Excavations shall be constructed and protected so that they do not endanger life or property.
(Ord. 1000 § 1; Code 1997 § 36-46)
The slope of cut surfaces of permanent excavations shall not be steeper than two horizontal to one vertical exclusive of terraces and exclusive of rounding 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. 1000 § 1; Code 1997 § 36-47)
Fill shall be placed in layers. The loose thickness of each layer of fill material before compaction shall not exceed 12 inches. Completed fill shall be a stable mass of well-integrated material bonded to adjacent materials and to the materials on which it rests. No organic material, such as vegetation or rubbish, or any other material not capable of proper compaction, or otherwise not conducive to stability, shall be permitted in fills. Borrowing for fill is prohibited unless approved by the city or other permitting authority. Fill shall be competent to support anticipated loads and be stable at the design slopes shown on the plans. Proper surface and subsurface drainage and other appropriate measures shall be taken to ensure the continuous integrity of fill. Earth materials shall be used which have no more than minor amounts of organic substances and have no rock or similar irreducible material with a maximum dimension greater than six inches. Larger material may be used with the approval of the department and the geotechnical engineer.
(Ord. 1000 § 1; Code 1997 § 36-48)
Fill areas shall be compacted to a maximum density as described below, and as determined by the appropriate Caltrans standard method or other alternate methods approved by the department. 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 1,000 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 1,000 square feet in slope surface but not less than one test for each 10-foot vertical increase of slope height. All tests shall be reasonably 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.
Fill that will support an engineered structure shall be compacted to a minimum of 95 percent of maximum dry density, as determined by the above tests.
Except as noted below, areas not used to support engineering structures, that will be filled to grade and revegetated or otherwise stabilized, shall be compacted to a minimum of 90 percent of maximum dry density. Prior to disturbance in the areas which have vegetation or native or imported topsoil, the top six inches of soil and organic debris, including roots, shall be excavated and stockpiled for salvage. Stripped topsoil shall be removed in a discrete layer so that subsoil spoil material is not mixed with topsoil. Stockpiled topsoil shall not be piled or compacted in a manner that significantly alters its inherent density, water holding capacity or infiltration. Topsoil shall be stockpiled to a depth not exceeding eight feet and protected from erosion. Topsoil stockpiles shall under no circumstance be compacted. Following completion of rough grading and compaction, the areas to be revegetated shall be scarified to a depth of at least six inches, and then covered with salvaged top soil. For areas where soil stabilization other than vegetation is used, soils shall be scarified to a depth of at least six inches prior to covering with alternative stabilization measures, e.g., rock mulches. Areas that are filled with the intent to enhance retention or infiltration of storm water may be compacted to less than 90 percent of maximum density, when such material is placed and compacted by a method acceptable to the department for maintaining stability and promoting infiltration.
Compaction of temporary stockpile fills, to be used for a period of not greater than six months, shall not be required, except where the department determines that compaction is necessary as a safety measure to aid in preventing saturation, sliding, or erosion of the fill. For street structural section compaction requirements, see the City of South Lake Tahoe Public Improvement and Engineering Standards, project plans, and the project special provisions where applicable.
(Ord. 1000 § 1; Code 1997 § 36-49)
The natural ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, top soil, and other unsuitable material, and where slopes are six horizontal to one vertical or steeper, by benching into competent material in a manner acceptable to the department. The keyway under the toe, if specified, shall be at least 15 feet wide.
(Ord. 1000 § 1; Code 1997 § 36-50)
The slope of permanent fills shall not be steeper than two horizontal to one vertical exclusive of terraces and exclusive of roundings described herein, unless a soils report supports a steeper slope, but shall not exceed one and one-half horizontal to one vertical unless the fill is reinforced as recommended by the geotechnical engineer. The department may require that the fill be constructed with an exposed surface flatter than two horizontal to one vertical or may require such other measures deemed necessary for stability, safety, or visual impact.
(Ord. 1000 § 1; Code 1997 § 36-51)
All grading should be kept to a minimum. Extensive regrading of a site to create building pads for construction is not recommended. Buildings shall be fitted to the land with graded areas limited, whenever possible, to the portion of the site to be covered by the structure. When graded areas cannot be covered by the structure, they shall be screened from public views by the building. Grading shall be designed to minimize the disruption to existing vegetation (including ground covers, shrubs, and trees). Revegetation of graded areas shall utilize plant materials that blend well with the surrounding vegetation, and are on TRPA's List of Approved Plant Species. (Also see TRPA Handbook of Best Management Practices.)
Where mechanical stabilization or containment of the slope by other than the use of natural material is employed, conditions of approval may require screening by vegetation. The overall shape, height and grade of any cut or fill slope shall be designed to simulate the existing natural contours and scale of the natural terrain of the site. The angle of a graded slope shall be gradually adjusted so that it merges smoothly into the angle of the natural terrain. Graded slopes shall be promptly revegetated with a ground cover or combination of ground cover, shrubs, and trees to reduce the visual impact of the graded slope and to stabilize the slope and minimize erosion. Rocks may be used to help stabilize graded slopes; however, they should be used sparingly and interspersed with trees, shrubs and ground cover. When graded slopes (either cut or fill) extend horizontally for more than 100 feet (such as along roadways), the contours shall be curved or broken to create an undulating bank with greater visual variety and a more natural appearance. The maximum height of retaining walls shall be limited to eight feet. When slopes greater than eight vertical feet must be retained, terraces shall be used to create smaller grade changes (three to five feet or less). Areas between terraces shall be wide enough to accommodate landscape planting pockets to soften the wall's appearance. Downhill sides of retaining walls shall also be planted in order to help screen the structure. Also see the TRPA Handbook of Best Management Practices. Long, straight unbroken retaining walls (greater than 100 feet) with no articulation or other surface features are not permitted.
(Ord. 1000 § 1; Code 1997 § 36-52)
Footings which 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 such building or structure is capable of withstanding the additional loads caused by such fill or surcharge. The rights of coterminous owners are as set forth in Section 832 of the Civil Code of the State of California.
(Ord. 1000 § 1; Code 1997 § 36-53)
A.
Any drainage infrastructure(s) or device(s) carrying surface water runoff required by this chapter shall be designed and constructed in accordance with standards herein, the current City of South Lake Tahoe Public Improvement Engineering Standards authorized by the director, and the standards of all other federal, regional and state agencies.
B.
Storm water management practices shall be designed, engineered, and constructed to retain storm water runoff generated on-site, within the site, and to prevent discharge of pollutants to SEZs and streets and other storm water infrastructure. Site plans incorporating principles of low impact development, green design, or enhanced infiltration of on-site and dispersed off-site flows are encouraged. Storm water management practices shall be designed to prevent degradation of quality of storm water runoff, and to maintain or decrease the quantity of storm water discharged from the site. Permanent sediment, retention, or infiltration basins shall be designed to integrate with the natural environment using such techniques as terraced sites to remove the "cut" appearance of basins, curvilinear design rather than rectangular design forms, and the use of low fencing (three feet high) with landscaping to integrate the fence with the site.
C.
Drainage infrastructure designed to convey concentrated off-site flows shall be designed, engineered, and constructed to convey these flows without causing erosion or increasing risks of downstream flooding. Modifications to existing drainage ways for concentrated off-site flows must be approved in writing by the department.
D.
When surface drainage is discharged onto any adjoining property, it shall be discharged in such a manner that it will not cause erosion or endanger any cut or fill slope or any building or structure. Grading activities that result in increased overall volume, peak flow, or the concentration of flows are only allowed if approved in writing by the department.
E.
All areas shall be graded and drained so that drainage will not cause erosion or endanger the stability of any cut or fill slope or any building or structure.
F.
Cut and fill slopes shall be provided with surface and/or subsurface drainage as necessary for stability.
(Ord. 1000 § 1; Code 1997 § 36-55)
Vehicular ways shall conform to the grading requirements of this chapter.
(Ord. 1000 § 1; Code 1997 § 36-56)
Vehicular ways shall be graded and drained in such a manner that will not allow erosion or endanger the stability of any adjacent slope. 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 must be approved by the director and any other required permitting agency.
(Ord. 1000 § 1; Code 1997 § 36-57)
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. Stabilizing soils and protecting soils and existing vegetation outside of the graded area from disturbance during and after construction prevents erosion and keeps the site from becoming a source of sediment during storms. Therefore, erosion prevention and source control shall be used, wherever possible. Where soil stabilization, erosion prevention measures, and on-site infiltration are feasible, site designs relying solely on sediment capture and storm water retention will not be approved.
B.
Grading operations shall provide erosion and sediment control measures, except upon a clear demonstration, to the satisfaction of the department, that at no stage of the work will there be any substantial risk of increased sediment discharge from the site. Temporary mulch, revegetation, or other stabilization methods shall be applied to areas where effective permanent revegetation or landscaping is not in place prior to the wet season, consistent with Chapter 5.20 SLTCC, Defensible Space. Unless otherwise exempted in this chapter, grading activity must be scheduled to ensure completion or winterization by October 15th of each year.
C.
Grading activity shall be conducted such that the smallest practicable area of erodible land is exposed at any one time during grading operations and the time of exposure is minimized. Land disturbance shall be limited to the minimum area necessary for construction.
D.
Natural features, including vegetation, terrain, watercourses and similar resources shall be protected and preserved wherever possible. Limits of grading shall be clearly defined and marked to prevent damage by construction equipment.
E.
Permanent vegetation and structural BMPs for erosion and sediment control shall be installed as soon as possible, but not later than within six months of issuance of certificate of occupancy for projects that require such a certificate. Effective temporary erosion and sediment control measures shall be installed and maintained until the permanent measures can effectively prevent erosion and control sediment.
F.
Effective installation, inspection, and maintenance of temporary and permanent erosion and sediment control structural BMPs and vegetation is required. Stockpiled soil and other construction materials shall be protected from wind or water erosion by being appropriately covered when construction is not in active progress or when required by the city. Sediment and other construction-related wastes shall be retained and properly managed on the site or properly disposed of off-site. (See Chapter 6.15 SLTCC, Article VII, Construction and Demolition Debris Recycling.)
G.
No topsoil shall be removed from the site unless otherwise directed or approved by the department. Topsoil overburden shall be stockpiled and redistributed where appropriate 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 above those which occurred before grading, except into drainage facilities whose design has been specifically approved by the department.
I.
The permittee shall ensure that vehicles do not track or spill earth materials into public streets and shall immediately remove such materials if this occurs. The site shall be cleaned and the road right-of-way swept clean as required by the city.
J.
All cut and fill slopes shall be adequately stabilized to prevent erosion and failure through temporary and permanent means.
K.
Control measures shall be employed to prevent transport of dust off the project site or into any drainage course or water body.
(Ord. 1000 § 1; Code 1997 § 36-58)
Should increased sediment discharge occur or become imminent, the permittee shall take all necessary steps to control or reduce 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 required pursuant to this chapter. The permittee shall take prompt action to resolve emergency problems; otherwise the department may institute abatement proceedings pursuant to provisions of SLTCC § 7.20.650.
(Ord. 1000 § 1; Code 1997 § 36-59)
Erosion and sediment control plans shall be designed to prevent increased discharge of sediment at all stages of grading and development from initial disturbance of the ground to project completion. The plans shall include specific measures to ensure that soil stabilization is permanent. Plans shall indicate the implementation period and the stage of construction where applicable.
For residential BMP retrofit projects, applicants may submit simplified erosion and sediment control plans that include and comply with recommendations for temporary storm water management practices made by TRPA staff, certified evaluators certified by TRPA for BMP site evaluations, or by Tahoe Resource Conservation District staff. For other small grading projects with minimal risks of erosion or sediment discharge, the director, at his or her sole discretion, may modify or waive requirements for erosion and sediment control plans listed below. Exemption from the requirement to submit or comply with any specific elements of erosion and sediment control plans listed below shall not be construed as permission to violate any other provision of this chapter.
Erosion and sediment control plans prepared pursuant to this chapter shall comply with all of the following:
A.
Except as provided in SLTCC § 7.20.100 (which requires full site winterization by October 15th), sediment and erosion control measures must be in place or be capable of being placed within 24 hours and must be in place prior to the onset of precipitation.
B.
Grading and soil disturbance shall be prohibited during the period from October 15th through May 1st unless approved in writing by the director. If the grading activity is also governed and permitted by TRPA and/or the Lahontan Regional Water Quality Control Board, written approval from the applicable permitting agency(ies) for grading from October 15th through May 1st must also be provided to the department prior to any grading from October 15th through May 1st. The director may require suspension of any and all grading activities from October 15th through May 1st without prior notice.
C.
The erosion and sediment control plan need not be a separate sheet if all facilities and measures can be shown on the grading sheets without obscuring the clarity of either the grading plan or the erosion and sediment control plan. The erosion and sediment control plan may be, but is not required to be, in the format of a storm water pollution prevention plan (as required by Lahontan Regional Water Quality Control Board for greater than one acre construction projects in the Tahoe Basin).
D.
Erosion and sediment control plans shall comply with the recommendations of the responsible civil engineer, geotechnical engineer, engineering geologist, or landscape architect involved in preparation of the grading plans. The structural and hydraulic adequacy of all storm water containment or conveyance facilities shown on the erosion and sediment control plans shall be verified by a civil engineer, and he or she shall so attest on the plans. Sufficient calculations and supporting material to demonstrate such adequacy shall accompany the plans when submitted.
E.
Except for projects solely for the purpose of installing storm water management controls for residential BMP retrofit projects, the erosion and sediment control plan for any grading project involving more than seven cubic yards or 1,000 square feet of soil disturbance shall be written, amended, and certified by a qualified professional with one of the following registrations or certifications:
1.
A California registered professional engineer;
2.
A California registered professional geologist or engineering geologist;
3.
A California registered landscape architect;
4.
A professional hydrologist registered through the American Institute of Hydrology;
5.
A certified professional in erosion and sediment control registered through EnviroCert International, Inc., or the National Institute for Certification in Engineering Technologies; or
6.
A certified professional in storm water quality registered through EnviroCert International, Inc.
F.
The applicant shall submit with the erosion and sediment control plans a detailed cost estimate covering this work.
G.
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 shall be planted by November 1st. If revegetation is infeasible or cannot be expected to stabilize the erodible area throughout the wet season additional erosion and sediment control measures including further stabilization of planted slopes may be required as appropriate to prevent increased sediment discharge.
H.
Erosion and sediment control plans shall provide for inspection and repair of all erosion and sediment control facilities by the permittee at the close of each working day if work occurs during the wet season.
I.
Erosion and sediment control plans shall identify the schedule for inspections and require permittees to document that deficiencies or repairs are completed prior to the onset of precipitation. These plans shall include specific criteria for sediment cleanout and vegetation/revegetation maintenance.
J.
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. For residential properties, these standards and specifications shall be in general compliance with the current versions of the Lake Tahoe Fire Chiefs' Living with Fire – Lake Tahoe Basin and the University of Nevada Cooperative Extension's How to Install Best Management Practices (BMPs) in the Lake Tahoe Basin, and Home Landscaping Guide for the Tahoe Basin.
(Ord. 1000 § 1; Code 1997 § 36-60)