Mission Viejo Municipal Code Div. 13 Erosion Control

(a) Erosion prevention is to be used as the most important measure for keeping sediment on site during construction. Sediment controls are to be used as a supplement to erosion prevention for keeping sediment on site during construction.

(b) The faces of cut and fill slopes and project site shall be prepared and maintained to control against erosion in accordance with this division. Where cut slopes are not subject to erosion due to the erosion-resistant character of the materials, such protection may be omitted upon approval by the director.

(c) An effective erosion control system shall be employed to control erosion and provide safety. Applicable erosion control, sediment control, wind erosion, tracking control, nonstormwater management and waste management and materials, pollution control best management practices (BMPs) from city engineering standard plans and the most current California Stormwater Quality Association Construction BMP Handbook shall be implemented for each project.

(d) No grading work in excess of 200 cubic yards will be allowed during the rainy season on any single grading site under permit unless an erosion control system has been approved or waived by the director.

(e) Paved streets, sidewalks and other improvements shall be maintained in a neat and clean condition free of loose soil, construction debris and trash. Street sweeping or other equally effective means shall be used on a regular basis to prevent storm flows from carrying sediment and debris outside the project boundaries. Watering shall not be used to clean streets unless the water is fully recovered prior to entering the city storm drain system and disposed of properly into the sanitary sewer system or another approved location.

(f) The civil engineer or other qualified individual who prepared the grading plan and designed the erosion control devices shall be responsible for inspection and modification of the devices, as necessary, during the rainy season. Significant modifications to erosion control shall be approved by the director.

(g) Desilting facilities designed for 25-year storm intensity shall be provided at drainage outlets from the graded site.

(h) Desilting basins shall be designed to provide a minimum desilting capacity equal to the current city standards as established by the director.

(i) Desilting basins shall be constructed around the perimeter of projects whenever feasible when it provides improved maintenance access from paved roads during wet weather.

(j) Desilting basins constructed of compacted earth shall be compacted to a relative compaction of 90 percent of maximum density. A soil engineering report, prepared by the soil engineer, which includes the type of field testing performed, location and results of testing, shall be submitted to the director for approval upon completion of the desilting basins.

(k) Equipment and workers for emergency work shall be made available at all times during the rainy season. Necessary materials shall be available on-site and stockpiled at convenient locations to facilitate rapid construction of temporary devices when rain is imminent.

(l) Slope stabilization must be used on all active slopes in preparation for and during the rainy events regardless of season and on all active and inactive slopes during the rainy season.

(m) Erosion protection shall consist of effective planting of all slopes in excess of five feet high unless otherwise approved by the director. Slopes exceeding 15 feet high may require an adequate sprinkler system, as determined by the director.

(n) City-approved protection for the slopes shall be installed as soon as practicable, which may be prior to rough grade approval. Effective planting shall be installed and fully germinated, and shall effectively cover the required slopes prior to final approval unless otherwise approved by the director.

(o) The erosion control provisions shall take into account drainage patterns during the current and future phases of grading throughout the rainy season.

(p) All removable protective devices shown shall be in place at the end of each working day when the five-day rain probability forecast exceeds 40 percent.

(q) Graded areas around the tract perimeter must drain away from the face of slopes at the conclusion of each working day.

(r) Vegetation clearing and brushing activities shall not be initiated during the rainy season on any sites which are not adequately protected with desilting basins or other temporary drainage or control measures.

(s) Erosion control plans shall consider preservation of natural hydrologic features, riparian buffers and corridors, and clearly indicate the areas not to be disturbed.

(t) In addition to requirements specified above, the permittee shall perform all work in accordance with the water quality requirements.

(u) Any violation of an applicable federal- or state-issued storm water permit, or failure to conform to the city's water quality requirements prepared pursuant to such a permit or pursuant to this chapter, or failure to comply with storm water related provisions of a city-issued grading permit or of a grading plan prepared to secure such a permit, is also a violation of this chapter.

(Ord. No. 10-286, § 2, 12-6-10)

Erosion control plans prepared in accordance with subarticle 13 of the grading manual and any applicable storm water permit issued to the city or to the permittee shall be submitted to the director for approval by September 1 each year for all projects under grading permits. Plans are required to be submitted even though no revisions to the erosion control are required. The erosion control plan may be waived for grading projects on single residential lot projects providing that an erosion control system, meeting the approval of the director, has been installed, placed, planted or constructed prior to the start of the city's defined rainy season.

(Ord. No. 10-286, § 2, 12-6-10)

(a) After each rainstorm, silt and debris shall be removed from the erosion control system devices including check berms and desilting basins and the basins pumped dry. Slope protection measures damaged by a rainstorm shall be immediately repaired.

(b) After each rainstorm, the performance of the erosion control system shall be evaluated and revised and repaired as necessary.

(c) Devices shall not be moved or modified without the approval of the director.

(d) The contractor shall be responsible and shall take necessary precautions to prevent public trespass onto areas where impounded water creates a hazardous condition.

(e) The contractor and permittee or project owner shall be responsible for continual maintenance of the devices. In the event of failure or refusal by the contractor, permittee or project owner to properly maintain the devices, the director may cause emergency maintenance work to be done to protect adjacent private and public property. The cost shall be charged to the owner and shall include an initial mobilization cost plus the cost of doing the work as contained in division 6.

(f) If the director must cause emergency maintenance work to be done, he may revoke the grading permit in writing. The permit shall not be renewed until an erosion control system approved by the director is installed and a fee of one-half the amount required for the original permit paid by the owner. The Director may waive installation of an erosion control system during the city's defined dry season (nonrainy season).

(g) If any grading subject to section 8.10.340 has commenced on private property without a valid grading permit, the property owner may be required to prepare and implement an erosion control plan which has been approved by the director. In the event of failure by the property owner to install an approved erosion control system, the director may cause emergency work to be done to protect adjacent private and public property. The procedures of section 8.10.420 need not apply for emergency erosion control work between during the city's defined rainy season. The cost shall be charged to the owner in accordance with subsection (e).

(Ord. No. 10-286, § 2, 12-6-10)