A. Scope:
1. The performance standards of this section are general grading performance requirements. A companion grading design manual elaborates minimum performance standards referenced by this section and includes nonregulatory guidelines for superior grading performance.
2. The grading design manual shall be adopted and amended in accordance with Section 18.01.070 (General Provisions).* The commission may hold the preliminary and public hearings concurrently. The technical review committee (refer to Section 18.99.040, Review Committees) shall provide a recommendation prior to commission public hearing.
B. Site revegetation and stabilization: All graded areas except those to be used for agriculture or livestock purposes, not revegetated, stabilized or constructed on upon expiration of the grading permit shall be revegetated or stabilized within sixty days of permit expiration in accordance with the grading design manual, and furthermore, in cases where the purpose of the grading permit is not met, shall be designed to restore the native vegetative community.
C. Slopes: All exposed cut or fill slopes shall be revegetated or stabilized in accordance with the grading design manual and the approved grading sketch or plan.
D. Terracing: Terracing to control surface drainage and debris on cut or fill slopes may be required in accordance with the grading design manual. The width of a terrace shall be a minimum of six feet.
E. Fill: Fill shall be compacted and soil tested in accordance with the grading design manual.
F. Setbacks: The following setbacks shall be increased by the county engineer if considered necessary for safety or stability, or to prevent possible damage from water, soil or debris:
1. Top of Cut Slope: The top of cut slopes shall be made not nearer to a site boundary line than one fifty 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.
2. 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.
3. Buildings: Buildings shall be set back from the toe and top of slopes in accordance with the county building codes (Title 15), Illustration 18.81-3 in Section 18.81.110 or the approved soils report. This shall not reduce the required building setback from property line.
4. Rights-of-way: The required setback of a slope toe adjacent to a public right-of-way may be reduced with the approval of the county engineer, if there will be no adverse effect and:
a. Easements are not required; or
b. Retaining walls are used.
G. Building height: The finished grade and building pads shall be established so that the maximum building height shall not exceed the building height contour line (refer to Illustration 18.81-1, Section 18.81.110).
H. Drainage control systems:
1. Permanent systems:
a. Erosion control shall be constructed and maintained to prevent erosion of slopes, and cleared, brushed, grubbed or graded areas, in accordance with the grading design manual.
b. Where cut slopes are not subject to erosion due to the erosion-resistant character of the native materials, erosion control may be omitted upon approval by the county engineer.
c. Erosion control devices to prevent erosion or sediment deposition on off-site property may be required in accordance with the grading design manual.
d. The shoulders of a paved public or private roadway shall be protected against erosion wherever curbing or constructed spillways are not provided, in accordance with the Grading Design Manual.
e. Surface drainage:
1) Cut and fill slopes shall be provided with approved surface drainage for stability and erosion protection of affected properties in accordance with the Grading Design Manual;
2) Surface drainage interceptors shall be provided at the top of cut and fill slopes where there is surface runoff and erosion potential in accordance with the Grading Design Manual;
3) Drainage slopes to protect foundations shall be provided in accordance with the Grading Design Manual.
f. Subsurface drainage: Subsurface drainage for stability and protection of affected properties from ground water seepage may be required in accordance with the Grading Design Manual.
2. Interim systems: Interim drainage control systems shall be provided in accordance with the Grading Design Manual.
I. Import and export of earth material:
1. Loading of earth material shall occur only within the time limits of subsection J of this section, and dust palliatives shall be applied in accordance with the Grading Design Manual.
2. The transportation of earth material on public rights-of-way shall be in a manner that minimizes blowing soil and other hazards.
J. Hours of grading:
1. Grading equipment operation within one-half mile of a structure occupied by humans shall not be conducted between sunset and seven a.m.
2. Normal equipment maintenance involving lights, motors or generators, and occurring within six hundred feet of a structure occupied by humans, shall not be conducted between nine p.m. and seven a.m.
3. The county engineer may allow grading equipment operation or maintenance during other hours if such operations are not detrimental to the health, safety or welfare of the inhabitants of the structure.
4. Permitted hours of operation or maintenance may be shortened by written notice, if the county engineer finds a substantial adverse effect on the health, safety or welfare of the surrounding community.
K. Restriction of vehicles:
1. No vehicles shall be driven over "natural open space areas," as designated on the approved grading sketch or grading plan.
2. Points-of-entry to the site during grading shall be only as designated on the approved grading sketch or grading plan.
3. For Type 2 permits, access roads to the site during grading shall be only as designated on the approved grading plan.
L. Additional requirements:
1. During grading, and until revegetation or stabilization has taken place, dust shall be minimized through application of approved dust controls in accordance with the Grading Design Manual.
2. Public rights-of-way, sidewalks and other improvements shall be maintained during grading in a neat and clean condition, free of loose soil, construction debris and trash.
3. Debris, fill or equipment shall not be stored within a public right-of-way without the written approval of the county engineer.
4. Cut or fill material in excess of that allowed by the grading permit shall be disposed of in accordance with the Grading Design Manual.
(Ord. 1990-61 § 1 (part), 1990; Ord. 1986-187 § 1 (part), 1986)
* Editor's note: Section 2 of Ordinance No. 1990-61 states as follows: "The Grading Design Manual, which is attached to and incorporated in this ordinance as Exhibit A, and which contains technical requirements for grading, is hereby adopted and shall have all of the force and authority of an ordinance. The Grading Design Manual shall not be published as a part of the Pima County Zoning Code, but shall be published as a separate booklet."