The provisions of this Chapter regulate clearing, grading and earthwork construction on private property. Tree removal, whether associated with clearing, grading, earthwork construction or conducted separately is regulated pursuant to Title 11, Trees. Erosion control is regulated by Title 10.

1. Permits for clearing, grading, and retaining walls are required as specified in this Section.  Where a specific activity does not require a clearing or grading permit, a separate tree permit may still be required, as specified in Title 11 Trees.  Where a clearing or grading development permit shows trees to be removed and has been reviewed and approved by the City, a separate tree permit is not required in conjunction with the clearing or grading permit.  An erosion, sediment and pollutant control plan if required by Title 10 must be submitted with clearing or grading permit applications.  Applicants for permits made in conjunction with land divisions will be responsible for all clearing, grading, tree removal and erosion control within the land division, even where a specific activity is exempt from an individual permit.
2. A.  Clearing Permits.  A permit is required and will be issued in accordance with Section 24.10.070 for clearing activities in the following areas:
   1. 1.  The Tualatin River sub-basins, Johnson Creek Basin Plan District, environmental zones, greenway zones, or natural resource management plans; or
   2. 2.  Property larger than five acres.  Except that no permit is required for clearing an area less than 5,000 square feet.
3. B.  Grading permits.  A permit is required and will be issued in accordance with Section 24.10.070 for all grading operations with the exception of the following:
   1. 1.  Grading in an area where, in the opinion of the City Administrator, there is no apparent danger, adverse drainage, or erosion effect on private/public property, or inspection is not necessary;
   2. 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 does 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. 3.  Cemetery graves.
   4. 4.  Refuse disposal sites controlled by other regulations.
   5. 5.  Excavations for wells or tunnels.
   6. 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. 7.  Exploratory excavations under the direction of soil (geotechnical) engineers or engineering geologists.
   8. 8.  An excavation that
      1. a.  Is less than 2 feet in depth, or
      2. b.  Does not create a cut slope greater than 5 feet in height and steeper than 1‑1/2 horizontal to 1 vertical.
   9. 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, that does not obstruct a drainage course and that does not exceed 10 cubic yards on any one lot.
4. C.  Retaining walls. A permit is required and will be issued in accordance with Section 24.10.070 for all retaining walls over 4 feet (1219 mm) in height measured from the bottom of the footing to the top of the wall, and for retaining walls supporting a surcharge.
5. D.  Tree removal. Removal of trees six inches and larger in diameter will be reviewed with the clearing or grading permits as part of the Tree Plan review pursuant to Title 11. When removing 5 or more trees on a site with an average slope of at least 20 percent, applicants must provide a geotechnical engineering report that assesses the stability of the site after tree felling and root grubbing operations.
6. E.  Permits required under this Chapter must be obtained before the commencement of any tree removal, root grubbing or soil disturbance takes place.

The City Administrator may determine that any clearing, grading, retaining wall, or geologic condition on private property has or may become a hazard to life and limb, or endanger property, or cause erosion, or adversely affect drainage or the safety, use or stability of a public way or drainage channel. Upon receipt of notice in writing from the City Administrator, the owner must mitigate the hazard and be in conformity with the requirements of this Title. The City Administrator may require that plans and specifications and engineering reports be prepared in compliance with this Chapter.

1. The definitions contained in this Section relate to excavation and grading work only as outlined in this Chapter.
2. A.  Approval means a written engineering or geological opinion concerning the progress and completion of the work.
3. B.  As graded is the surface conditions exposed on completion of grading.
4. C.  Bedrock is in‑place solid rock.
5. D.  Bench is a relatively level step excavated into earth material on which fill is to be placed.
6. E.  Borrow is earth material acquired from an off‑site location for use in grading on a site.
7. F.  Civil engineer means a professional engineer registered in the State to practice in the field of civil works.
8. G.  Civil engineering means 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.
9. H.  Clearing is the cutting or removal of vegetation that results in exposing any bare soil.
10. I.  Compaction is the densification of a fill by mechanical means.
11. J.  Earth material is any rock, natural soil, or fill and/or any combination thereof.
12. K.  Engineering geologist means a geologist experienced and knowledgeable in engineering geology and registered as an engineering geologist in the State of Oregon.
13. L.  Engineering geology means 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.
14. M.  Erosion is the wearing away of the ground surface as a result of the movement of wind, water, and/or ice.
15. N.  Excavation is the mechanical removal of earth material.
16. O.  Fill is a deposit of earth material placed by artificial means.
17. P.  Geological hazard means a potential or apparent risk to persons or property because of geological or soil instability either existing at the time of construction or that would result from construction.
18. Q.  Grade means the vertical location of the ground surface.
19. R.  Existing grade is the grade prior to grading.
20. S.  Rough grade is the stage at which the grade approximately conforms to the approved plan.
21. T.  Finish grade is the final grade of the site that conforms to the approved plan.
22. U. Grading is any excavating or filling or combination thereof.
23. V.  Key is a designed compacted fill placed in a trench excavated in earth material beneath the toe of a proposed fill slope.
24. W.  Retaining wall is a structure that provides lateral support for a mass of soil or fluid and other imposed loads.
25. X.  Site is any lot or parcel of land or contiguous combination thereof, under the same ownership, where grading is performed or permitted.
26. Y.  Slope is an inclined ground surface the inclination of which is expressed as a ratio of horizontal distance to vertical distance.
27. Z.  Soil is naturally occurring surficial deposits overlying bedrock.
28. AA.  Soil (Geotechnical) engineer means a civil engineer competent by education, training, and experience in the practice of soil engineering.
29. BB.  Soil (Geotechnical) engineering means 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.
30. CC.  Terrace is a relatively level step constructed in the face of a graded slope surface for drainage and maintenance purposes.

1. Plans and specifications must be submitted in accordance with Section 24.10.070 and in addition must comply with the following:
2. A.  Plans must be drawn to scale upon substantial paper or cloth and must 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 must give the location of the work and the name and address of the owner and the person by whom they were prepared.
3. The plans must include the following information.
   1. 1.  General vicinity of the proposed site.
   2. 2.  Property limits and accurate contours of existing ground and details of terrain and area drainage for the site and surrounding area.
   3. 3.  Limiting dimensions, elevations, or finish contours to be achieved by the grading and the proposed drainage channels and related construction.
   4. 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. 5.  Detailed plans of all surface and subsurface drainage devices, walls, retaining 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. 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 or trees in the adjacent rights-of-way that are within 15 feet of the property or that may be affected by the proposed grading operations.
   7. 7.  Specifications must contain information covering construction and material requirements.
   8. 8.  Civil engineering report.  The civil engineering report, when required by the City Administrator, must 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 must include recommendations for stormwater control and disposal.
   9. 9.  Soil (Geotechnical) engineering report.  The soil engineering report, when required by the City Administrator, must include data regarding the nature, distribution, and strength of existing soils, design criteria, and conclusions and recommendations applicable to the proposed development.  The report must include recommendation for subdrainage, and for groundwater control and disposal.  Recommendations included in the report and approved by the City Administrator must 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 City Administrator.
   10. 10.  Engineering geology report.  The engineering geology report, when required by the City Administrator, must 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.
   11. Recommendations included in the report and approved by the City Administrator must be incorporated in the grading plans and specifications.
4. B.  Issuance.  Section 24.10.070 is applicable to grading permits.  The City Administrator may require that:
   1. 1.  The amount of the site exposed during any one period of time be limited; and
   2. 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.
5. Subsequent to the issuance of the grading permit, the City Administrator may require that grading operations and project designs be modified if delays occur that can result in weather generated problems not considered at the time the permit was issued.

1. The City Administrator may require bonds in such form and amounts as may be deemed necessary to assure that the work, if not completed in accordance with the approved plans and specifications, will be corrected to eliminate hazardous conditions.
2. In lieu of a surety bond, the applicant may file a cash bond or instrument of credit with the City Administrator in an amount equal to that which would be required in the surety bond.

1. A. General. Unless otherwise recommended in the approved soil engineering and/or engineering geology reports, cuts must conform to the provisions of this Section.
2. B. Slope. The slope of cut surfaces may be no steeper than is safe for the intended use. Cut slopes may be no steeper than 2 horizontal to 1 vertical.
3. C. Drainage and terracing. Drainage and terracing must be provided as required by Section 24.70.100.

1. A. General. Unless otherwise recommended in the approved soil engineering report, fills must conform to the provisions of this Section.
2. In the absence of an approved soil engineering report these provisions may be waived for minor fills not intended to support structures. Such fills are subject to review at the discretion of the City Administrator.
3. B. Ground preparation. The ground surface must 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 must be at least 10 feet wide. The area beyond the toe of fill must be sloped for sheet overflow or a paved drain must be provided. Where fill is to be placed over a cut the bench under the toe of a fill must 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 that, 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.
4. C. Fill material. Only permitted material free from tree stumps, detrimental amounts of organic matter, trash, garbage, sod, peat, and similar materials may be used. Rocks larger than 6 inches in greatest dimension may not be used unless the method of placement is properly devised, continuously inspected, and approved by the City Administrator.
5. The following also apply:
   1. 1. Rock sizes greater than 6 inches in maximum dimension must be 10 feet or more below grade, measured vertically.
   2. 2. Rocks must 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.
6. D. Compaction of fill. All fills must be compacted to a minimum relative dry density of 90 percent as determined in accordance with ASTM Standard D-1557-78. Field density verification must 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 City Administrator.
7. E. Fill slope. The slope of fill surfaces may be no steeper than is safe for the intended use. Fill slopes may be no steeper than 2 horizontal to 1 vertical.
8. F. Drainage and terracing. Drainage and terracing must be provided and the area above fill slopes and the surfaces of terraces must be graded and paved as required by Section 24.70.100.

1. A.  Retaining walls not regulated by the Oregon Residential Specialty Code or the Oregon Structural Specialty Code must be designed in accordance with ASCE 7-16 and this section.
2. B.  Soil loads must be determined in accordance with ASCE 7-16. Retaining walls in which horizontal movement is restricted at the top must be designed for at-rest pressure.  Retaining walls free to move and rotate at the top must be permitted to be designed for active pressure.  Lateral pressure from surcharge loads must be added to the lateral earth pressure load. Lateral pressure must be increased if soils at the site are expansive or the retaining wall will support an ascending slope.  Retaining walls must be designed to support the weight of the full hydrostatic pressure of undrained backfill unless a drainage system is installed.
3. C.  Retaining walls supporting more than 6 feet of backfill height, measured from the base of the footing to the top of the wall, must incorporate an additional dynamic seismic lateral earth pressure. When the Monobe-okabe method is used to calculate the active dynamic seismic lateral earth pressure, a horizontal acceleration coefficient equal to or greater than one-half (0.5) the design peak horizontal ground acceleration must be used.
4. D.  Retaining walls must be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift.  Retaining walls must be designed to resist the lateral action of soil to produce sliding and overturning with a minimum safety factor of 1.5 in each case. The load combinations of ASCE 7-16 do not apply to this requirement.  Instead, the design must be based on 0.7 times nominal earth-quake loads, 1.0 times other nominal loads, and investigation with one or more of the variable loads set to zero.  The safety factor against lateral sliding must be taken as the available soil resistance at the base of the retaining wall foundation divided by the net lateral force applied to the retaining wall.
5. Exception: Where earthquake loads are included, the minimum safety factor for retaining wall sliding and overturning is 1.1.

1. A. General. The setbacks and other restrictions specified by this Section are minimal and may be increased by the City Administrator, or by the recommendation of the civil engineer, soils engineer, or engineering geologist, if necessary for safety and stability or to prevent damage of adjacent properties from deposition or erosion or to provide access for slope maintenance and drainage. Retaining walls may be used to reduce the required setbacks when approved by the City Administrator.
2. B. Setbacks from property lines. The tops of cuts and toes of fill slopes must be set back from the outer boundaries of the permit area, including slope right areas and easements, in accordance with Figure No. 2 and Table No. 24.70-C at the end of this Chapter.
3. C. Design standards for setbacks. Setbacks between graded slopes (cut or fill) and structures must be provided in accordance with Figure No. 3 and Table No. 24-70-C at the end of this Chapter. 

1. A. General. Unless otherwise indicated on the approved grading plan, drainage facilities and terracing must conform to the provisions of this Section.
2. B. Terrace. Terraces at least 6 feet in width must be established at not more than 30-foot vertical intervals on all cut or fill slopes to control surface drainage and debris except that where only one terrace is required, it must be at mid-height. For cut or fill slopes greater than 60 feet and up to 120 feet in vertical height one terrace at approximately mid-height must be 12 feet in width. Terrace widths and spacing for cut and fill slopes greater than 120 feet in height must be designed by the civil engineer and approved by the City Administrator. Suitable access must be provided to permit proper cleaning and maintenance.
3. A single run of swale or ditch may not collect runoff from a tributary area exceeding 13,500 square feet (projected) without discharging into a downdrain.
4. C. Subsurface drainage. Cut and fill slopes must be provided with subdrainage as necessary for stability. Adequate culverts must be laid under all fills placed in natural watercourses and along the flow line of any tributary branches in such a manner that the hydraulic characteristics of the stream are not adversely altered. In addition, subdrainage must be installed if active or potential springs or seeps are covered by the fill. All culverts/subdrainage must be installed after the suitable subgrade preparation. Design details of culverts/subdrainage must be shown on each plan and be subject to the approval of the City Administrator and of other government/private agencies as may be required.
5. A subdrain system must be provided for embedded foundation/ retaining walls and floor slabs where ground water or seepage has a potential to affect the performance of the structure. The plans must indicate
   1. 1. subdrainage details with appropriate specifications,
   2. 2. location of footing subdrain/discharge lines and,
   3. 3. method of disposal.
6. In lieu of above, walls/floors may be waterproofed and designed to resist hydrostatic pressure.
7. D. Disposal. All drainage facilities must be designed to carry waters to the nearest practicable drainageway or approved stormwater management facility, as approved by the City Administrator and/or other appropriate jurisdiction as a safe place to deposit such waters. Erosion of ground in the area of discharge must be prevented by installation of non-erosive downdrains or other devices.
8. Building pads must have a drainage gradient of 2 percent toward approved drainage facilities, unless waived by the City Administrator.
9. Exception: The gradient from the building pad may be 1 percent if all of the following conditions exist throughout the permit area:
   1. 1. No proposed fills are greater than 10 feet in maximum depth.
   2. 2. No proposed finish cut or fill slope faces have a vertical line in excess of 10 feet.
   3. 3. No existing slope faces that have a slope face steeper than 10 horizontal to 1 vertical have a vertical height in excess of 10 feet.
10. E. Interceptor drains. Paved interceptor drains must be installed along the top of all cut slopes where the tributary drainage area above slopes towards the cut and has a drainage path greater than 40 feet measured horizontally. Interceptor drains must be paved with a minimum of 3 inches of concrete or gunite and reinforced. They must have a minimum depth of 12 inches and a minimum paved width of 30 inches measured horizontally across the drain. The slope of the drain must be approved by the City Administrator.

1. A.  General.  All grading operations for which a permit is required is subject to inspection by the City Administrator.  When required by the City Administrator, special inspection of grading operations and special testing must be performed in accordance with the provisions of Subsection 24.70.120 C.
2. B.  Grading designation.  All grading in excess of 5,000 cubic yards must be performed in accordance with the approved grading plan prepared by a civil engineer and must be designated as “engineered grading.”  Grading involving less than 5,000 cubic yards may also be designated as “engineered grading” by the City Administrator if the grading will:
   1. 1.  support a building or structure of a permanent nature;
   2. 2.  support other engineering works such as, but not limited to, tanks, towers, machinery, retaining wall, and paving;
   3. 3.  be deemed a potential hazard under Section 24.70.030.  The permittee with the approval of the City Administrator may also choose to have the grading performed as “engineered grading.”  Otherwise, the grading must be designated as “regular grading.”
3. C.  Engineered grading requirements.  For engineered grading, it is 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.  The civil engineer is also responsible for the professional inspection and approval of the grading within the civil engineer’s area of technical specialty.  This responsibility includes, 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 must act as the coordinating agent in the event that need arises for liaison between the other professionals, the contractor, and the City Administrator.  The civil engineer will 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 must submit in a form prescribed by the City Administrator a statement of compliance to said as-graded plan.
4. Soil engineering and engineering geology reports will be required as specified in Section 24.70.050.  During grading all necessary reports, compaction data, and soil engineering and engineering geology recommendations must be submitted to the civil engineer and the City Administrator by the soil engineer and the engineering geologist.  The soil engineer’s area of responsibility includes, 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.
5. The engineering geologist’s area of responsibility includes, 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.  The engineering geologist must report the findings to the soil engineer and the civil engineer for engineering analysis.
6. The City Administrator may 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.
7. D.  Regular grading requirements.  The City Administrator may require inspection and testing by an approved testing agency.  The testing agency’s responsibility includes, 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 City Administrator has cause to believe that geological factors may be involved the grading operation will be required to conform to “engineered grading” requirements.
8. 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 must be reported immediately in writing to the person in charge of the grading work and to the City Administrator.  Recommendations for corrective measures, if necessary, must be submitted.
9. 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 must 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. A.  Final reports.  Upon completion of the rough grading work and that final completion of the work the Building Official may require the following reports and drawings and supplements to it:
   1. 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.  The civil engineer must provide approval that the work was done in accordance with the final approved grading plan.
   2. 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.  The soil engineer must provide approval as to the adequacy of the site for the intended use.
   3. 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.  The engineering geologist must provide approval as to the adequacy of the site for the intended use as affected by geological factors.
2. B.  Notification of completion.  The permittee or their agent must notify the City Administrator when the grading operation is ready for final inspection.  Final approval will 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.