Loomis Municipal Code Art. VII Design Standards

Excavations shall be constructed or protected so that they do not endanger life or property.

(Ord. 55 § 1.43, 1987)

The slope of cut surfaces of permanent excavations shall not be steeper than two horizontal to one vertical exclusive of terraces and exclusive of roundings described herein. Steeper slopes will be permitted in competent bedrock provided such slope inclinations are in accordance with recommendations contained in the geotechnical or geological report. The bedding planes or principal joint sets in any formation when dipping towards the cut face shall not be daylighted by the cut slope unless the soils and geologic investigations contain recommendations for steeper cut slopes. Cut slopes shall be rounded into the existing terrain to produce a contoured transition from cut face to natural ground.

(Ord. 55 § 1.44, 1987)

Fills shall be constructed in layers. The loose thickness of each layer of fill material before compaction shall not exceed eight inches. Completed fills shall be stable masses of well-integrated material bonded to adjacent materials and to the materials on which they rest. Fills shall be competent to support anticipated loads and be stable at the design slopes shown on the plans. Proper drainage and other appropriate measures shall be taken to ensure the continuing integrity of fills. Earth materials shall be used which have no more than minor amounts of organic substance and have no rock or similar irreducible material with a maximum dimension greater than twelve inches.

(Ord. 55 § 1.45, 1987)

All fills shall be compacted throughout their full extent to a minimum of ninety percent of maximum density as determined by appropriate ASTM standard method or other alternate methods approved by the director of public works. Tests to determine the density of compacted fills shall be made on the basis of not less than one test for each two-foot vertical lift of the fill but not less than one test for each one thousand cubic yards of material placed. Additional density tests at a point approximately one foot below the fill slope surface shall be made on the basis of not less than one test for each one thousand square feet in slope surface but not less than one test for each ten-foot vertical increase of slope height. All tests shall be reasonable uniformly distributed within the fill or fill slope surface. Results of such testing and location of tests shall be presented in the periodic and final reports. Compaction may be less than ninety percent of maximum density, as determined by the above test, within three inches of the slope surface when such surface material is placed and compacted by a method acceptable to the director of public works for the planting of the slopes. Compaction of temporary storage fills, to be used for a period of not greater than six months, shall not be required, except where the director of public works determines that compaction is necessary as a safety measure to aid in preventing saturation, sliding, or erosion of the fill.

(Ord. 55 § 1.46, 1987)

The natural ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, top soil, and other unsuitable material, scarifying the resulting top six inches, and where existing slopes are five horizontal to one vertical or steeper, by benching into competent material in a manner acceptable to the director of public works. The keyway under the toe, if specified, shall be at least ten feet wide.

(Ord. 55 § 1.47, 1987)

The slope of permanent fills shall not be steeper than two horizontal to one vertical exclusive of terraces and exclusive of roundings described herein. The director of public works may require that the fill be constructed with an exposed surface flatter than two horizontal to one vertical or may require such other measures as he deems necessary for stability and safety.

(Ord. 55 § 1.48, 1987)

Footings which may be affected by an 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 such building or structure is capable of withstanding the additional loads caused by such fill or surcharge. The rights of coterminous owners shall be as set forth in Section 832 of the Civil Code of the state of California.

(Ord. 55 § 1.49, 1987)

Unless otherwise recommended in a soil and geologic investigation report, Figures 70-1 and 70-2 on page 763 of the 1985 Uniform Building Code or said similar provisions as provided for in adopted successor codes shall be used for establishing setbacks for property boundaries, buildings and structures other than fences and retaining walls.

(Ord. 55 § 1.50, 1987)

A. Rolling Terrain Grading. Grading of rolling terrain shall be accomplished in a manner whereby the effect of the rolling terrain is maintained as close to that which exists, to the extent practicable. Every effort shall be made to keep grading of rolling terrain to a minimum.

B. Boundary Grading. Special attention shall be given to grading adjacent to the exterior perimeter property line of a development. All adverse effects to off-site properties adjacent to new developments shall be kept to a minimum. Fills and cuts adjacent to the exterior perimeter property line shall be designed in accordance with the following:

1. When grading along existing residential property, the grade should be, if at all possible, held equal to or lower than the existing property grades. When grades are to be raised higher than existing adjacent residential lots, a masonry retaining wall shall be used, regardless of the difference in elevation. Existing drainage ways shall be maintained unless approved otherwise by director of public works. The wall shall be located as close to the property line as is feasible for construction. If permission can be obtained from the adjacent property owner(s), the wall should be placed on the property line or onto the upper lot and the fence relocated to the top of the wall. Permission must also be obtained of neighbor to enter the property for construction purposes.

2. If possible, all exterior slopes, fill or cut, shall be constructed off-site, with the property line being situated a minimum of two feet inside the higher elevation. If a right of entry cannot be obtained for this, a retaining wall shall be placed as near to property line as practicable.

3. A right of entry shall be required for all off-site fills and grading prior to plan approval. (See Form GR-1).

4. Maximum slope shall be 2:1 or as specified by the geotechnical engineer.

5. All slopes steeper than 4:1 adjacent to the public right-of-way and private streets shall be protected with permanent erosion control measures.

6. All fill material shall achieve ninety percent relative compaction certified by a registered geotechnical engineer.

7. When a drainage swale or ditch is proposed to run adjacent to the property line, a level area, minimum width of five feet, is required between the property line and the top of the slope bank.

8. A specific off project haul route shall be approved by the director of public works when over seven hundred fifty cubic yards of imported or exported soil is required. Where a haul route has not been determined at the time of plan approval, the permit shall be conditioned stating that no grading activities shall occur until a haul route has been approved by the town engineer.

C. Interior Grading. Differences in elevations across interior property lines within a development, such that slopes or retaining walls are required, shall conform to the following:

1. Cross lot drainage is not allowed unless specifically approved by the director of public works for tree preservation. All single-family residential lots shall have Class 1 grading as per the Loomis Standard Details unless approved otherwise by the director of public works. When a Class 2 or Class 3 lot grading plan is proposed as part of a tentative map application for a single-family residential subdivision, the tentative grading plan showing rear lot drains shall be supplemented with an alternative plan showing the effect on the subdivision if rear lot drains are not utilized.

2. Retaining walls shall be required whenever adjacent side lot elevations differ by more than one half-foot. In such cases, a minimum three-foot wide walk path shall be maintained adjacent to all side property lines. Where the design engineer feels that this path will be maintained without the use of a retaining wall, application for a waiver may be made by preparing and submitting a standard sideyard setback guarantee. The sideyard setback guarantee shall specify the lots for which a waiver of the retaining wall requirement is requested, the minimum setback of the proposed structure from the property line, and shall state that should the minimum setback not be possible during construction, a retaining wall shall be constructed to requirements of this chapter. Upon approval, a copy of these will be given to the building division and planning department to utilize in their review. Any deviation to these setbacks will be subject to approval by the public works and planning department.

3. Property lines shall be situated a minimum of one foot inside the top of fill or cut slopes when pad elevations differ by one half-foot or less. When retaining walls are used, the property lines shall be situated on the high side of the retaining wall with a minimum setback of one foot from the property line to the retaining wall. Where pad elevations differ by more than one half foot and waiver of placement of retaining walls is requested per the requirements stated above, property lines shall be situated a minimum of two feet inside the top of fill or cut slopes.

4. The maximum earth slopes allowed shall be 2:1 (horizontal to vertical). Minimum asphalt concrete surface slopes shall be one percent and minimum concrete cement surface slopes shall be 0.4 percent. All proposed slopes that are 3:1 or steeper shall be shown on the plans by some type of slope symbol delineation.

5. Lots on the low side of streets at sag points shall have pad elevations a minimum of one foot above the one hundred-year water surface elevation assuming failure of all subsurface drainage systems.

D. Retaining Walls. Retaining walls, when required, shall be shown on the plans and shall include all necessary information and details for construction. All retaining walls adjacent to the public right-of-way or along the exterior boundary of the project shall be masonry. Other retaining walls less than or equal to two feet six inches in height may be pressure-treated redwood conforming to the Loomis Standard Details. Walls higher than two feet six inches shall be masonry. All walls higher than four feet as measured from base of foundation to top of wall shall be substantiated with structural calculations stamped by a registered civil or structural engineer and a building permit shall be obtained from the building division prior to engineering approving the plans which reflect installation of the retaining walls.

E. Grading near Trees. Grading near trees shall follow the requirements of the zoning ordinance.

(Ord. 210 § 19, 2004)

The drainage structures and devices required by this chapter shall be designed and constructed in accordance with standards herein and criteria authorized by the director of public works.

(Ord. 55 § 1.51, 1987)

All drainage facilities shall be designed to carry surface and subsurface waters to the nearest adequate street, storm drain, natural watercourse or other juncture, and shall be subject to the approval of the director of public works. Drainage areas shall conform to patterns established by the director of public works.

(Ord. 55 § 1.52, 1987)

All areas shall be graded and drained so that water will not pond or accumulate. Drainage shall be effected in such a manner that it will not cause erosion or endanger the stability of any cut or fill slope or any building or structure.

(Ord. 55 § 1.53, 1987)

Cross lot drainage is not allowed unless specifically approved by the director of public works for tree preservation or severe disruption to the existing ground elevation and surrounding area. All residential, commercial or industrial lots shall provide front lot drainage, unless approved otherwise by the director of public works.

(Ord. 55 § 1.54, 1987; Ord. 210 § 20, 2004)

Terraces at least eight feet in width shall be established at not more than twenty-five feet in height intervals for all cut and fill slopes exceeding thirty feet in height. Where only one terrace is required, it shall be at approximately midheight. Suitable access shall be provided to permit cleaning and maintenance of terraces and terrace drains. Swales or ditches on terraces shall have a minimum depth of one foot, a minimum longitudinal grade of four percent, a maximum longitudinal grade of twelve percent. Downdrains or drainage outlets shall be provided at approximately three hundred foot intervals along the drainage terrace. Downdrains and drainage outlets shall be of approved materials and of adequate capacity to convey the intercepted waters to the point of disposal. If the drainage discharges onto natural ground, adequate erosion protection shall be provided.

(Ord. 55 § 1.55, 1987)

Cut and fill slopes shall be provided with surface and/or subsurface drainage as necessary for slope stability and control groundwater seepage.

(Ord. 55 § 1.56, 1987)

The following shall apply to the control of erosion and sediment from grading operations:

A. Grading plans shall be designed with long term erosion and sediment control as a primary consideration.

B. Grading operations during the rainy season shall provide erosion and sediment control measures except upon a clear demonstration, to the satisfaction of the director of public works, that at no stage of the work will there be any substantial risk of sediment discharge from the site.

C. Should grading be permitted during the rainy season, the smallest practicable area of erodible land shall be exposed at any one time during grading operations and the time of exposure shall be minimized.

D. Natural features, including vegetation, terrain, watercourses and similar resources shall be preserved wherever possible. Limits of grading shall be clearly defined and marked to prevent damage by construction equipment.

E. Permanent vegetation and structures for erosion and sediment control shall be installed as soon as possible.

F. Adequate provision shall be made for long term maintenance of permanent erosion and sediment control structures and vegetation.

G. No topsoil shall be removed from the site unless otherwise approved by the director of public works. Topsoil overburden shall be stockpiled and redistributed within the graded area after rough grading to provide a suitable base for seeding and planting. Runoff from the stockpiled area shall be controlled to prevent erosion and resultant sedimentation of receiving water.

H. Runoff shall not be discharged from the site in quantities or at velocities substantially above those which occurred before grading except into drainage facilities whose design has been specifically approved by the director of public works.

I. Permittee shall take precautions to ensure that vehicles do not track or spill earth materials into public streets and shall immediately remove such materials if this occurs.

(Ord. 55 § 1.57, 1987)

Should sediment discharge occur or become imminent, permittee shall take all necessary steps to control such discharge. Such steps may include construction of additional facilities or removal or alteration of facilities required by approved erosion and sediment control plans. Facilities removed or altered shall be restored as soon as possible afterward or appropriate changes in the plan shall be immediately requested pursuant to this chapter. Permittee shall take prompt action to resolve emergency problems; otherwise the director of public works may institute abatement proceedings pursuant to the provisions of Section 12.04.640.

(Ord. 55 § 1.58, 1987)

Erosion and sediment control plans prepared pursuant to this chapter shall comply with the town's stormwater management plan, the California Stormwater Quality Association Stormwater Best Management Practice Handbooks, adhere to and obtain the required state and federal regulations and permits, and all of the following:

A. An erosion and sediment control plan shall be required whenever:

1. The graded portion of the site includes more than ten thousand square feet of area having a slope greater than ten percent;

2. There is significant risk that more than two thousand five hundred square feet will be unprotected or inadequately protected from erosion during any portion of the rainy season;

3. Grading will occur within seventy-five feet of the center of any watercourse; or

4. The director of public works determines that the grading will or may pose a significant erosion or sediment discharge hazard for any reason.

B. The applicant shall submit, with his erosion and sediment control plans, a detailed cost estimate covering this work.

C. Erosion and sediment control plans shall include an effective revegetation program to stabilize all disturbed areas which will not be otherwise protected. All such areas where grading has been completed between May 1st and October 1st shall be planted by November 1st. Graded areas completed at other times of the year shall be planted within fifteen days. If revegetation is not feasible or cannot be expected to stabilize an erodible area with assurance during any part of the rainy season and the unstable area exceeds two thousand five hundred square feet, additional erosion and sediment control measures or irrigation of planted slopes may be required as appropriate to prevent increased sediment discharge.

The following is a list of general notes that shall be placed on sedimentation and erosion control plans as erosion and sedimentation control measures.

1. All erosion and sediment control measures shall be implemented by October 1st or as approved by the town engineer and specified on the grading plans.

2. Straw bales shall be stockpiled on site at a rate of 1.5 bales per acre by September 25th. Measures shall be provided to keep straw dry.

3. All slopes greater than 10:1 shall be covered with broadcast straw at a rate of fifty bales or four thousand pounds per acre. For slopes 4:1 or steeper, straw shall be pressed in place. Other methods are subject to approval of the town engineer.

4. Slopes steeper than 4:1 and adjacent to town right-of-way, flood plains, natural drainages, parkland or designated open space shall be hydroseeded.

5. All bare areas, regardless of slope, within fifty feet of natural drainages shall be covered with straw and pressed in place.

6. Where required, broadcast seed shall be applied at a minimum as follows:

7. No grading or trenching, except as required for erosion or sediment control, shall occur within thirty-five feet from the centerline of perennial and intermittent drainage swales between October 1st and May 1st except as approved by the department of fish and game.

8. All erosion and sediment control measures shall be checked following all storms to ensure that all measures are functioning properly.

9. Sediment and trash accumulated in drainages or detention basins shall be removed as soon as possible. In addition, oil and material floating on water surface must be skimmed weekly and the debris properly disposed of.

10. Construction activities occurring between October 1st and May 1st shall have erosion and sediment control measures in place or capable of being placed within twenty-four hours. The contractor shall ensure that the construction site is prepared prior to the onset of any storm.

11. The contractor shall establish a specific site within the development for maintenance and storage of equipment or any other activity that may adversely contribute to the water quality of the runoff. This area shall have a berm located around its perimeter. This area shall be restored to acceptable condition upon completion of project.

12. Hydroseeding may be considered as an alternative to broadcast straw subject to the public works department based on a review of the existing site conditions (location, slopes, proximity to streams) and time of year.

D. Erosion and sediment control plans shall be designed to prevent discharge of sediment at all stages of grading and development from initial disturbance of the ground to project completion. Every feasible effort shall be made to ensure that site stabilization is permanent. Plans shall indicate the implementation period and the stage of construction where applicable.

E. Erosion and sediment control plans shall comply with the recommendations of any civil engineer, geotechnical engineer, engineering geologist, or landscape architect involved in preparation of the grading plans.

F. The structural and hydraulic adequacy of all stormwater containment or conveyance facilities shown on the erosion and sediment control plans shall be verified by a civil engineer, and he shall so attest on the plans. Sufficient calculations and supporting material to demonstrate such adequacy shall accompany the plans when submitted.

G. Erosion and sediment control plans shall be designed to meet anticipated field conditions.

H. Erosion and sediment control plans shall provide for inspection and repair of all erosion and sediment control facilities at the close of each working day during the rainy season and for specific sediment cleanout and vegetation maintenance criteria.

I. Erosion and sediment control plans shall comply with any and all standards and specifications adopted herein for the control of erosion and sedimentation on grading sites.

J. Mitigation Monitoring Requirement. All mitigation measures and mitigation monitoring measures as required to mitigate environmental impacts shall be complied with. The developer is responsible for monitoring all mitigation measures and shall submit to the planning and public works department a letter certifying compliance with such measures prior to beginning any construction. For projects over one acre, a copy of the storm water pollution prevention plan shall be available at the project site.

(Ord. 55 § 1.59, 1987; Ord. 210 § 21, 2004)

Vehicular ways shall conform to the grading requirements of this chapter.

(Ord. 55 § 1.60, 1987)

Vehicular ways shall be graded and drained in such a manner that will not allow erosion or endanger the stability of any adjacent slope. Grading shall not adversely affect the flow and surface water. Surface discharge onto adjoining property shall be controlled in such a manner that it does not cause erosion or endanger existing improvements. Bridges and culverts installed in watercourses shall be approved by the Placer County flood control and water conservation district.

(Ord. 55 § 1.61, 1987)

Dust control shall follow the latest version of the Fugitive Dust Control Measures (Rule 228) provided by the Placer County air pollution control district.

(Ord. 210 § 22, 2004)