The city finds and declares that it is necessary to prevent excessive grading of single lots and perimeter lots of multilot developments beyond that necessary for the use and drainage of the site, and also to regulate slopes and retaining walls along property lines. Minimum grading requirements and treatment of slopes at property lines are also to be regulated for the purpose of minimizing adverse environmental effects on surrounding properties. (Prior code § 86001)

   A.   The standards of this chapter shall apply to all land within the city, to control excavation, grading and earthwork construction, including fills and embankments contained in chapter 70 of the uniform building code. Where in any specific case a section of this chapter specifies different requirements than chapter 70 of the uniform building code, the most restrictive shall apply.

   B.   If, in the opinion of the soils engineer, improper drainage from a building or property would result from strict adherence to the grading standards of this chapter for a specified location and soils condition, the building and safety director may approve alternate grading systems, provided that his recommendation is submitted in writing or incorporated in his soils investigation report. (Prior code § 86002)

In addition to the grading permit requirements of chapter 70 of the uniform building code, information on plans shall include the following:

   A.   A map showing the tributary drainage area or areas and estimated runoff, expressed in cubic feet per second, together with supporting calculations signed by a registered engineer;

   B.   The concrete or gunite interceptor and storm drain construction details, with its size, slopes and capacity to be justified by supporting calculations signed by a registered engineer. Seventy eight hundredths of an inch (0.78") per hour, estimated 10-year storm, shall be the minimum criteria for design of such interceptor or storm drains. (Prior code § 86003)

   A.   For the purpose of this chapter, retaining walls shall be essentially vertical, and shall be constructed of concrete, masonry, or wood treated with an approved preservative under the treating and quality control requirements specified in the uniform building code standards 25-12, or wood of natural resistance to decay, as defined in chapter 25 of the uniform building code.

   B.   Such retaining walls shall be engineered to resist all imposed loads.

   C.   All retaining walls exceeding thirty inches (30") in height shall have a fence, wall or guardrail at least three feet (3') above the highest adjacent ground level. In open guardrail type fencing, intermediate members shall be so placed that a sphere nine inches (9") in diameter cannot pass through. (Prior code § 86004)

   A.   Gradient And Driveway Width Adjacent To Garage Entrance: Driveways shall have a maximum gradient of twelve and one-half percent (121/2%) along the centerline of that portion of the driveway located within fifteen feet (15') of the garage entrance. The width of twenty five feet (25') of driveway adjacent to the front of the entrance shall be not less than the width of the garage opening or openings, with a minimum width of ten feet (10').

   B.   Gradient And Width Of The Remainder Of Driveway: The maximum gradient for driveways other than that portion within twenty feet (20') of the garage opening shall be twenty percent (20%) along its centerline, and shall not be less than ten feet (10') wide.

   C.   Driveway Drainage: Driveways are to drain with a minimum slope of one-half percent (1/2%) and a maximum transverse slope of five percent (5%).

   D.   Vertical Transition: Any vertical transitions shall be designed and constructed so that any portion of a vehicle having a twelve foot (12') wheelbase and a five inch (5") under vehicle clearance will not make contact with the driveway surface. (Prior code § 86005)

When it is claimed by an owner, contractor or developer of property that special circumstances or conditions applicable to the property would result in a particular hardship or unreasonable loss of enjoyment and utility of property when requirements of this chapter are strictly applied, the owner may file for a minimum exception permit in accordance with the provisions of sections 18.108.020 through 18.108.100 of this title. The application for a minor exception will be processed in accordance with sections 18.108.020 through 18.108.100 of this title. (Prior code § 86006)

This article shall apply to single lots and perimeter lots of multiple lot projects where it is necessary to provide fill materials to elevate at least thirty percent (30%) of a building pad to provide that the site drain to the street with a minimum drainage swale gradient of one percent (1%). (Prior code § 86101)

For grading lots abutting streets having a slope of one percent (1%) or less:

   A.   Such lots shall have drainage gradients not exceeding 1.25 percent, nor shall the drainage gradient be less than one percent (1%) in all areas;

   B.   The slope of the finish grades adjacent to a dwelling or structure may differ from these specified gradients if the soils engineer determines that the specified one percent (1%) to 1.25 percent gradients are not adequate for proper drainage, or, if in the opinion of the building official, steeper grades are necessary to provide drainage from the building foundations;

   C.   The lot may drain to the street at any location of the lot frontage. (Prior code § 86102)

For grading lots abutting the intersection of two (2) streets (corner lots), each street with a slope of one percent (1%) or less, such lots shall be graded according to the criteria of section 18.212.080 of this chapter. (Prior code § 86103)

For grading lots abutting streets having a slope in excess of one percent (1%), such lots shall conform with subsections 18.212.080A and B of this chapter, except that the building pad shall be no higher than is necessary to drain the lot to any location of the lower fifty percent (50%) of the frontage of the lot. (Prior code § 86104)

For grading lots abutting the intersection of two (2) streets (corner lots) with one or both streets having a slope exceeding one percent (1%), such lots shall be graded so the pad will be no higher than necessary to drain the lot to any location to the lower fifty percent (50%) of the frontage abutting the street with the steepest slope. (Prior code § 86105)

This article applies to treatment of slopes within multilot developments, and to permit boundary slopes. (Prior code § 86200)

Cut and fill slopes adjacent to property line and at other approved locations shall not be steeper than one vertical to two (2) horizontal. (Prior code § 86201)

When two (2) or more lots are graded, and cut and fill slopes of steeper than ten percent (10%) occur adjacent to the property line between the lots, the top of the slope shall be located at the property line. (Prior code § 86202)

Where earth fill of twelve inches (12") or more is placed on property having a natural average slope of five percent (5%) or less, a retaining wall not to exceed five feet (5') above the original natural grade shall be placed adjacent to the property lines at locations where a grading permit boundary line abuts vacant property, or the rear yard area of adjacent properties when the slope of the finish grade exceeds ten percent (10%) within twenty feet (20') of the permit boundary line. (Prior code § 86203(A))

Where earth fill of twelve inches (12") or more is placed on property having a natural slope of five percent (5%) or less, or is abutting a street which has a slope of five percent (5%) or less, a retaining wall not to exceed thirty inches (30") in height shall be placed adjacent to the property line when the grading permit boundary abuts a side yard of adjacent properties, excepting the rear twenty five feet (25') thereof when the fill slope exceeds ten percent (10%) in any area within the side property line. The treatment of the rear twenty five feet (25') of a lot upon a permit boundary which abuts an adjacent side yard may comply with section 18.212.150 of this chapter. (Prior code § 86204(A))

This article IV will apply to cut and fill grading for property having a natural slope steeper than five percent (5%). (Prior code § 86300)

No cut or fill slope shall exceed one vertical to two (2) horizontal. (Prior code § 86301)

No cut or fill slope shall be created which exceeds thirty feet (30') in vertical height, and any cut or fill slope which exceeds five feet (5') in height shall not exceed three hundred feet (300') in horizontal length, except slopes required for public streets may exceed three hundred feet (300') in length. (Prior code § 86302)

When two (2) or more lots are graded and cut and fill slopes exceeding ten percent (10%) occur adjacent to lot lines other than permit boundaries and streets, the top of the slope shall be located at the lot line. (Prior code § 86303)

   A.   Slopes exceeding three feet (3') in height shall be provided with irrigation systems and sufficient plants chosen from a list of erosion resisting plants available at the department of building and safety, or as approved by the Redlands park director.

   B.   Unless the final landscaping plans have been submitted, approved, and slopes planted, perennial rye or approved blade grass shall have been seeded, and the growth shall be evident prior to the final inspection of the premises. (Prior code § 86304)

   A.   Retaining walls shall not exceed six feet (6') in height, except in front yard areas where retaining walls may not exceed thirty inches (30") in height. However, retaining walls necessary for the construction of an adjacent driveway may be constructed to a maximum of six feet (6') in height at any location on the property.

   B.   Retaining walls exceeding thirty inches (30") in height will require a protective fence or guardrail of at least thirty six inches (36") in height either of solid material or with intermediate members so spaced that a nine inch (9") sphere will not pass through. The combination of a retaining wall may not exceed nine feet (9'), except if such retaining wall and guardrail is within fifteen feet (15') of an existing dwelling, the combination of retaining walls and guardrails shall not exceed six feet (6') in height. (Prior code § 86305)