§ 36.16.020. Agricultural grading.

Agricultural grading shall be designed and constructed in compliance with the following requirements.

A.

General.

1.

Areas of agricultural grading. Agricultural grading shall be limited to the grading area identified and delineated on the approved plans and specifications.

2.

Final contours. Contours, elevations, and shapes of finished surfaces shall be blended with adjacent natural terrain to achieve a consistent grade and natural appearance. Borders of cut slopes and fills shall be rounded off to a minimum radius of five feet (5') to blend with the natural terrain.

3.

MS4 permit. Where agricultural grading is within an MS4 permit boundary, the agricultural grading shall comply with the applicable standards and provisions of the MS4 permit.

B.

Cuts.

1.

Slope. The slope of cut surfaces shall be no greater than two feet (2') horizontal to one foot (1') vertical (fifty percent (50%)), unless a soils report justifies a greater slope.

2.

Terracing and drainage. Terracing and drainage of cuts shall be provided as required by Subsection D.

C.

Fills.

1.

Fill location. Fill shall not be placed on natural slopes greater than two feet (2') horizontal to one foot (1') vertical (fifty percent (50%)).

2.

Surface preparation. Ground surfaces shall be prepared to receive fill by removing vegetation, topsoil, and other unsuitable materials, and scarifying the ground to provide a bond with the fill material.

3.

Benching. Benching into sound bedrock or other competent material, as determined by a civil engineer, shall be required where existing grade is at a slope greater than five feet (5') horizontal to one foot (1') vertical (twenty percent (20%)) and the depth of the fill exceeds five feet (5'). Benching shall be provided in accordance with Figure 36-1, subject also to the following requirements:

a.

A key at least ten feet (10') in width and two feet (2') in depth shall be installed.

b.

The key shall be installed at least one foot (1') into sound bedrock or other competent material.

c.

The area beyond the toe of the fill shall be sloped for sheet overflow or a non-erosive drain shall be provided.

d.

Cuts for benching and keys shall be accepted by a soils engineer as a suitable foundation for fill prior to the placement of the fill material.

Figure 36-1 Benching Details

4.

Fill material. Fill material shall not include organic, frozen, or other deleterious materials. No rock or similar irreducible material greater than six inches (6") in any dimension shall be included in fills, except where a soils engineer devises a method of placement of larger rock, continuously inspects its placement, and approves fill stability, subject also to the following requirements:

a.

Potential rock disposal areas shall be shown on the plans and specifications.

b.

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

5.

Fill placement. Fills shall be constructed in lifts not exceeding eight inches (8") in depth. Completed fills shall be stable, well-integrated, and bonded to adjacent materials and the materials on which they rest. Fills shall be competent to support anticipated loads and be stable at the design slopes shown on the approved plans and specifications.

6.

Compaction.

a.

Fills below thirty inches (30") from finished grade shall be compacted to a minimum of ninety percent (90%) of maximum dry density, as determined by ASTM D 1557, Modified Proctor, or as specified by a soils engineer.

b.

Fills at or above thirty inches (30") from finished grade shall be compacted to a minimum density necessary for the intended use or as specified by a soils engineer.

7.

Slope. The slope of fill surfaces shall be no greater than two feet (2') horizontal to one foot (1') vertical (fifty percent (50%)), unless a soils report justifies a greater slope.

8.

No net fill in flood-prone urban area or special flood hazard areas. No fill shall be placed in the flood-prone urban area or any special flood hazard area, unless prior to permit issuance an analysis comparing the pre-development and proposed post-development site topography demonstrates that no reduction in flood storage capacity within the special flood hazard area will result from the fill placement and related improvements, and prior to the permit being finaled an analysis comparing the pre-development and as-built topography confirms that no reduction in flood storage capacity within the special flood hazard area has resulted from the fill placement and related improvements.

9.

Terracing and drainage. Terracing and drainage of fills shall be provided as required by Subsection D.

D.

Terracing and drainage of cuts and fills. Terracing and drainage of cuts and fills shall be designed and constructed to ensure the integrity of the cuts and fills. Unless otherwise justified by a soils report, terracing and drainage of cuts and fills with surface slopes greater than three feet (3') horizontal to one foot (1') vertical (thirty-three percent (33%)) shall comply with the following requirements. Additional requirements applicable to the provision of drainage facilities and systems are established by Section 36.16.030.B.

1.

Terraces. Terraces shall be established on cut and fill slopes to control surface drainage and debris. Suitable access shall be provided to permit proper cleaning and maintenance of terraces.

a.

For cut and fill slopes up to thirty feet (30') in vertical height, terraces need not be provided.

b.

For cut and fill slopes greater than thirty feet (30') and up to sixty feet (60') in vertical height, one (1) terrace at least six feet (6') in width shall be established at mid-height.

c.

For cut and fill slopes greater than sixty feet (60') and up to one hundred twenty feet (120') in vertical height, terraces at least six feet (6') in width shall be established at not more than 30-foot intervals or one (1) terrace at least twelve feet (12') in width shall be established at mid-height.

d.

For cut and fill slopes greater than one hundred twenty feet (120') in vertical height, terrace widths and spacing shall be designed by a civil engineer.

2.

Terrace drainage.

a.

Swales or ditches. Swales or ditches shall be provided on terraces, and shall:

(1)

Have a minimum gradient of twenty feet (20') horizontal to one foot (1') vertical (five percent(5%));

(2)

Be paved with reinforced concrete not less than three inches (3") in thickness, or with other materials suitable to the application; and

(3)

Have a minimum depth of one foot (1') and a minimum width of five feet (5').

b.

Limitation on single run of swale or ditch. A single run of swale or ditch shall not collect runoff from a tributary area exceeding thirteen thousand five hundred (13,500) square feet (projected) without discharging into a down drain.

3.

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

4.

Surface interceptor drains. Surface interceptor drains shall be installed along the top of all cut and fill slopes receiving drainage from a tributary width greater than forty feet (40'), measured horizontally upslope. The drains shall be paved with reinforced concrete not less than three inches (3") in thickness, or with other materials suitable to the application. The drains shall be designed in compliance with the Flood Control Design Criteria Manual, or superseding document, for the 100-year design discharge. This surface interceptor drains requirement shall not apply to outslope constructed roadways designed to prevent the concentration of stormwater runoff, provided that the stability of the cut and fill slope is maintained.

E.

Setbacks. Cut and fill slopes shall be set back from property lines in compliance with the following requirements. Setback dimensions shall be measured perpendicular to the property line and shall be as shown in Figure 36-2.

1.

Top of slope. The setback at the top of a slope shall be not be less than that shown in Figure 36-2, or than is required to accommodate any required surface interceptor drains, whichever is greater.

2.

Toe of slope. The setback at the toe of a slope shall not be less than that shown in Figure 36-2.

Figure 36-2 Cut and Fill Slope Setback Requirements

F.

Protection of footings, buildings, and structures. Footings that 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 the building or structure is capable of withstanding the additional loads caused by the fill or surcharge. The rights of adjacent affected property owners shall be as set forth in Civil Code section 832.

(Ord. No. 6219 , § II(Exh. B), 12-19-2017)