Chapter 17.95
EROSION PREVENTION AND SEDIMENT CONTROL
Sections:
17.95.040 Erosion prevention and sediment control plan submission requirements.
17.95.050 Erosion control plan standards.
17.95.060 Plan implementation requirements.
17.95.090 Hillside protection.
17.95.010 Purpose.
The purpose of these standards is to reduce the amount of sediment and pollutants resulting from development, construction, grading, excavating, clearing, and any other activity which accelerates erosion or increases water pollution, from reaching the public storm and surface water system or from directly entering surface waters. The objective is to prevent and control erosion and pollution at its source in order to maintain and improve water quality and reduce downstream impacts. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.020 Applicability.
The erosion prevention and sediment control plan shall be reviewed by the public works director and city engineers. All additional fees for this review shall be paid by the applicant. An erosion prevention and sediment control plan shall be required and approved by the public works director and city engineer under any of the following circumstances:
A. Prior to final plat approval for any subdivision or partition, in accordance with RRMC Title 16.
B. Prior to site design review, in accordance with Chapter 17.115 RRMC.
C. No permit for construction of new development or tenant improvements that result in impervious cover greater than 500 square feet within the city and urban growth boundary shall be issued until effects on erosion prevention and sediment control are evaluated. The level of review varies according to the affected area:
1. Level 1: 500 to 1,999 square feet. No erosion prevention and sediment control measures beyond any mitigation measures for pollution reduction or flow control are required.
2. Level 2: 2,000 to 4,999 square feet. Conceptual plans that conform to the erosion prevention and sediment control best management practices shall be submitted and approved.
3. Level 3: 5,000+ square feet. A comprehensive erosion prevention and sediment control study that conforms to RRMC 17.95.050 shall be submitted and approved.
4. Areas smaller than 500 square feet may require review, and a greater level of review for properties between 500 and 4,999 square feet may be necessary when the site is identified as having especially sensitive conditions, including but not limited to wetlands and steep slopes.
D. Farming activities are exempt from the provisions of this chapter; provided, that the specific land area has been cultivated within the last three years.
E. Upon a finding that visible or measurable erosion has entered, or is likely to enter, the public storm and surface water system. As used in this section, “visible or measurable erosion” shall include the following:
1. Depositions of soil or sediment exceeding one cubic foot in volume on a public or private street, adjacent property, or into the surface water management system either by direct deposit, dropping, discharge or as a result of erosion.
2. Flows of water over bare soils, turbid or sediment laden flows, or evidence of on-site erosion such as rivulets or bare soil slopes, where the flow of water is not filtered or captured on the site.
3. Earth slides, mud flows, earth sloughing, or other earth movement which leaves the property of origin.
Nothing in this section shall relieve any person from the obligation to comply with the regulations or permits of any federal, state, or local authority. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.030 Approval standards.
The public works director shall make the following affirmative findings prior to approval of an erosion control plan:
A. The project has been designed to minimize disturbance of natural topography, native vegetation and soils, consistent with applicable provisions of RRMC 17.95.090 (Hillside protection) and Chapter 15.55 RRMC (Flood Damage Prevention).
B. The site design maximizes the preservation of healthy trees, understory shrubs and ground cover.
C. The plan complies with the applicable technical guidelines, as determined by the public works director. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.040 Erosion prevention and sediment control plan submission requirements.
The required level 3 erosion prevention and sediment control plan shall include a narrative description and scaled drawings which address:
A. The physical characteristics of the site, including a map of existing topography at two-foot contour intervals, the location of water areas, and a narrative description of soil characteristics. The requirement for a two-foot contour map may be waived by the city where this information is not readily available, and erosion potential is minor.
B. The nature of the proposed development, including any phasing plans, which may affect soils or create soil erosion. Areas of excavation, grubbing, clearing, stockpiling, or vegetation removal shall be specifically identified.
C. Specific erosion control measures and practices to be used to demonstrate compliance with RRMC 17.95.050.
D. Submitted plans shall be stamped by a professional engineer registered in Oregon. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.050 Erosion control plan standards.
In addition to compliance with relevant portions of the hillside protection regulation (RRMC 17.95.090) and floodway and floodplain regulations, the required erosion prevention and sediment control plan shall comply with the following standards:
A. Control Measures. Specific methods of soil erosion and sediment control shall be used during construction to minimize visible and measurable erosion. In no case shall soil erosion and sediment transport from the site exceed the rate of one ton per acre per year. These methods shall include all of the following:
1. The land area to be grubbed, stripped, used for temporary placement of soil, or to otherwise expose soil shall be confined to the immediate construction site only.
2. The duration of exposure of soils shall be kept to a minimum during construction. Exposed soils shall be covered by mulch, sheeting, temporary seeding or other suitable material following grading or construction, until soils are stabilized. During the rainy season (November through May), soils shall not be exposed for more than seven consecutive days. All disturbed land areas which will remain unworked for 21 days or more during construction shall be mulched and seeded.
3. During construction, runoff from the site shall be controlled, and increased runoff and sediment resulting from soil disturbance shall be retained on site. Temporary diversions, sediment basins, barriers, check dams, or other methods shall be provided as necessary to hold sediment and runoff.
4. A stabilized pad of gravel shall be constructed and maintained at all entrances and exits to the construction site to prevent soil deposits on the roadway or in the drainage ways. The stabilized gravel pad shall be the only allowable entrance or exit to the site.
5. Topsoil removal for development shall be stockpiled and reused on site to the degree necessary to restore disturbed areas to their original or enhanced condition, or to assure a minimum of six inches of stable topsoil for revegetation. Additional soil shall be provided if necessary to support revegetation.
6. The removal of all sediments which are carried into the streets, or onto adjacent property, is the responsibility of the developer. The applicant shall be responsible for cleaning and repairing streets, catch basins, and adjacent properties, where such properties are affected by sediments or mud. In no case shall sediments be washed into storm drains, ditches, drainage ways, streams, or wetlands.
7. Any other relevant provision of the adopted erosion control manual, required by the city.
B. Restoration of Vegetation. The developer shall be responsible for revegetating public and private open spaces, utility easements, and undeveloped rights-of-way in accordance with an approved schedule of installation.
1. If the vegetation existing prior to site development is nonnative or invasive, it shall be replaced with native or noninvasive plant species.
2. Temporary measures used for initial erosion control shall not be left in place permanently.
3. Work areas on the immediate site shall be carefully identified and marked to reduce potential damage to trees and vegetation.
4. Trees shall not be used as anchors for stabilizing working equipment.
5. During clearing operations, trees and vegetation shall not be permitted to fall or be placed outside the work area.
6. In areas designated for selective cutting or clearing, care in felling and removing trees and brush shall be taken to avoid injuring trees and shrubs to be left in place.
7. Stockpiling of soil, or soil mixed with vegetation, shall be removed prior to completion of the project.
C. Schedule of Installation. A schedule of planned erosion control and revegetation measures shall be provided, which sets forth the progress of construction activities and mitigating erosion control measures.
D. Responsible Person. The developer shall designate a specific person to be responsible for carrying out the erosion prevention and sediment control plan.
E. Reference Authority. The erosion prevention and sediment control planning and design manual developed in partnership with the United Sewerage Agency of Washington County et al., revised December 2000, shall be the primary guide for the city in establishing and reviewing erosion control techniques, methods and requirements. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.060 Plan implementation requirements.
An approved erosion prevention and sediment control plan shall be implemented and maintained as follows:
A. Plan Approval Required Prior to Clearing or Grading. No grading, clearing or excavation of land requiring an erosion prevention and sediment control plan shall be undertaken prior to approval of the erosion prevention and sediment control plan.
B. Implementation. The developer shall implement the measures and construct facilities contained in the approved erosion prevention and sediment control plan in a timely manner.
1. During active construction, the developer shall inspect erosion prevention and control measures daily during rainy periods. In all cases, the developer shall be responsible for maintenance, adjustment, repair and replacement of erosion control measures to ensure that they are functioning properly without interruption.
2. Eroded sediment shall be removed immediately from pavement surfaces, off-site areas, and from the surface water management system, including storm drainage inlets, ditches and culverts. In the event that sediment is inadvertently deposited in a wetland or stream, the developer shall immediately contact the city and coordinate remedial actions.
3. Water containing sediment shall not be flushed into the surface water management system, wetlands or streams without first passing through an approved sediment filtering facility or device.
4. When required by the city, the developer shall maintain written records of all site inspections of erosion control measures which shall be provided to the city upon request.
5. The developer shall call for city inspection, prior to the clearing, grading, or excavation for any building, to certify that erosion control measures are installed in accordance with the erosion prevention and sediment control plan. The city may inspect the property at any time during construction.
C. Correction of Ineffective Measures. If the facilities and techniques approved in the erosion prevention and sediment control plan are not effective or sufficient to meet the purpose of this section, based on an on-site inspection, the city may require a revised plan.
1. The revised erosion prevention and sediment control plan shall be provided within five working days of written notification by the public works director.
2. The developer shall implement the revised plan within five working days of approval by the city.
3. In cases where serious erosion is occurring, the city may require the developer to install interim control measures immediately, before submission of the revised erosion prevention and sediment control plan.
D. Additional Standards. The following additional standards shall apply:
1. Pollutants such as fuels, lubricants, raw sewage, and other harmful materials shall not be discharged into or near rivers, streams, or impoundments, and shall be properly stored and disposed of.
2. Discharge of water into a stream, wetland or impoundment shall not result in violation of the state temperature standard.
3. All sediment-laden water from construction operations shall be routed through tilling basins, filtered, or otherwise treated to reduce the sediment load, and prevent violation of the state turbidity rule.
E. Storage. All erodible or toxic materials delivered to the job site shall be covered and protected from the weather and stored according to appropriate health and safety guidelines.
1. Such materials shall not be exposed during storage.
2. Waste material, rinsing fluids, and other such material shall be disposed of in such manner that pollution of groundwater, surface water, or air does not occur.
3. In no case shall toxic materials be dumped into drainage ways or onto land.
F. Contaminated Soils. Where the construction process reveals soils contaminated with hazardous materials or chemicals, the contractor shall stop work immediately, ensure that no contaminated material is hauled from the site, remove the workforce from the contaminated area, leave all machinery and equipment, secure the area from access by the public until such time as a mitigation team has relieved the contractor of that responsibility, notify the city of the situation upon its discovery, and prohibit employees who may have come in contact with the contaminated material from leaving the site until released by the city.
G. Duration of Maintenance. Continuing maintenance after development pursuant to the erosion prevention and sediment control plan, including revegetation of all graded areas, shall be the responsibility of the developer, subsequent developers or property owners.
1. Erosion prevention and control measures shall be maintained during construction and for one year after development is completed. If it is found that soils are not completely stabilized after one year, the city may extend this period.
2. The city may, upon a finding that soils are completely stabilized, reduce this period. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.070 Security.
After an erosion prevention and sediment control plan is approved by the public works director and city engineer and prior to construction or grading, the applicant shall provide a performance bond or other financial guarantee in the amount of 100 percent of the value of the erosion prevention/control necessary to stabilize the site and maintain water quality. Any financial guarantee instrument proposed other than a performance bond shall be approved by the city administrator.
A. Duration. The financial guarantee instrument shall be in effect for a period of at least two years, and shall be released when the public works director determines that the site has been stabilized. All or a portion of the security retained by the city may be withheld for a period of up to five years beyond the two-year maintenance period, if it has been determined by the city that the site has not been sufficiently stabilized against erosion.
B. Exemptions. Individual lots zoned for single-family and multifamily residential use prior to the effective date of the ordinance codified in this section shall be exempt from these security requirements.
C. Conflict. Due to the immediate threat to the public health, safety and welfare posed by failure to comply with the strict provisions of the erosion control measures required under this section, this section shall supersede the more general provisions in other sections of this title where they exist. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.080 Enforcement.
Each violation of any provision of this chapter, or any failure to carry out the conditions of any approval granted pursuant to this chapter, shall be unlawful and a civil infraction subject to the enforcement provisions in Chapter 17.130 RRMC.
A. Additional Penalties. In addition to those penalties available under Chapter 17.130 RRMC, the city may enforce the following additional penalties:
1. Issue a stop work order where erosion control measures are not being properly maintained or are not functioning properly due to faulty installation or neglect.
2. Refuse to accept any development permit application, revoke or suspend any development or building permit, or deny occupancy of the subject property until erosion control measures have been installed properly and maintained in accordance with this chapter.
B. The owner of the property from which the erosion occurs, together with any person or parties who cause such erosion, shall be responsible for mitigating the impacts of the erosion and for preventing future erosion.
C. Upon request of the city administrator or at the direction of the city council, the city attorney may institute appropriate action in any court to enjoin development of a site or building project which is in violation of this chapter, or to require conformance with this chapter. [Ord. 23-418-O § 124 (Exh. A-4)].
17.95.090 Hillside protection.
It is the purpose of this section to provide supplemental development regulations to underlying zones, which ensure that development occurs in such a manner as to protect the natural and topographic character, environmental resources, aesthetic qualities and restorative value of these areas, as well as the public health, safety, and general welfare, by ensuring that development does not create soil erosion, sedimentation of lower slopes, slide damage, flooding problems, and severe cutting or scarring. It is the intent of these development standards to encourage a sensitive form of development and to allow for a reasonable use that complements the natural and visual character of the city. Hillside protection shall be provided on slopes of 15 percent or greater or unconstrained slopes within 30 feet of the top of escarpments associated with rivers or streams.
A. Hillside Development Standards.
1. Steep Slopes.
a. Steep slope areas include all areas in the city where the slope of the land is 35 percent or greater.
b. Existing parcels where all existing terrain is 35 percent or greater shall be considered buildable for one dwelling unit only.
c. All grading, retaining wall design, drainage, and erosion control plans shall be designed by a geotechnical expert in compliance with subsection (C)(2) of this section.
d. Existing parcels where all existing terrain is 35 percent or greater cannot be subdivided or partitioned.
2. Constrained Slopes.
a. Constrained slope areas include all areas where the slope of the land is between 15 percent and 35 percent.
b. The impervious surface area of any residential lot or commercial or industrial site (including driveways, sidewalks, structures, swimming pools, and any other area not covered by vegetation) shall not exceed 30 percent of the constrained slope area;
c. At least half the constrained slope area shall remain in, or be planted in, approved native vegetation. The existing tree canopy shall be retained wherever possible, and shall be considered in meeting this standard.
B. All Hillside Developments.
1. Specific determination of steep slope and constrained slope areas shall be based on a topographic map and field survey prepared by an engineer or surveyor registered in Oregon, and provided by the applicant or property owner(s).
a. Where development, excavation or vegetation removal is proposed for areas with 15 percent or greater slope, an on-the-ground topographical survey shall be prepared for the entire property. The survey shall show trees or tree clusters and two-foot contours.
b. Areas with between 15 and 35 percent slopes, and areas with 35 percent and greater slopes, shall be specifically indicated on the required survey maps.
2. All newly created lots either by subdivision or partition shall contain a building envelope with a slope of 35 percent or less.
3. Development shall not result in cuts or fills in excess of three feet except for basement construction unless specifically approved by the city.
4. If development is proposed on constrained or steep slope areas, a mitigation plan for disturbed areas on constrained or steep slope areas shall be prepared and implemented. This plan shall provide for the replanting and maintenance of approved native plant species designed to achieve predisturbance conditions.
5. Residential roof lines shall not exceed the natural ridgeline when viewed from the public street providing access to the property.
6. Circulation.
a. The location, alignment design, grade width, and capacity of roads within the development shall conform to city engineering standards. However, the use of public and private lanes shall be encouraged in the hill areas to reduce the disturbance of the natural landscape. The width of these lanes shall be allowed to be as narrow as public safety and traffic generation will permit.
b. Loop and split, one-way street sections, and occasional steep street grades shall be allowed to fit terrain and minimize grading and exposed slopes.
c. Streets and lanes in the hill areas shall be laid out to encourage slow speed traffic and respect the natural topography of the area.
d. Street grades may be permitted up to 15 percent, provided they do not exceed 200 feet in length, whereby they must be reduced to 10 percent or less for a minimum length of 20 feet. The overall grade shall not exceed 10 percent.
e. Culverts, bridges and other drainage structures shall be placed to encourage drainage in established drainage ways and as provided in Chapter 16.15 RRMC. Additional road construction improvements may be required in areas exhibiting poor soil stability.
f. Circulation shall, when feasible, be designed to allow for separation of vehicular, pedestrian, bicycle, and hiking trails. The circulation system shall, when feasible, be developed throughout the hill areas, to provide connections between park areas and scenic easements in order to help maximize leisure opportunities of the hills. Trails may be accepted by the appropriate jurisdiction in fee or easement.
g. Walkways shall be required when determined to be needed for public safety and convenience. When required, walkways shall be of minimum width of four feet unless a greater need is shown. Walkways shall be constructed of a material suitable for use in the particular area and shall be located as necessary to provide maximum pedestrian safety and preservation of the character of the area.
h. Driveways shall be designed to a grade and alignment that will provide the maximum safety and convenience for vehicular and pedestrian use. Collective private driveways shall be encouraged where their utilization will result in better building sites and lesser amount of land coverage than would result if a public road were required.
i. Minimum standards for private easement construction within the steep and constrained slope areas shall be as follows:
i. Minimum travel service width: 12 feet.
ii. Minimum vertical clearance: 14 feet.
iii. Minimum horizontal clearance: 16 feet.
iv. Maximum intermittent grade: 15 percent for 200 feet.
v. Maximum sustained grade: 10 percent.
j. Whenever private drives are permitted, it shall be the responsibility of the benefited property owners to maintain the private easement or driveway established in accordance with this chapter.
7. Disturbed areas shall be replanted in approved native vegetation and tree cover.
8. The applicant’s engineering plans shall certify that runoff and sedimentation from the site will not increase more than 10 percent above conditions present on the site as of the effective date of the ordinance codified in this section.
9. The applicant’s engineer shall provide a construction erosion control plan and water quality plan, consistent with the provisions of RRMC 17.95.010 through 17.95.080.
C. Required Reports.
1. Geotechnical Studies. Where division or development is proposed for areas with 15 percent to 35 percent slope, and development is proposed for areas with slopes of 35 percent or greater, a geologic assessment and a geotechnical report, prepared by a geotechnical expert, shall be provided by the applicant, indicating that the site is stable for the proposed use and development. These studies shall include the following information:
a. Index map.
b. Project description to include location, topography, drainage, vegetation, discussion of previous work and discussion of field exploration methods.
c. The geologic assessment shall include:
i. Site geology, based on a surficial survey, to include site geologic maps, description of bedrock and surficial materials, including artificial fill, locations of any faults, folds, etc., and structural data including bedding, jointing and shear zones, soil depth and soil structure.
ii. Discussion of any off-site geologic conditions that may pose a potential hazard to the site, or that may be affected by on-site development.
iii. Suitability of site for proposed development from a geologic standpoint.
d. The geotechnical report shall also include:
i. Specific recommendations for cut and fill slope stability, seepage and drainage control or other design criteria to mitigate geologic hazards.
ii. If deemed necessary by the engineer or geologist to establish whether an area to be affected by the proposed development is stable, additional studies and supportive data shall include cross-sections showing subsurface structure, graphic logs with subsurface exploration, results of laboratory test and references.
iii. Signature and registration number of the engineer and/or geologist.
iv. Additional information or analyses as necessary to evaluate the site.
v. Inspection schedule for the project as required in subsection (G) of this section.
vi. Location of all irrigation canals and major irrigation pipelines.
2. Hillside Grading and Erosion Control Plan. All development shall provide plans conforming with the following items:
a. All grading, retaining wall design, drainage, and erosion control plans for development on hillside lands shall be designed by a geotechnical expert.
b. All cuts, grading or fills shall conform to Chapter 70 of the International Building Code. Erosion control measures on the development site shall be required to minimize the solids in runoff from disturbed areas.
c. For development other than single-family homes on individual lots, all grading, drainage improvements, or other land disturbances shall only occur from May 1st to October 31st. Excavation shall not occur during the remaining wet months of the year.
d. Erosion control measures shall be installed and functional by October 31st. Up to 30-day modifications to the October 31st date and 45-day modification to the May 1st date may be made by the city planner, based upon weather conditions and in consultation with the project geotechnical expert. The modification of dates shall be the minimum necessary, based upon evidence provided by the applicant, to accomplish the necessary project goals.
e. Grading – Cuts. On all cut slopes, the following standards shall apply:
i. Cut slope angles shall be determined in relationship to the type of materials of which they are composed. Where the soil permits, limit the total area exposed to precipitation and erosion. Steep-cut slopes shall be retained with stacked rock, retaining walls, or functional equivalent to control erosion and provide slope stability when necessary. Where cut slopes are required to be laid back (1:1 or less steep), the slope shall be protected with erosion control netting or structural equivalent installed per manufacturer’s specifications and revegetated.
ii. Exposed cut slopes, such as those for streets, driveway accesses, or yard areas greater than seven feet in height, shall be terraced. Cut faces on a terraced section shall not exceed a maximum height of five feet. Terrace widths shall be a minimum of three feet to allow for the introduction of vegetation for erosion control. Total cut slopes shall not exceed a maximum vertical height of 15 feet. The top of cut slopes not utilizing structural retaining walls shall be located a minimum setback of one-half the height of the cut slope from the nearest property line. Cut slopes for structure foundations encouraging the reduction of effective visual bulk, such as split pad or stepped footings, shall be exempted from the height limitations of this subsection.
iii. Revegetation of cut slope terraces shall include the provision of a planting plan, introduction of topsoil where necessary, and the use of irrigation if necessary. The vegetation used for these areas shall be native or species similar in resource value which will survive, help reduce the visual impact of the cut slope, and assist in providing long-term slope stabilization. Trees, bush-type plantings and cascading vine-type plantings may be appropriate.
f. Grading – Fills. On all fill slopes, the following standards shall apply:
i. Fill slopes shall not exceed a total vertical height of 20 feet. The toe of the fill slope area not utilizing structural retaining shall be a minimum of six feet from the nearest property line.
ii. Fill slopes shall be protected with an erosion control netting, blanket or functional equivalent. Netting or blankets shall only be used in conjunction with an organic mulch such as straw or wood fiber. The blanket must be applied so that it is in complete contact with the soil so that erosion does not occur beneath it. Erosion netting or blankets shall be securely anchored to the slope in accordance with manufacturer’s recommendations.
iii. Utilities. Whenever possible, utilities shall not be located or installed on or in fill slopes. When determined that it is necessary to install utilities on fill slopes, all plans shall be designed by a geotechnical expert.
iv. Revegetation of fill slopes shall utilize native vegetation or vegetation similar in resource value and which will survive and stabilize the surface. Irrigation may be provided to ensure growth if necessary. Evidence shall be required indicating long-term viability of the proposed vegetation for the purposes of erosion control on disturbed areas.
g. Site Grading. The grading shall be reviewed considering the following factors:
i. No terracing shall be allowed except for the purposes of developing a level building pad and for providing vehicular access to the pad.
ii. Hazardous or unstable portions of the site shall be avoided.
iii. Building pads should be of minimum size to accommodate the structure and a reasonable amount of yard space. Pads for tennis courts, swimming pools and large lawns are discouraged. As much of the remaining lot area as possible should be kept in the natural state of the original slope.
h. Design Standards. The required reports shall include design standards necessary for the engineer and landscape expert to certify that development on slopes of 15 percent or greater, when combined with impacts from development of lesser slopes, will not increase runoff, sedimentation to affected streams or wetlands, erosion, or landslide potential more than 10 percent above base conditions. These requirements shall be incorporated as conditions into the final decision approving the proposed development.
D. Retention in Natural State. All partitions, subdivisions and existing lots with an area greater than one-half acre, an area equal to 25 percent of the total project area, plus the percentage figure of the average slope of the total project area, shall be retained in a natural state. Lands to be retained in a natural state shall be protected from damage through the use of temporary construction fencing or the functional equivalent. For example, on a 25,000-square-foot lot with an average slope of 29 percent, 25 percent plus 29 percent equals 54 percent of the total lot area shall be retained in a natural state. Retention in a natural state of areas greater than the minimum percentage required here is encouraged.
E. Revegetation Requirements. Where required by this chapter, all required revegetation of cut and fill slopes shall be installed prior to the issuance of a certificate of occupancy, signature of a required survey plat, or other time as determined by the city. Vegetation shall be installed in such a manner as to be substantially established within one year of installation.
F. Maintenance, Security, and Penalties for Erosion Control Measures.
1. Maintenance. All measures installed for the purposes of long-term erosion control, including but not limited to vegetative cover, rock walls, and landscaping, shall be maintained in perpetuity on all areas which have been disturbed, including public rights-of-way. The applicant shall provide evidence indicating the mechanisms in place to ensure maintenance of measures.
2. Security. Except for individual lots existing prior to January 1, 1998, after an erosion control plan is approved by the city and prior to construction, the applicant shall provide a performance bond or other financial guarantees in the amount of 120 percent of the value of the erosion control measures necessary to stabilize the site. Any financial guarantee instrument proposed other than a performance bond shall be approved by the city attorney. The financial guarantee instrument shall be in effect for a period of at least one year, and shall be released when the city planner and public works director determine, jointly, that the site has been stabilized. All or a portion of the security retained by the city may be withheld for a period up to five years beyond the one-year maintenance period if it has been determined by the city that the site has not been sufficiently stabilized against erosion.
G. Inspections and Final Report. Prior to the acceptance of a subdivision by the city, signature of the final survey plat on partitions, or issuance of a certificate of occupancy for individual structures, the project geotechnical expert shall provide a final report indicating that the approved grading, drainage, and erosion control measures were installed as per the approved plans, and that all scheduled inspections, as per subsection (C)(1)(d)(ii) of this section, were conducted by the project geotechnical expert periodically throughout the project.
H. Approval Procedure. The city shall approve new development or redevelopment on constrained slope areas only if the proposed use or structure meets all of these conditions:
1. Development standards are met as prescribed under subsection (C) of this section.
2. Adequate protection is utilized to minimize landslide and erosion hazards, consistent with RRMC 17.95.010 through 17.95.080.
3. Notwithstanding the provisions of Chapter 17.105 RRMC, Article I, Variances, an adjustment of up to 20 percent from any dimensional standard in the underlying zoning district may be approved where necessary to avoid construction on slopes of 35 percent or greater or to meet the standards of subsection (C) of this section. [Ord. 23-418-O § 124 (Exh. A-4)].