Moraga Municipal Code Ch. 14.48 Regulations

Unless otherwise recommended in the approved geotechnical engineering or engineering geologic report and approved by the town, excavations and cut slopes shall conform to the provisions of this section. These regulations apply to all grading whether or not a permit is required. All grading should be balanced on site.

(Ord. 210 (part), 2006)

Cuts slopes shall not be steeper than three horizontal to one vertical, except in conform areas where natural slopes are greater. Where steeper slopes are unavoidable, the applicant shall furnish geotechnical engineering or an engineering geology report, or both, certifying that the site has been evaluated and giving an opinion that a cut at a steeper slope will be stable and not create a hazard to public or private property. The town engineer, or geotechnical engineering or geologic consultant may require the excavation slope face be made flatter than three horizontal to one vertical if he or she finds it necessary for stability and safety.

(Ord. 210 (part), 2006)

Cut slopes exceeding thirty (30) feet in vertical height shall have drainage terraces not less than eight feet in width, at vertical intervals not exceeding twenty-five (25) feet, except where only one such terrace is required, it shall be located at mid-height. For cut slopes exceeding sixty (60) feet in vertical height, the drainage terrace near mid-height shall be not less than twelve (12) feet in width. Design and construction of drainage terraces shall conform to the requirements of Sections 14.20.060(E) through (G) of this code. Other drainage methods may be approved by the town as appropriate. Suitable access shall be provided to the drainage terraces to permit proper cleaning and maintenance

(Ord. 210 (part), 2006)

Cut slopes shall be rounded off at the top and toe and shall be contour graded to achieve a natural appearance and to blend and conform to existing terrain.

(Ord. 210 (part), 2006)

Cut slopes shall be set back from property lines and structures as far as necessary to provide for safety of adjacent property, safety of pedestrians and vehicular traffic, required slope rounding, adequate foundation support, required swales, berms and drainage facilities.

Except where special foundation design has been approved by the town, setbacks for structures shall meet the following requirements:

A. Excavations shall be set back from property lines or project boundaries a minimum distance equal to one-fifth the height of the slope. In any circumstance, the minimum distance will be three feet and the maximum will be ten (10) feet.

B. Excavations shall be set back from existing structures:

1. In accordance with subsection A of this section; or

2. If required by the town, permittee shall provide an investigation and report by a geotechnical engineer or certified engineering geologist recommending a setback that demonstrate adherence to the intent of the section. The report is subject to the review and approval by the town.

(Ord. 210 (part), 2006)

Unless otherwise recommended in the approved geotechnical engineering or engineering geologic report and approved by the design review board or town council, embankments, fills and fill slopes shall conform to the provisions of this section.

(Ord. 210 (part), 2006)

Fill slopes shall not be steeper than three horizontal to one vertical, except in conform areas where natural slopes are greater. Where steeper slopes are unavoidable, the applicant shall furnish geotechnical engineering or an engineering geology report, or both, certifying that the site has been evaluated and giving an opinion that a fill at a steeper slope will be stable and not create a hazard to public or private property. The town engineer, or geotechnical engineering or geologic consultant may require the fill slope face be made flatter than three horizontal to one vertical if he or she finds it necessary for stability, safety and aesthetics.

Slopes not compacted in accordance with this chapter shall not exceed five horizontal to one vertical.

(Ord. 210 (part), 2006)

Existing ground surfaces to receive fill material, unless more restrictive recommendations are contained in the geotechnical engineering or engineering geologic report(s), shall:

A. Be prepared to receive fill by removing vegetation, noncomplying topsoil and other unsuitable materials;

B. Scarifying to a depth of eight inches to provide a bond with the new fill;

C. Where slopes are steeper than five vertical to one horizontal and the height is greater than three feet:

1. By benching into competent bedrock and/or other competent soil as determined by the project geotechnical engineer or certified engineering geologist,

2. The bench under the toe of a fill slope steeper than five horizontal to one vertical shall be at least ten (10) feet wide;

D. Fill Slopes shall be tapered into the existing terrain at the toe and shall be rounded off at the top;

E. Fills shall not toe out on slopes steeper than three horizontal to one vertical. A stability analysis shall be performed by the geotechnical engineer or certified engineering geologist to evaluate the global stability of the slope.

(Ord. 210 (part), 2006)

Except as provided in this chapter, all fills shall be compacted throughout their full extent to a minimum of ninety (90) percent relative compaction. Field density shall be determined by the American Society for Testing and Materials (ASTM) D1557 (latest version) test method.

A. Fills to support roadways shall be compacted to a minimum relative density of ninety (90) percent relative compaction for the width of the traveled way plus three feet on each side thereof.

B. Fills not intended to support structures, or streets need not be compacted to these standards if either the town's geotechnical engineering or geologic consultant determines that such compaction is unnecessary as a safety measure. In making this determination, the town's geotechnical engineering or engineering geologic consultant may require that an investigation be made to establish the characteristics of the soil, the amount of settlement to be expected and the suitability of the material for its intended purpose.

(Ord. 210 (part), 2006)

No organic or other reducible material shall be incorporated in fills, except as recommended by the geotechnical engineer or engineering geologist and approved by the town. No rock or similar irreducible material with a maximum dimension greater than six inches shall be buried or placed within forty-eight (48) inches of finished grade where practical.

(Ord. 210 (part), 2006)

Fill slopes exceeding thirty (30) feet in vertical height shall have drainage terraces not less than eight feet in width, at vertical intervals not exceeding twenty-five (25) feet except that where only one such terrace is required, it shall be located at mid-height. For fill slopes exceeding sixty (60) feet in vertical height, the drainage terrace near mid-height shall be not less than twelve (12) feet in width. Design and construction of drainage terraces shall conform to the requirements of Sections 14.20.060 (E) through (G) of this code. Suitable access shall be provided to the drainage terraces to permit proper cleaning and maintenance.

(Ord. 210 (part), 2006)

Fill slopes shall be tapered into the existing terrain at the toe and shall be rounded off at the top.

(Ord. 210 (part), 2006)

Fill slopes shall be set back from property lines, watercourses and structures as follows:

A. The property line of any proposed or existing site or parcel located within the grading project shall be located a minimum of one foot from the top of the slope;

B. Fill slopes shall be set back a minimum of three feet plus one-fifth the vertical height of the slope from the property line with a maximum of twenty (20) feet;

C. Buildings and structures shall be set back from the toe or the top of fill slopes a minimum of four feet plus one-fifth the vertical height of the slope, with a maximum of twenty (20) feet;

D. When fill slopes are located near the site boundary and the adjacent off-site property is developed, special precautions shall be incorporated in the work as the town engineer deems necessary to protect the adjoining property from damage as a result of such grading. The precautions may include, but not be limited to:

1. Additional setbacks,

2. Provisions for retaining or slough walls,

3. Mechanical or chemical treatment of the fill slopes surface to minimize erosion, and

4. Provisions for the control of surface waters;

E. Fills shall be set back from property lines or project boundaries a minimum distance equal to one-half the height of the slope. In any circumstance, the minimum distance will be three feet and the maximum will be twenty (20) feet;

F. Structures shall be set back from fill slopes:

1. A minimum distance equal to one-half the height of the slope. In any circumstance, the minimum distance will be four feet and the maximum will be twenty (20) feet;

2. If required by an investigation and report by a geotechnical engineer or certified engineering geologist recommending a setback that demonstrate adherence to the intent of the section. The report is subject to the review and approval by the town.

(Ord. 210 (part), 2006)

The town may require the submission of a geotechnical report before issuing a building permit for a structure to be placed on any existing fill or embankment or be excepted from the requirement for a permit, or on any other lot or parcel on which critically expansive soils, slide conditions, or other geotechnical or geologic hazard exist or may reasonably be anticipated to exist. If the town determines that the action recommended in this report is likely to prevent structural damage to the proposed structure, the town shall approve the report and the recommended action contained in the report shall become a part of the required construction as a condition of the permit.

(Ord. 210 (part), 2006)

Modifications from the regulations of this chapter may be allowed by the design review board or the town council, if recommended by the town engineer and if determined to provide equivalent safety, stability, and protection against erosion. The applicant must demonstrate equivalency in a report prepared by a geotechnical engineer or certified engineering geologist with the concurrence of the town.

(Ord. 210 (part), 2006)