Chapter 18.62
GRADING, EROSION, AND SEDIMENT CONTROL STANDARDS
Sections:
18.62.010 Purpose and Applicability
18.62.020 Dust Prevention and Control
18.62.030 Erosion and Sediment Control
18.62.030 Excavations and Fills
18.62.050 Grading During the Rainy Season
18.62.060 Removal of Native Vegetation
18.62.070 Revegetation and Slope Surface Stabilization
18.62.080 Protection of Watercourses
18.62.090 Setbacks for Cut and Fill Slopes
18.62.100 Storm Drainage and Runoff
18.62.010 - Purpose and Applicability
A. Purpose and applicability. This Chapter provides standards for the proper conduct of grading operations, as well as site development activities not involving grading permits. All grading operations, regardless of size, shall be conducted in a manner consistent with the requirements of this Chapter, regardless of whether a grading permit is required by Section 18.60.030 (Grading Permit Requirements).
B. Definitions. Definitions of the technical terms and phrases used in this Chapter are in Article 10 (Glossary) under “Grading.”
18.62.020 - Dust Prevention and Control
A. Applicability. To protect the health, safety, and general welfare, the permittee shall make all reasonable efforts to prevent or control blowing dust and debris from the construction site.
1. Property owners shall be responsible for maintaining their property in such a manner that dust and other wind borne debris transported to adjacent properties are kept to reasonable minimal levels.
2. In the case of site grading and other construction operations, it will also be the responsibility of the permittee to make all reasonable efforts to control blowing dust and debris onto adjacent properties.
3. When grading operations involve the hauling of dirt from one site to another, it is also the permittee’s responsibility to maintain the Public streets in a clean condition and limit any spillage which would generate dust or other blowing debris.
B. Dust prevention and control plan. A Dust Prevention and Control Plan shall be submitted in conjunction with a grading plan or other plan involving the movement of dirt. The Director of Public Works may also require the submittal of a Dust Prevention and Control Plan for other development deemed necessary.
1. Plan content. The plan shall demonstrate that the discharge of dust from the construction site will not occur, or can be controlled to an acceptable level depending on the particular site conditions and circumstances.
a. The plan shall address site conditions during construction operations, after normal working hours, and during various phases of construction.
b. The plan shall include the name and the 24 hour phone number of a responsible party in case of emergency.
c. If the importing or exporting of dirt is necessary as demonstrated by the cut and fill quantities on the grading plan, the plan shall also include the procedures necessary to keep the public streets and private properties along the haul route free of dirt, dust, and other debris.
d. When an entire project is to be graded and the subsequent construction on the site is to be completed in phases, the portion of the site not under construction shall be treated with dust preventive substance or plant materials and an irrigation system to minimize soil erosion.
e. All phased projects shall submit a plan demonstrating that dust will not be generated from future phase areas.
2. Review and use of plan. The Director of Public Works shall be responsible for the review and approval of the Dust Prevention and Control Plan. The plan shall be incorporated into the grading plan and constructive notice shall be placed on the grading plan to notify the owner and contractors of the need to comply with the Dust Prevention and Control Plan.
C. Inadequate dust prevention and control measures. In the event that inadequate dust prevention and control measures are provided by the permittee, the City may respond as follows.
1. Site investigation. If an investigation of the project site indicates that dust prevention and control measures are inadequate, the Director of Public Works may limit or halt all activities on the site until adequate dust prevention and control measures are achieved. The Director of Public Works may charge the property owner and /or contractor for reasonable costs related to providing the necessary site inspections to determine the adequacy of the dust control plan.
2. Time for compliance, enforcement. If it is determined that a property is in violation of this Section, the property owner and/or contractor will have 24 hours to bring the site into compliance. If after 24 hours, the site is not brought into compliance or an extension of time has not been granted by the Director of Public Works, the Building Official may, at any time thereafter, determine the site to be a public nuisance and serve a written notice of violation. The Director of Public Works may then enter the property for the purposes of installing, by City forces or by other means, adequate dust prevention and control measures (the cost of which shall be borne by the property owner), or the Director of Public Works may cause the owner of the site to be prosecuted as a violator of this Development Code, or the Director of Public Works may take both actions.
3. Responsibility for adequate dust prevention and control. The approval of a Dust Prevention and Control Plan does not relieve the owner or contractors of the responsibility to implement whatever additional measures may be required by the Director of Public Works to properly prevent and control dust.
D. Compliance with NPDES stormwater regulations. The Dust Prevention and Control Plan and any additional measures that may be necessary for the adequate prevention and control of dust shall comply with the NPDES Stormwater Regulations as adopted by the City and include Low Impact Development design strategies to minimize the need for soil disturbance and that maximize infiltration of stormwater runoff.
18.62.030 - Erosion and Sediment Control
Drainage improvements for site runoff, including runoff from all roadways and other impervious surfaces, shall be engineered with Low Impact Development designs to minimize the area of disturbance, maximize infiltration and minimize erosion through the appropriate use of rocked culvert inlets and outfalls, energy dissipators, check dams, cribbing, riprap, proper location of culverts that maintain native drainage networks, revegetation of exposed slopes and disturbed soils (see Section 18.62.070), and minimizing the use of artificial slopes. Bioengineered methods are encouraged. Erosion and sediment shall be controlled as provided by this Section.
A. Best management practices for projects under construction. The following Best Management Practices and Low Impact Development design principles which address the problem of urban runoff shall apply to all development and proposed land uses. The following requirements shall apply at the time of demolition of an existing structure or commencement of construction and until receipt of a Certificate of Occupancy.
1. Minimize Runoff and Pollution from Construction. All development shall minimize construction site runoff and erosion, and eliminate the discharge of sediment and other stormwater pollution resulting from construction activities (e.g., chemicals, vehicle fluids, concrete truck wash-out, and litter), to the extent feasible, through implementation of Best Management Practices and low impact development design principles. Sediment and construction waste from construction sites and parking areas shall not leave the site.
2. Slope surface stabilization. Temporary mulching, seeding or other suitable stabilization measures approved by the Director of Public Works shall be used to protect exposed erodible areas during construction. Earth or paved interceptors and diversions shall be installed at the top of cut or fill slopes where there is a potential for erosive surface runoff.
3. Use of plastic covering. On an emergency basis only, plastic covering may be utilized to prevent erosion of an otherwise unprotected area, along with runoff devices to intercept and safely convey the runoff.
4. Placement of excavated soil. Excavated soil shall be located on the site in a manner that eliminates the possibility of sediments running into the street, adjoining properties, and/or storm drain facilities and waterways. Soil piles shall be covered and contained until the soil is either used or removed.
5. Removal of off-site sediments. Any sediments or other materials which are tracked off the site shall be removed the same day as they are tracked off the site. Where determined necessary by the Director of Public Works, a temporary sediment barrier shall be installed. Removal shall be by scraping, collecting, and properly disposing of debris. Street washing is prohibited unless performed in the presence of a City Inspector.
6. Prohibition against washing construction vehicles. No washing of construction or other industrial vehicles shall be allowed adjacent to a construction site. No runoff from washing vehicles on the construction site shall be allowed to leave the site.
7. Erosion control devices. In order to prevent polluting sediment discharges, erosion and sediment control devices shall be installed as required by the Director of Public Works for all grading and filling. Control devices and measures that may be required include, but are not limited to energy absorbing structures or devices to reduce the velocity of runoff water, sand bags, straw bales, straw wattles, detention ponds, sediment ponds, or infiltration pits, or down drains, chutes or flumes.
8. Minimize Land Disturbance During Construction. Land disturbance activities during construction (e.g., clearing, grading, and cut-and-fill) shall be minimized, to the extent feasible, to avoid increased erosion and sedimentation. Soil compaction due to construction activities shall be minimized, to the extent feasible, to retain the natural stormwater infiltration capacity of the soil.
9. Minimize Disturbance of Natural Vegetation. Construction shall minimize the disturbance of natural vegetation (including significant trees, native vegetation, and root structures), which are important for preventing erosion and sedimentation.
B. Final erosion control measures. Within 30 days after completion of grading, and no later than November 1, all surfaces disturbed by vegetation removal, grading, haul roads, or other construction activity that alters natural vegetative cover, shall be revegetated to control erosion as provided by Section 18.62.070 (Revegetation and Slope Surface Stabilization) unless covered with impervious or other improved surfaces authorized by approved plans. Erosion controls may include any combination of mechanical, chemical, or vegetative measures, including those described in USDA Soil Conservation Service Bulletin 347.
18.62.040 - Excavations and Fills
A. General standards. All excavations and fills shall be designed and constructed in compliance with the following standards.
1. Area of cuts and fills. Cuts and fills shall be limited to the minimum amount necessary to provide stable embankments for required parking areas or street rights-of-way, structural foundations, and adequate residential yard area or outdoor storage or sales area incidental to a non-residential use.
2. Retention of natural features. Grading operations shall be designed and conducted to maximize retention of natural land forms and features (e.g., rolling hills, ridgetops, areas of extensive vegetation, watercourses, etc.).
3. Final contours. Contours, elevations and shapes of finished surfaces shall be blended with adjacent natural terrain to achieve a consistent grade and natural appearance.
a. Borders of cut slopes and fills shall be rounded off to a minimum radius of five feet to blend with the natural terrain. Large flat planes or sharp angles at intersections with natural terrain shall be prohibited.
b. Manufactured slopes in excess of five feet in height and/or 200 feet in length, shall be landform graded, with a variety of slope ratios applied to the cut or fill slopes.
c. For individually developed lots, all cut or fill slopes shall be landform graded when a building pad area is more than 4,500 square feet, or when the total graded area of the lot is more than 9,000 square feet. The maximum allowed slope shall be determined for cuts and fills by Subsections B. and C. of this Section.
4. Archeological resources. In the event archeological resources are unearthed or discovered during any construction activities, construction activities shall cease, the Department shall be notified, and the proper disposition of resources shall be accomplished as required by Section 18.50.030 (Archaeological Resource Preservation).
B. Standards for excavations. Cuts shall be designed and constructed consistent with the following provisions, except where approved soils engineering and/or engineering geology reports recommend other standards, and except where the Director of Public Works waives these standards for minor cuts not intended to support structures.
1. Slope. The slope of permanent cut surfaces shall be no steeper than is safe for the intended use, but in no event more than two feet horizontal to one vertical.
2. Drainage and terracing. Drainage and terracing of cuts shall be provided as required by Subsection D.
C. Standards for fills. Fills shall be designed and constructed consistent with the following provisions, except where an approved soils engineering report recommends other standards, and except where the Director of Public Works waives these standards for minor fills not intended to support structures.
1. Fill location. Fill slopes shall not be constructed on natural slopes steeper than two feet horizontal to one foot vertical.
2. Preparation of ground. The ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, topsoil and other unsuitable materials, scarifying to provide a bond with the new fill, and where slopes are steeper than five to one and the height is greater than five feet, by benching into sound bedrock or other competent material as determined by a soils engineer. The bench under the toe of a fill slope steeper than five to one shall be at least 10 feet wide. The area beyond the toe of fill shall be sloped for sheet overflow or a paved drain shall be provided. When fill is to be placed over a cut, the bench under the toe of fill shall be at least 10 feet wide but the cut shall be made before placing the fill and acceptance by the soils engineer or engineering geologist or both as a suitable foundation for fill.
3. Fill material. Detrimental amounts of organic material shall not be permitted in fills. No rock or similar irreducible material with a maximum dimension greater than 12 inches shall be buried or placed in fills, except where the Director of Public Works allows the placement of larger rock when the soils engineer devises a proper method of placement, continuously inspects its placement, and approves fill stability, subject also to the following requirements:
a. Potential rock disposal areas shall be shown on the grading plan.
b. Rock sizes greater than 12 inches in maximum dimension shall be placed 10 feet or more below grade, measured vertically.
c. Rocks shall be placed so as to ensure filling all voids with fines.
4. Fill placement. 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.
5. Depth of fill. The depth of fill from the substructure to finished grade across a building pad shall not exceed that specifically recommended by the geotechnical engineer.
6. Compaction. All fills shall be compacted to a minimum of 90 percent of maximum density in compliance with the Uniform Building Code, or as determined by a soils or geotechnical engineer. In-place density shall be determined in compliance with the Uniform Building Code.
7. Slope. The slope of permanent fill surfaces shall be no steeper than is safe for the intended use, but in no event more than two feet horizontal to one vertical.
8. Drainage and terracing. Drainage and terracing of fills shall be provided as required by Subsection D. of this Section.
D. Drainage and terracing of cuts and fills. Proper drainage and terracing of cuts and fills shall be constructed as follows, to ensure the continuing integrity of fills. The following requirements apply only to cuts and fills with surface slopes steeper than three feet horizontal to one vertical, except where otherwise required on approved grading plans by the Director of Public Works. Additional standards applicable to the provision of storm drainage facilities as part of grading projects are established by Section 18.62.100 (Storm Drainage and Runoff).
1. Terraces. Terraces at least six feet in width shall be established at not more than 30-foot vertical intervals on all cut or fill slopes to control surface drainage and debris, except that where only one terrace is required, it shall be at mid-height.
a. For all cut or fill slopes greater than 60 feet and up to 120 feet in vertical height, one terrace at approximately mid-height shall be 12 feet in width. Terrace widths and spacing for cut and fill slopes greater than 120 feet in height shall be designed by the civil engineer and approved by the Director of Public Works. Suitable access shall be provided to permit proper cleaning and maintenance.
b. Swales or ditches on terraces shall:
(1) Have a minimum gradient of five percent;
(2) Be paved with reinforced concrete not less than three inches in thickness or an approved equal paving; and
(3) Have a minimum depth at the deepest point of one foot and a minimum paved width of five feet.
c. A single run of swale or ditch shall not collect runoff from a tributary area exceeding 13,500 square feet (projected) without discharging into a down drain.
2. Subsurface drainage. Cut and fill slopes shall be provided with subsurface drainage as necessary for stability.
3. Disposal. All drainage facilities shall be designed to carry waters to the nearest practicable drainage way approved by the Director of Public Works and/or other appropriate jurisdiction as a safe place to deposit the waters with areas designated for infiltration, such as: vegetated swales, water gardens, and curb cuts. Erosion of ground in the area of discharge shall be prevented by installation of nonerosive down drains or other approved devices.
4. Building pad drainage. Building pads shall have a drainage gradient of two percent toward approved drainage facilities but should include runoff interception facilities like vegetated swales and water gardens, where feasible, that encourage infiltration over runoff.
5. Interceptor drains. Paved interceptor drains shall be installed along the top of all cut slopes where the tributary drainage area above slopes towards the cut and has a drainage path greater than 40 feet measured horizontally. Interceptor drains shall be paved with a minimum of three inches of concrete or gunite and reinforced. They shall have a minimum depth of 12 inches and a minimum paved width of 30 inches measured horizontally across the drain. The slope of the drain shall be approved by the Director of Public Works.
6. Drainage facility design. The use of Low Impact Development drainage facility design is encouraged and information resources are available to the public (see LID and Stormwater Resources). Runoff from roofs, parking lots, etc. is best minimized and then the lessened runoff is infiltrated into permeable areas within the native landscape on site to maximize recharge of groundwater resources and to minimize pollution of native waterways with excessive stormwater runoff. Design plans including vegetated swales, permeable building materials (wood decking, permeable pavement, pavers, etc.), rain gardens, green roofs, and curb cuts that convey runoff to permeable soil areas are encouraged. Non-undergrounded drainage facilities shall be designed with integral color (e.g., muted earth tones, etc.) and materials (e.g., rock, landscaping, etc.) to minimize visibility. Down drains on highly visible slopes shall be installed underground where feasible.
E. Protection of adjacent property. 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 Section 832 of the California Civil Code.
18.62.050 - Grading During the Rainy Season
Grading may only be permitted during the period from November 1 through March 30 if the Director of Public Works determines that soil conditions at the site are suitable, and adequate and effective erosion and sediment control measures will be in place during all grading operations.
18.62.060 - Removal of Native Vegetation
Grading shall be designed and grading operations shall be conducted to minimize the removal or disturbance of native vegetation to the maximum extent feasible.
A. Trees not approved for removal in the grading permit shall be protected from damage by proper grading techniques, and by fencing, and conducting no grading or heavy equipment operations within the protected zone of the tree.
B. The limits of grading shall be clearly defined and marked to prevent damage to native vegetation by grading or construction equipment.
C. All trees to be removed and retained, and all markings and protective devices shall be inspected and approved by the Department prior to the commencement of grading operations.
18.62.070 - Revegetation and Slope Surface Stabilization
Where natural vegetation has been removed through grading in areas that are not to be occupied by structures, the areas shall be replanted in compliance with the approved revegetation plan and this Section to prevent erosion after construction is completed.
A. Preparation for revegetation. Topsoil removed from the surface in preparation for grading and construction shall be stored on or near the site and protected from erosion while grading operations are underway, provided that topsoil storage shall not be located where it would cause suffocation of root systems of trees intended to be preserved. After completion of grading, topsoil shall be restored to exposed cut and fill embankments or areas around building pads to provide a suitable base for seeding and planting.
B. Methods of revegetation. Acceptable methods of revegetation include broadcast, hydro-seeding, or the planting of native plant materials with equivalent germination rates. Where lawn or turf grass is to be established, lawn grass seed or other appropriate landscape cover shall be sown at not less than four pounds to each 1,000 square feet of land area. Other revegetation methods offering equivalent protection may be approved by the Director of Public Works. Plant materials shall be watered at intervals sufficient to ensure survival and growth. The use of drought tolerant, fire resistive native plant materials is encouraged.
C. Timing of revegetation measures. Revegetation for the purpose of erosion and sediment control (Section 18.62.030) shall be installed within 30 days after completion of grading on all surfaces disturbed by vegetation removal, grading, haul roads, or other construction activity that alters natural vegetative cover. Other permanent revegetation or landscaping should begin on the construction site as soon as practical and shall begin no later than six months after achieving final grades and utility emplacements. All revegetation shall occur prior to October 15, or as soon thereafter as practical and, in all cases, before November 1, to provide sufficient time for seed germination prior to the rainy season.
18.62.080 - Protection of Watercourses
Grading, dredging or diking shall not alter any intermittent, ephemeral, or perennial stream, or natural body of water, except as permitted through approval of a grading permit in compliance with this Article, any planning permits required by this Development Code, and any necessary permits from the California Department of Fish and Game, Army Corps of Engineers, and Regional Water Quality Control Board (for example, a Section 1601-1603 permit from the Department of Fish and Game, a Section 404 permit from the Army Corps, and/or a Notice of Intent and Waste Discharge Permit from the Water Quality Control Board, etc.).
A. Protection standards. Grading operations within, adjacent to or involving the alteration of watercourses shall be conducted as follows:
1. The flood carrying capacity of any altered or relocated portion of a watercourse shall be maintained.
2. Watercourses shall not be obstructed unless an alternate drainage facility is approved.
3. Fills shall not be placed within watercourses.
4. Grading equipment shall not cross or disturb channels containing live streams without appropriate permits from State Department of Fish and Game and other relevant resources agencies.
5. Excavated materials shall not be deposited or stored in or adjacent to a watercourse where the materials can be washed away by high water or storm runoff.
B. Required agency notification. Where the alteration of a watercourse is proposed or allowed within an area determined by the Director of Public Works to be subject to flooding, any responsible agency shall be notified prior to any alteration or relocation of a watercourse, and evidence of the notification shall be submitted to the Federal Insurance Administration.
18.62.090 - Setbacks for Cut and Fill Slopes
Cut and fill slopes shall be set back from property lines as provided by this Section. The required setback dimensions shall be as shown in Figure 6-1.
A. Top of cut slope. Except where otherwise provided by this Section, the top of cut slopes shall be set back from adjacent property lines a distance of at least one-fifth of the vertical height of the cut, with a minimum of two feet and a maximum of 10 feet. Greater distances may be required to accommodate any necessary interceptor drains.
B. Toe of fill slope. Except where otherwise provided by this Section, the toe of a fill slope shall be set back from adjacent property lines a distance of at least one-half the height of the slope, with a minimum of two feet and a maximum of 10 feet. Where a fill slope is to be located near a property line and the adjacent property is developed, the Director of Public Works may require additional precautions to protect the adjacent property from damage as a result of grading. The precautions may include the measures specified in Section 18.62.040.E. (Protection of adjacent property), additional setbacks, provisions for retaining or slough walls, mechanical or chemical treatment of the fill slope surface to minimize erosion, or additional provisions for the control of surface waters.
C. Setback exceptions. The Director of Public Works may approve alternatives to the setbacks required by Subsections A. and B. above, based on investigations and recommendations from a qualified engineer or engineering geologist.
D. Buffers from watercourses and environmentally sensitive habitats. No grading shall be allowed within 100 feet of any area determined by the Director of Public Works to be an environmentally sensitive habitat area, or from the top of the bank of a watercourse as determined by the Director of Public Works, unless the grading is approved as a discretionary project in compliance with Section 18.60.050.A.2, and is subject to environmental review in compliance with Section 18.60.040.B.
Figure 6-1 - Grading Setback Requirements
18.62.100 - Storm Drainage and Runoff
A. Design and construction. Drainage systems and facilities proposed within existing or future public rights-of-way shall be designed and constructed in compliance with Section 18.88.050 (Subdivision Improvement Requirements). The design and construction of drainage facilities required for cuts and fills are subject to Section 18.62.040.D. above. Other drainage systems and facilities shall be designed in compliance with good engineering practices that incorporate Low Impact Development design techniques to infiltrate direct precipitation and runoff to minimize pollutive runoff entering storm drains wherever possible.
B. Natural drainage systems. Proposed grading projects shall include Low Impact Development design provisions to retain natural drainage patterns and preserve the infiltration, purification, detention, and retention functions of natural drainage systems that exist on the site, where appropriate and feasible.
C. Minimize Runoff. Proposed grading projects shall include Low Impact Development design provisions to minimize increases in stormwater runoff volume and peak runoff rate, to the extent feasible. In developing a Runoff Mitigation Plan, an applicant shall demonstrate an effort to reduce projected runoff for the project by 20 percent from the base 1985 10-year storm.
D. Minimize Erosion. Long-term drainage improvements for site runoff, including runoff from all roadways and other impervious surfaces, shall be designed to minimize erosion through the appropriate use of rocked culvert inlets and outfalls, energy dissipaters, check dams, cribbing, riprap, proper location of culverts, re-vegetation of exposed slopes (see Section 18.62.070), and minimizing the use of artificial slopes. LID methods are encouraged.
F. Areas subject to flooding. Grading or structures are not permitted in an area determined by the Director of Public Works to be subject to flood hazard by reason of inundation, overflow, high velocity or erosion, except where the grading or structures are in conformity with the standards of Section 18.62.030 (Erosion and Sediment Control) and the following provisions.
1. Hazard elimination. The grading and/or structures shall be designed and constructed to incorporate provisions to eliminate identified hazards to the satisfaction of the Director of Public Works. These provisions may include providing adequate drainage facilities, protective walls, suitable fill, raising the floor level of buildings, or by other means. In the application of this standard the City shall enforce as a minimum the current Federal flood plain management regulations as defined in the National Flood Insurance Program authorized by United States Code Sections 4001-4128 and contained in Title 44 Code of Federal Regulations, Part 59 et seq., which are hereby adopted and incorporated into this Chapter by reference as though they were fully set forth here.
2. Letter of Map Revision (LOMR). Where the Director of Public Works approves grading and/or structures within an area subject to flooding on the basis of proposed protective measures to eliminate flooding hazards, the applicant shall file a Letter of Map Revision (LOMR) for the applicable Flood Insurance Rate Map (FIRM) with the Federal Emergency Management Agency (FEMA) prior to the issuance of a Certificate of Occupancy or the approval of a final building inspection by the City.