Calabasas Municipal Code Ch. 15.11 Grading, Erosion and Sediment Control Standards

This chapter provides standards for the proper conduct of grading operations and design standards for excavations and fills as well as site development activities not involving grading permits. All grading operations shall be conducted in a manner consistent with the requirements of this chapter, regardless of whether a grading permit is required by Section 15.10.030.

(Ord. No. 2010-268, § 1, 1-27-2010)

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 building pad and 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 nonresidential use.

2. Grading on Hillsides. Hillside grading shall comply with the grading provisions of the Performance Standards for Hillside Development in Section 17.20.150. Grading shall be prohibited on slopes of thirty (30) percent or greater except where authorized through permit or site plan approval in compliance with Chapter 17.62.

3. 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.).

4. 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 two hundred (200) feet in length shall be landform graded in compliance with the grading provisions of the Performance Standards for Hillside Development in Section 17.20.150, 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 four thousand five hundred (24,500) square feet, or when the total graded area of the lot is more than nine thousand (9,000) square feet. The maximum allowed slope shall be determined for cuts and fills by subsections (B) and (C) of this section.

5. Archeological Resources. If archeological resources are unearthed or discovered during any construction activities, construction activities shall cease, the community development director and city engineer shall be notified, and the proper disposition of resources shall be accomplished as required by Chapter 17.36.

6. Grading in Hazardous Areas. Grading proposed within areas determined by the city engineer to be subject to geologic, flooding or fire hazards shall comply with applicable provisions of the seismic and geologic hazards management, storm water management and flooding, and fire hazard management performance standards of Section 17.20.150.

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 city engineer waives these standards for minor cuts not intended to support structures or surcharges.

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. Variable slope ratios shall be used when required by subsection (A)(4) of this section.

2. Drainage and Terracing. Drainage and terracing of cuts shall be provided as required by subsection (D) of this section.

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 city engineer waives these standards for minor fills not intended to support structures.

1. Fill Location. Fill slopes shall not be constructed on natural slopes that are steeper than two feet horizontal to one foot vertical.

2. Preparation of Ground. Fill slopes shall not be constructed on natural slopes steeper than two units horizontal to one unit vertical (fifty (50) percent slope). The ground surface shall be prepared to receive fill by removing vegetation, topsoil and other unsuitable materials (including any existing fill that does not meet the requirements of this chapter), and scarifying the ground to provide a bond with the fill material.

Subdrains shall be provided under all fills placed in natural drainage courses and in other locations where seepage is evident, except where the geotechnical engineer or engineering geologist recommends otherwise. Such sub-drainage systems shall be of a material and design approved by the geotechnical engineer and acceptable to the city engineer. The geotechnical engineer shall provide continuous inspection during the process of subdrain installations. The location of the subdrains shall be shown on a plan prepared by the geotechnical engineer. Excavations for the subdrains shall be inspected by the engineering geologist when such subdrains are included in the recommendations of the engineering geologist.

3. Benching. Where existing grade is at a slope steeper than five units horizontal to one unit vertical (twenty (20) percent) and the depth of the fill exceeds five feet (1.5 m), benching shall be provided into sound bedrock or material determined to be competent by the geotechnical engineer. The ground preparation shall be in accordance with Figure 15.11.20.01 or as determined by the geotechnical engineer. When fill is to be placed over a cut, a key shall be provided which is at least ten (10) feet (3.0 m) in width and two feet (0.6 m) in depth. The area beyond the toe of fill shall be sloped for sheet overflow or a paved drain shall be constructed thereon. The geotechnical engineer or engineering geologist or both shall inspect and approve the cut as being suitable for the foundation and placement of fill material before any fill material is placed on the excavation.

[Figure]

Figure 15.11.20.01

4. 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 twelve (12) inches shall be buried or placed in fills, except where the city engineer allows the placement of larger rock when the geotechnical 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 twelve (12) inches in maximum dimension shall be placed ten (10) feet or more below grade, measured vertically;

c. Rocks shall be placed so as to ensure filling all voids with well graded soil;

d. No rock shall be within ten (10) feet of rough grade, if any portion of the rock is greater than six inches in diameter. No rock may constitute more than twenty (20) percent of the engineered fill without special provisions provided by the geotechnical engineer. Remaining fill materials shall consist of a suitable gradation as recommended by the geotechnical engineer and approved by the city engineer.

e. The location of oversized rock dispersal areas shall be shown on the as-built plan.

5. Fill Placement. Fills shall be constructed in layers. The loose thickness of each layer of engineered fill placement material before compaction shall not exceed eight inches or as determined by a geotechnical engineer and approved by the city engineer. 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. For engineered grading, the geotechnical engineer shall provide sufficient inspections during the preparation of the natural ground and the placement and compaction of the fill to ensure that the work is performed in accordance with the conditions of plan approval. The geotechnical engineer shall provide continuous inspection during the entire fill placement and compaction of fills.

6. Depth of Fill. The depth of fill from the substructure to finished grade across a certified rough grading and building pad shall be consistent with surrounding soil and shall not exceed the depth recommended by the geotechnical engineer.

7. Compaction. All fills shall be compacted to a minimum of ninety (90) percent of maximum density or as justified by the geotechnical engineer and approved by the city engineer. Relative compaction shall comply with the following compaction density where applicable:

i. Fills deeper than twenty-five (25) feet shall be compacted at a minimum of ninety-three (93) percent of maximum density.

ii. Fills deeper than fifty (50) feet in thickness, shall be compacted at a minimum of ninety-five (95) percent of maximum density, with additional special provisions provided by geotechnical engineer and approved by city engineer.

iii. The upper twelve (12) inches of pavement soil sub grade shall be shall be compacted at a minimum of ninety-five (95) percent of maximum density.

iv. All utility trench backfill (above spring line) shall be compacted at a minimum of ninety-five (95) percent of maximum density.

8. 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. Variable slope ratios shall be used when required by subsection (A)(4) of this section.

9. 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 set forth in this subsection, 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 foot vertical, except where otherwise required on approved grading plans by the city engineer. Additional standards applicable to the provision of storm drainage facilities as part of grading projects are established by Section 15.11.100.

1. Terraces. Terraces at least eight feet in width shall be established at not more than thirty-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 midheight.

a. For all cut or fill slopes greater than sixty (60) feet and up to one hundred twenty (120) feet in vertical height, one terrace at approximately midheight shall be twenty feet in width. Terrace widths and spacing for cut and fill slopes greater than one hundred twenty (120) feet in height shall be designed by the civil engineer and subject to the approval of the city engineer. Suitable access shall be provided to permit proper cleaning and maintenance.

b. Swales or ditches on terraces shall:

i. Have a minimum gradient of five percent and a maximum gradient of twelve (12) percent;

ii. Be paved with reinforced concrete not less than three inches in thickness, reinforcement with six inch by six inch, number ten by number ten welded wire fabric or equivalent reinforced centered in the concrete slab, or an equivalent provided by the project geotechnical engineer and approved by the city engineer.

iii. Have a minimum depth 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 thirteen thousand five hundred (13,500) square feet (projected), or a horizontal run of no more than three hundred (300) lineal feet 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 city engineer and/or other appropriate jurisdiction as a safe place to deposit the waters. Erosion of ground in the area of discharge shall be prevented by installation of nonerosive downdrains or other approved devices.

4. Building Pad Drainage. Building pads shall have a minimum drainage gradient of two percent toward approved drainage facilities.

5. Interceptor Drains. Paved interceptor drains shall be installed along the top of all graded slopes greater than five feet in height receiving drainage from a slope with a tributary width greater than thirty (30) 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 twelve (12) inches and a minimum paved width of thirty (30) inches measured horizontally across the drain. The slope of the drain shall be approved by the city engineer, but shall not be less than fifty (50) units horizontal to one unit vertical (two percent).

6. Drainage Facility Design. Nonundergrounded drainage facilities shall be designed with integral color (e.g., muted earth tones and other similar colors) and materials (e.g., rock, landscaping and other similar materials) to minimize visibility. Unless otherwise approved by the city engineer, down-drains on highly visible slopes shall be installed underground.

7. Berms. Berms used for slope protection at the top of slopes, shall be at least one foot above the certified finished pad elevation and at least four feet wide.

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. No excavations or construction activities shall remove the lateral confining pressure of any adjacent property without the completion of city approved protection measures. 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.

F. Drainage Across Property Lines. Drainage across property lines shall not exceed that which existed prior to grading. Excess or concentrated drainage shall be contained on site or directed to an approved drainage facility. Erosion of the ground in the area of discharge shall be prevented by installation of nonerosive down drains or other devices approved by the city engineer.

(Ord. No. 2010-268, § 1, 1-27-2010)

Grading shall be prohibited from October 1 st through April 15 th , unless the city engineer 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.

(Ord. No. 2010-268, § 1, 1-27-2010)

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 a grading permit or an oak tree permit issued pursuant to Chapter 17.32 shall be protected from damage by proper grading techniques and fencing, and no grading or heavy equipment operations shall be conducted within the protected zone of the tree, as that term is defined in Chapter 15.12.

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.

(Ord. No. 2010-268, § 1, 1-27-2010)

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 an 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 hydro-mulching, 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 one thousand (1,000) square feet of land area. Other revegetation methods offering equivalent protection may be approved by the city engineer. 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 15.11.030) shall be installed within thirty (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.

(Ord. No. 2010-268, § 1, 1-27-2010)

Grading, dredging or diking shall not alter any intermittent or perennial stream, or natural body of water shown on any United States Geological Survey (USGS) 7-1/2 minute topographic map, except as permitted through approval of a grading permit in compliance with this article, any land use permits required by Title 17, and any permits required by the California Department of Fish and Game or Army Corp of Engineers.

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 placed within watercourses shall have suitable protection against erosion during flooding.

4. Grading equipment shall not cross or disturb channels containing live streams without siltation control measures approved by the city engineer in place.

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 city engineer 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.

(Ord. No. 2010-268, § 1, 1-27-2010)

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 15.11.70.01.

A. Top of 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 (H/5) of the vertical height of the cut with a minimum of two feet and a maximum of ten (10) feet unless the geotechnical engineer demonstrates to the satisfaction of the city engineer that a reduced setback would be safe and no increased hazard to any habitable structure will occur. 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 (H/2), with a minimum of two feet and a maximum of twenty (20) feet unless the geotechnical engineer demonstrates to the satisfaction of the city engineer that a reduced setback would be safe and no increased hazard to any habitable structure will occur. Where a fill slope is to be located near a property line and the adjacent property is developed, the city engineer 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 15.11.020(E), 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.

[Figure]

C. Setback Exceptions. The city engineer may approve alternatives to the setbacks required by subsections (A) and (B) of this section, 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 one hundred (100) feet of any area determined by the city engineer to be an environmentally sensitive habitat area, or from the top of the bank of a watercourse as determined by the city engineer, unless the grading is approved as a discretionary project in compliance with Section 15.10.050(A) (2), and is subject to environmental review in compliance with Section 15.10.040(B).

(Ord. No. 2010-268, § 1, 1-27-2010)

A. Design and Construction. Drainage systems and facilities that are proposed within existing or future public rights-of-way shall be designed and constructed as set forth in Section 17.46.030 of Title 17. The design and construction of drainage facilities required for cuts and fills are subject to Section 15.11.040(D). Other drainage systems and facilities shall be designed in compliance with good engineering practices.

B. Natural Channels and Runoff. Proposed grading projects shall include design provisions to retain off-site natural drainage patterns, and limit the quantities and velocities of peak runoff to predevelopment levels.

C. Areas Subject to Flooding. Grading or structures are not permitted in an area determined by the city engineer 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 Section15.11.030, 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 city engineer. 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 at a minimum the current federal floodplain management regulations as defined in the National Flood Insurance Program authorized by United States Code Sections 4001-4128 and contained in Title 44 of the Code of Federal Regulations, Part 59 et seq., which are adopted and incorporated into this chapter by reference as though they were fully set forth here.

2. Letter of Map Revision (LOMR). Where the city engineer 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.

(Ord. No. 2010-268, § 1, 1-27-2010)

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 and/or permittees 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 city engineer 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 twenty-four-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.

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 city engineer 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 city engineer may limit or halt all activities on the site until adequate dust prevention and control measures are achieved. The city engineer 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 and Enforcement. If it is determined that a property in violation of this section, the property owner and/or contractor will have twenty-four (24) hours to bring the site into compliance. If after twenty-four (24) hours, the site is not brought into compliance or an extension of time has not been granted by the city engineer, the building official may, at any time thereafter, determine the site to be substandard property and serve a written notice of violation. As substandard property, the site will be subject to all the provisions of Chapter 99 of the latest edition of Title 26 of the California Building Code as adopted by the city. Thereupon, the city engineer may 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 city engineer may cause the owner of the site to be prosecuted as a violator of this code, or the city engineer 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 permittee of the responsibility to implement whatever additional measures may be required by the city engineer 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.

(Ord. No. 2010-268, § 1, 1-27-2010)

Drainage improvements for site runoff, including but not limited to runoff from all roadways and other impervious surfaces, shall be engineered to minimize erosion through the appropriate use of rocked culvert inlets and outfalls, energy dissipators, check dams, cribbing, riprap, proper location of culverts, revegetation of exposed slopes (see Section 15.11.070), and minimizing the use of artificial slopes. Erosion and sediment shall be controlled as provided by this section.

A. Best Management Practices for Projects Under Construction. The following best management practices 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. Runoff Prohibited. Runoff, sediment and construction waste from construction sites and parking areas shall not leave the site.

2. Grading During the Rainy Season. Should grading be permitted during the rainy season (see Section 15.11.030), 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.

3. Slope Surface Stabilization. Temporary mulching, seeding or other suitable stabilization measures approved by the city engineer 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.

4. 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.

5. 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 or adjoining properties. Soil piles shall be covered until the soil is either used or removed.

6. Removal of Off-Site Sediments. Any sediment 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 city engineer, a temporary sediment barrier shall be installed.

7. 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 construction site shall be allowed to leave the site.

8. Erosion Control Devices. In order to prevent polluting sediment discharges, erosion and sediment control devices shall be installed as required by the city engineer for all grading and filling except as allowed by Chapter 8.26. 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, detention ponds, sediment ponds, or infiltration pits, or downdrains, chutes or flumes.

B. Final Erosion Control Measures. Within thirty (30) days after completion of grading, 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 15.11.070 unless covered with impervious or other improved surfaces authorized by approved plans. Erosion controls may include any combination of mechanical or vegetative measures, including those described in USDA National Resources Conservation Service Bulletin 347.

(Ord. No. 2010-268, § 1, 1-27-2010)