A. Clearing Permits. A permit is required and shall be issued in accordance with Section 24.10.070 for clearing activities in the following areas:

1. The Tualatin River sub-basins, Johnson Creek Basin Plan District, environmental zones, greenway zones, or natural resource management plans; or

2. Property larger than five acres. Except that no permit shall be required for clearing an area less than 5,000 square feet.

B. Grading Permits. A permit is required and shall be issued in accordance with Section 24.10.070 for all grading operations with the exception of the following:

1. Grading in an area, where in the opinion of the Director, there is no apparent danger, adverse drainage, or erosion effect on private/public property, or inspection is not necessary;

2. An excavation below finished grade for basements and footings of a building, retaining wall, or other structure authorized by a valid building permit. This shall not exempt any fill made with the material from such excavation nor exempt any excavation having an unsupported height greater than 5 feet after the completion of such structure.

3. Cemetery graves.

4. Refuse disposal sites controlled by other regulations.

5. Excavations for wells or tunnels.

6. Mining, quarrying, excavating, processing, stockpiling of rock, sand, gravel, aggregate, or clay where established and provided for by law provided such operations do not affect the lateral support or increase the stresses in or pressure upon any adjacent or contiguous property.

7. Exploratory excavations under the direction of soil (geotechnical) engineers or engineering geologists.

8. An excavation which

a. Is less than 2 feet in depth, or

b. Which does not create a cut slope greater than 5 feet in height and steeper than 1-1/2 horizontal to 1 vertical.

9. A fill less than 1 foot in depth, and placed on natural terrain with a slope flatter than 5 horizontal to 1 vertical, or less than 3 feet in depth, not intended to support structures, which does not obstruct a drainage course and which does not exceed 10 cubic yards on any one lot.

C. Tree cutting permit. A tree cutting permit is required for tree cutting (except Christmas trees) and root grubbing operations on slopes with gradients which, in whole or in part, exceed 25%. This regulation applies when more than five trees of six-inch diameter are to be cut or if the area to be cleared is greater than 2,500 square feet. This applies in all areas except those designated environmental zones under the provisions of Title 33. Tree cutting permits shall be issued in accordance with Section 24.10.070.

1. Plans and specifications showing the scope of proposed tree cutting operations, together with a geotechnical engineering report assessing the stability of the slope(s) after both tree felling and root grubbing operations shall be submitted to the Director along with the permit application.

2. Stripping of vegetation or other soil disturbance on the slopes shall be done in a manner which will minimize soil erosion and expose the smallest practical area at any one time. An erosion control and mitigation plan outlining how this is to be achieved and what erosion control measures are proposed to be implemented shall be submitted to the Director for approval.

3. The permit applicant shall also identify the owner’s agent who will be responsible for ensuring compliance with these requirements.

D. Permits required under this Chapter shall be obtained before the commencement of any tree cutting, root grubbing or soil disturbance takes place.

A. " Approval" shall mean a written engineering or geological opinion concerning the progress and completion of the work.

B. "As graded" is the surface conditions exposed on completion of grading.

C. "Bedrock" is in-place solid rock.

D. "Bench" is a relatively level step excavated into earth material on which fill is to be placed.

E. "Borrow" is earth material acquired from an off-site location for use in grading on a site.

F. "Civil engineer" shall mean a professional engineer registered in the State to practice in the field of civil works.

G. "Civil engineering" shall mean the application of the knowledge of the forces of nature, principles of mechanics, and the properties of materials to the evaluation, design, and construction of civil works for the beneficial uses of mankind.

H. "Clearing" is the cutting or removal of vegetation which results in exposing any bare soil.

I. "Compaction" is the densification of a fill by mechanical means.

J. "Earth material" is any rock, natural soil, or fill and/or any combination thereof.

K. "Engineering geologist" shall mean a geologist experienced and knowledgeable in engineering geology and registered as an engineering geologist in the State of Oregon.

L. "Engineering geology" shall mean the application of geologic knowledge and principles in the investigation and evaluation of naturally occurring rock and soil for use in the design of civil works.

M. "Erosion" is the wearing away of the ground surface as a result of the movement of wind, water, and/or ice.

N. "Excavation" is the mechanical removal of earth material.

O. "Fill" is a deposit of earth material placed by artificial means.

P. "Geological hazard" shall mean a potential or apparent risk to persons or property because of geological or soil instability either existing at the time of construction or which would result from construction.

Q. "Grade" shall mean the vertical location of the ground surface.

R. "Existing grade" is the grade prior to grading.

S. "Rough grade" is the stage at which the grade approximately conforms to the approved plan.

T. "Finish grade" is the final grade of the site which conforms to the approved plan.

U. "Grading" is any excavating or filling or combination thereof.

V. "Key" is a designed compacted fill placed in a trench excavated in earth material beneath the toe of a proposed fill slope.

W. "Site" is any lot or parcel of land or contiguous combination thereof, under the same ownership, where grading is performed or permitted.

X. "Slope" is an inclined ground surface the inclination of which is expressed as a ratio of horizontal distance to vertical distance.

Y. "Soil" is naturally occurring surficial deposits overlying bedrock.

Z. "Soil (Geotechnical) engineer" shall mean a civil engineer competent by education, training, and experience in the practice of soil engineering.

AA. "Soil (Geotechnical) engineering" shall mean the application of the principles of soil mechanics in the investigation, evaluation, and design of civil works involving the use of earth materials and the inspection and testing of the construction thereof.

BB. "Terrace" is a relatively level step constructed in the face of a graded slope surface for drainage and maintenance purposes.

A. Plans shall be drawn to scale upon substantial paper or cloth and shall be of sufficient clarity to indicate the nature and extent of the work proposed and show in detail that they will conform to the provisions of this Title and all relevant laws, ordinances, rules, and regulations. The first sheet of each set of plans shall give the location of the work and the name and address of the owner and the person by whom they were prepared.

The plans shall include the following information.

1. General vicinity of the proposed site.

2. Property limits and accurate contours of existing ground and details of terrain and area drainage for the site and surrounding area.

3. Limiting dimensions, elevations, or finish contours to be achieved by the grading and the proposed drainage channels and related construction.

4. Detailed schedule of when each portion of the site is to be graded; how long the soil is to be exposed; and when the area is to be covered with buildings, paving, new vegetation or temporary erosion control measures.

5. Detailed plans of all surface and subsurface drainage devices, walls, cribbing, dams, and other protective devices to be constructed with, or as a part of, the proposed work together with a map showing the drainage area and the estimated runoff of the area served by any drains.

6. Location of any buildings or structures on the property where the work is to be performed and the location of any buildings or structures on land of adjacent owners which are within 15 feet of the property or which may be affected by the proposed grading operations.

7. Specifications shall contain information covering construction and material requirements.

8. Civil engineering report. The civil engineering report, when required by the Director, shall include hydrological calculations of runoff and the existing or required safe storm drainage capacity outlet of channels both on site and off site, and 1 in 100 year flood elevations for any adjacent watercourse. The report shall include recommendations for stormwater control and disposal.

9. Soil (Geotechnical) engineering report. The soil engineering report, when required by the Director, shall include data regarding the nature, distribution, and strength of existing soils, design criteria, and conclusions and recommendations applicable to the proposed development. The report shall include recommendation for subdrainage, and for groundwater control and disposal. Recommendations included in the report and approved by the Director shall be incorporated in the plans and specifications. For single family residences, a surface reconnaissance and stability questionnaire may be substituted for a formal soils report at the discretion of the Director.

10. Engineering geology report. The engineering geology report, when required by the Director, shall include an adequate description of the geology of the site, and conclusions and recommendations regarding the effect of geologic conditions on the proposed development and site(s) to be developed.

Recommendations included in the report and approved by the Director shall be incorporated in the grading plans and specifications.

B. Issuance. Section 24.10.070 is applicable to grading permits. The Director may require that:

1. The amount of the site exposed during any one period of time be limited; and

2. Grading work be scheduled to avoid weather periods or avoid critical habitat use periods for areas existing on, or adjacent to, the development site.

Subsequent to the issuance of the grading permit, the Director may require that grading operations and project designs be modified if delays occur which can result in weather generated problems not considered at the time the permit was issued.

In lieu of a surety bond the applicant may file a cash bond or instrument of credit with the Director in an amount equal to that which would be required in the surety bond.

B. Slope. The slope of cut surfaces shall be no steeper than is safe for the intended use. Cut slopes shall be no steeper than 2 horizontal to 1 vertical.

C. Drainage and terracing. Drainage and terracing shall be provided as required by Section 24.70.100.

In the absence of an approved soil engineering report these provisions may be waived for minor fills not intended to support structures. Such fills shall be subject to review at the discretion of the Director.

B. Ground preparation. The ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, top-soil, and other unsuitable materials scarifying to provide a bond with the new fill, and where slopes are steeper than 5 to 1, and the height greater than 5 feet, by benching into competent material or sound bedrock as determined by the soils engineer. The bench under the toe of a fill on a slope steeper than 5 to 1 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. Where fill is to be placed over a cut the bench under the toe of a fill shall be at least 10 feet wide but the cut must be made before placing fill and approved by the soils engineer and engineering geologist as a suitable foundation for fill. Unsuitable soil is soil which in the opinion of the Director or the civil engineer or the soils engineer or the engineering geologist, is not competent to support either soil or fill, to support structures or to satisfactorily perform the other functions for which the soil is intended.

C. Fill material. Only permitted material free from tree stumps, detrimental amounts of organic matter, trash, garbage, sod, peat, and similar materials shall be used. Rocks larger than 6 inches in greatest dimension shall not be used unless the method of placement is properly devised, continuously inspected, and approved by the Director.

The following shall also apply:

1. Rock sizes greater than 6 inches in maximum dimension shall be 10 feet or more below grade, measured vertically.

2. Rocks shall be placed so as to assure filling all voids with fines. Topsoil may be used in the top 12-inch surface layer to aid in planting and landscaping.

D. Compaction of fill. All fills shall be compacted to a minimum relative dry density of 90 percent as determined in accordance with ASTM Standard D-1557-78. Field density verification shall be determined in accordance with ASTM Standard D-1556-82 or equivalent and must be submitted for any fill 12 inches or more in depth where such fill may support the foundation for a structure. A higher relative dry density, or additional compaction tests, or both, may be required at any time by the Director.

E. Fill slope. The slope of fill surfaces shall be no steeper than is safe for the intended use. Fill slopes shall be no steeper than 2 horizontal to 1 vertical.

F. Drainage and terracing. Drainage and terracing shall be provided and the area above fill slopes and the surfaces of terraces shall be graded and paved as required by Section 24.70.100.

B. Grading designation. All grading in excess of 5,000 cubic yards shall be performed in accordance with the approved grading plan prepared by a civil engineer and shall be designated as "engineered grading." Grading involving less than 5,000 cubic yards may also be designated as "engineered grading" by the Director if the grading will

1. support a building or structure of a permanent nature;

2. support other engineering works such as, but not limited to, tanks, towers, machinery, retaining wall, and paving;

3. be deemed a potential hazard under Section 24.70.030. The permittee with the approval of the Director may also choose to have the grading performed as "engineered grading." Otherwise, the grading shall be designated as "regular grading."

C. Engineered grading requirements. For engineered grading, it shall be the responsibility of the civil engineer who prepares the approved grading plan to incorporate all recommendations from the soil engineering and engineering geology reports into the grading plan. He shall also be responsible for the professional inspection and approval of the grading within his area of technical specialty. This responsibility shall include, but need not be limited to, inspection and approval as to the establishment of line, grade, and drainage of the development area. The civil engineer shall act as the coordinating agent in the event that need arises for liaison between the other professionals, the contractor, and the Director. The civil engineer shall also be responsible for the preparation of revised plans and the submission of as-graded grading plans upon completion of the work. The grading contractor shall submit in a form prescribed by the Director a statement of compliance to said as-graded plan.

Soil engineering and engineering geology reports shall be required as specified in Section 24.70.050. During grading all necessary reports, compaction data, and soil engineering and engineering geology recommendations shall be submitted to the civil engineer and the Director by the soil engineer and the engineering geologist. The soil engineer’s area of responsibility shall include, but need not be limited to, the professional inspection and approval concerning the preparation of ground to receive fills, testing for required compaction, stability of all finish slopes, and the design of buttress fills, where required, incorporating data supplied by the engineering geologist.

The engineering geologist’s area of responsibility shall include, but need not be limited to, professional inspection and approval of the adequacy of natural ground for receiving fills and the stability of cut slopes with respect to geological matters, and the need for subdrains or other ground water drainage devices. He shall report his findings to the soil engineer and the civil engineer for engineering analysis.

The Director shall inspect the project at the various stages of work requiring approval and at more frequent intervals necessary to determine that adequate control is being exercised by the professional consultants.

D. Regular grading requirements. The Director may require inspection and testing by an approved testing agency. The testing agency’s responsibility shall include, but need not be limited to, approval concerning the inspection of cleared areas and benches to receive fill, and the compaction of fills. When the Director has cause to believe that geological factors may be involved the grading operation will be required to conform to "engineered grading" requirements.

E. Notification of noncompliance. If, in the course of fulfilling their responsibility under this Chapter, the civil engineer, the soil engineer, the engineering geologist, or the testing agency finds that the work is not being done in conformity with this Chapter or the approved grading plans, the discrepancies shall be reported immediately in writing to the person in charge of the grading work and to the Director. Recommendations for corrective measures, if necessary, shall be submitted.

F. Transfer of responsibility for approval. If the civil engineer, the soil engineer, the engineering geologist, or the testing agency of record are changed during the course of the work, the work shall be stopped until the replacement has agreed to accept the responsibility within the area of their technical competence for approval upon completion of the work.

1. An as-graded grading plan prepared by the civil engineer including original ground surface elevations, as-graded ground surface elevations, lot drainage patterns, and locations and elevations of all surface and sub-surface drainage facilities. He shall provide approval that the work was done in accordance with the final approved grading plan.

2. A Soil Grading Report prepared by the soil engineer including locations and elevations of field density tests, summaries of field and laboratory tests and other substantiating data and comments on any changes made during grading and their effect on the recommendations made in the soil engineering investigation report. He shall provide approval as to the adequacy of the site for the intended use.

3. A Geological Grading Report prepared by the engineering geologist including a final description of the geology of the site including any new information disclosed during the grading and the effect of same on recommendations incorporated in the approved grading plan. He shall provide approval as to the adequacy of the site for the intended use as affected by geological factors.

B. Notification of completion. The permittee or his agent shall notify the Director when the grading operation is ready for final inspection. Final approval shall not be given until all work including installation of all drainage facilities and their protective devices and all erosion control measures have been completed in accordance with the final approved grading plan and the required reports have been submitted.