular to the site boundary. Setback dimensions shall be as shown in Figure A-1808.7.

(b) Top of Cut Slope. The top of cut slopes shall not be made nearer to a site boundary line than one-fifth of the vertical height of cut with a minimum of two feet and a maximum of ten feet. The setback may need to be increased for any required interceptor drains.

(c) Toe of Fill Slope. The toe of fill slope shall be made not nearer to the site boundary line than one-half the height of the slope with a minimum of two feet and a maximum of twenty feet. Where a fill slope is to be located near the site boundary and the adjacent off-site property is developed, special precautions shall be incorporated in the work as the building official deems necessary to protect the adjoining property from damage as a result of such grading. These precautions may include but are not limited to:

(1) Additional setbacks.

(2) Provision for retaining or slough walls.

(3) Mechanical or chemical treatment of the fill slope surface to minimize erosion.

(4) Provisions for the control of surface waters.

(d) Modification of Slope Location. The building official may approve alternate setbacks. The building official may require an investigation and recommendation by a qualified engineer or engineering geologist to demonstrate that the intent of this section has been satisfied.

Figure A-1808.7 [Figure: Figure A-1808.7]

FOUNDATIONS ON OR ADJACENT TO SLOPES: The placement of buildings and structures on or adjacent to slopes steeper than three horizontal one vertical shall be in accordance with the following illustrations. The provisions are intended to provide protection for the building and from slope drainage, erosion and mudflow, loose slope debris, shallow slope failures, and foundation movement (California Building Code 1804).

Alternate design may be provided by architect/engineer with soil engineer's analysis and written approval.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

The requirements for protection of adjacent property and depth to which protection is required shall be as defined by prevailing law. Where not defined by law, the following shall apply: Any persons making or causing an excavation to be made to a depth of twelve feet (3658 mm) or less below the grade shall protect the excavation so that the soils of the adjoining property will not cave in or settle, but shall not be liable for the expense of underpinning or extending the foundation of the buildings on adjoining properties when the excavation is not in excess of twelve feet (3658 mm) in depth. Before commencing the excavation, the person making or causing the excavation to be made shall notify in writing the owners of adjoining buildings not less than ten days before such excavation is to be made and that the excavation is to be made that adjoining buildings should be protected.

The owners of the adjoining properties shall be given access to the excavation for the purpose of protecting such adjoining buildings.

Any person making or causing an excavation to be made exceeding twelve feet (3658 mm) in depth below the grade shall protect the excavation so that the adjoining soil will not cave in or settle and shall extended the foundation of any adjoining buildings below the depth of twelve feet (3658 mm) below grade at the expense of the person causing or making the excavation. The owner of the adjoining buildings shall extend the foundation of these buildings to a depth of twelve feet (3,658 mm) below grade at such owner's expense, as provided in the preceding paragraph.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) General. Unless otherwise indicated on the approved grading plan, drainage facilities and terracing shall conform to the provisions of this section for cut or fill slopes steeper than one unit vertical in three units horizontal (33.3% slope).

(b) Terrace. Terraces at least six feet in width shall be established at not more than 30-foot vertical intervals on all cut or fill slopes to control surface drainage and debris except that where only one terrace is required, it shall be at mid-height. For cut or fill slopes greater than sixty feet and up to one hundred twenty feet in vertical height, one terrace at approximately mid-height shall be twelve feet in width. Terrace widths and spacing for cut and fill slopes greater than one hundred twenty feet in height shall be designed by the civil engineer and approved by the building official. Suitable access shall be provided to permit proper cleaning and maintenance.

Swales or ditches on terraces shall have a minimum gradient of five percent and must be paved with reinforced concrete not less than three inches in thickness or an approved equal paving. They shall have a minimum depth at the deepest point of one foot and a minimum paved width of five feet.

A single run of swale or ditch shall not collect runoff from a tributary area exceeding thirteen thousand five hundred square feet (projected) without discharging into a down drain.

(c) Subsurface Drainage. Cut and fill slopes shall be provided with subsurface drainage as necessary for stability.

(d) Disposal. All drainage facilities shall be designed to carry waters to the nearest practicable drainage way approved by the building official or other appropriate jurisdiction as a safe place to deposit such waters. Erosion of ground in the area of discharge shall be prevented by installation of nonerosive down drains or other energy dissipation devices.

The permittee shall incorporate design elements to retain the required drainage volumes and minimize the disposal of waters for regulated projects as required by Central Coast Regional Water Quality Control Board Order R3-2013-0032, and Section 19.11.050.

The gradient from the building pad shall be a minimum of five percent toward approved drainage facilities, unless waived by the building official.

Exception: The gradient from the building pad may be one percent if all of the following conditions exist throughout the permit area:

(1) No proposed fills are greater than ten feet in maximum depth.

(2) No proposed finish cut or fill slope faces have a vertical height in excess of ten feet.

(3) No existing slope faces, which have a slope face steeper than one unit vertical in ten units horizontal (ten percent slope), have a vertical height in excess of ten feet.

(e) Interceptor Drains. Paved interceptor drains shall be installed along the top of all cut slopes where the tributary drainage area above slopes toward the cut and has a drainage path greater than forty feet measured horizontally. Interceptor drains shall be paved with a minimum of three inches of concrete or gunite and reinforced. They shall have a minimum depth of twelve inches and a minimum paved width of thirty inches measured horizontally across the drain. The slope of drain shall be approved by the building official.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) Slopes. The top, toe, and faces of cut and fill slopes shall be prepared and maintained to control against erosion. This control shall consist of approved best management practices (BMPs) shown on the grading plans and the stormwater pollution prevention plan as applicable. The protection for the slopes shall be installed as soon as practicable and prior to calling for final approval.

(b) A condition compliance monitoring case shall be required whenever there are post construction structural control measures required to be operated and maintained after the construction permit is finaled (Section 19.11.070).

(c) No grading or structure inspections shall be made unless required BMPs are in place. A pre-construction inspection must be conducted prior to the commencement of land disturbance year round.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) General. Grading operations for which a permit is required shall be subject to inspection by the building official. Professional inspection of grading operations shall be provided by the civil engineer, soils engineer, and the engineering geologist retained to provide such services and approved by the building official in accordance with Section 19.12.060 for engineered grading and as required by the building official for regular grading.

(b) Civil Engineer. The civil engineer shall provide professional inspection within such engineer's area of technical specialty, which shall consist of observation and review as to the establishment of line, grade and surface drainage of the development area. If revised plans are required during the course of the work they shall be prepared by the civil engineer.

(c) Soils Engineer. The soils engineer shall provide professional inspection within such engineer's area of technical specialty, which shall include observation during grading and testing for required compaction. The soils engineer shall provide sufficient observation during the preparation of the natural ground and placement and compaction of the fill to verify that such work is being performed in accordance with the conditions of the approved plan and the appropriate requirements of this chapter. Revised recommendations relating to conditions differing from the approved soils engineering and engineering geology reports shall be submitted to the permittee, the building official and the civil engineer.

(d) Engineering Geologist. The engineering geologist shall provide professional inspection within such engineer's area of technical specialty, which shall include professional inspection of the bedrock excavation to determine if conditions encountered are in conformance with the approved report. Revised recommendations relating to conditions differing from the approved engineering geology report shall be submitted to the soils engineer.

(e) Permittee. The permittee shall be responsible for the work to be performed in accordance with the approved plans and specifications and in conformance with the provisions of this code, and the permittee shall engage consultants, if required, to provide professional inspections on a timely basis. The permittee shall act as a coordinator between the consultants, the contractor and the building official. In the event of changed conditions, the permittee shall be responsible for informing the building official of such change and shall provide revised plans for approval.

(f) Building Official. The building official shall inspect the project at the various stages of work requiring approval to determine that adequate control is being exercised by the professional consultants.

(g) Notification of Noncompliance. If, in the course of fulfilling their respective duties under this chapter, the civil engineer, the soils engineer or the engineering geologist finds that the work is not being done in conformance with this chapter or the approved grading plans, the discrepancies shall be reported immediately in writing to the permittee and to the building official.

(h) Transfer of Responsibility. If the civil engineer, the soils engineer, or the engineering geologist of record is changed during grading, the work shall be stopped until the replacement has agreed in writing to accept their responsibility within the area of technical competence for approval upon completion of the work. It shall be the duty of the permittee to notify the building official in writing of such change prior to the recommencement of such grading.

(Ord. No. 3343, § 1, 12-6-16; Ord. No. 3400, § 1, 11-19-19)

(a) Final Reports. Upon completion of the rough grading work and at the final completion of the work, the following reports and drawings and supplements thereto are required for engineered grading or when professional inspection is performed for regular grading, as applicable.

(1) An as-built grading plan prepared by the civil engineer retained to provide such services in accordance with Section 1803 & 1804 showing original ground surface elevations, as-graded ground surface elevations, lot drainage patterns, and the locations and elevations of surface drainage facilities and of the outlets of subsurface drains. As-constructed locations, elevations, and details of subsurface drains shall be shown as reported by the soils engineer. Civil engineers shall state that to the best of their knowledge the work within their area of responsibility was done in accordance with the final approved grading plan.

(2) A report prepared by the soils engineer retained to provide such services in accordance with Section 1803 & 1804, including locations and elevations of field density tests, summaries of field and laboratory tests, other substantiating data, and comments on any changes made during grading and their effect on the recommendations made in the approved soils engineering investigation report. Soils engineers shall submit a statement that, to the best of their knowledge, the work within their area of responsibilities is in accordance with the approved soils engineering report and applicable provisions of this chapter.

(3) A report prepared by the engineering geologist retained to provide such services in accordance with Section 1803 & 1804, including a final description of the geology of the site and any new information disclosed during the grading and the effect of same on recommendations incorporated in the approved grading plan. Engineering geologists shall submit a statement that, to the best of their knowledge, the work within their area of responsibility is in accordance with the approved engineering geologist report and applicable provisions of this chapter.

(4) The grading contractor shall submit in a form prescribed by the building official a statement of conformance to said as-built plan and the specifications.

(b) Notification of Completion. The permittee shall notify the building official when the grading operation is ready for final inspection. Final approval shall not be given until all work, including installation of all drainage facilities and their protective devices, and all erosion-control measures have been completed in accordance with the final approved grading plan, site stabilization is complete, and the required reports have been submitted.

(Ord. No. 3400, § 1, 11-19-19)