(Amended by Ordinance Nos. 165678, 168340 172209, 173532, 173979, 184522, 185448, 186053 and 188884, effective April 4, 2018.) 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 shall be submitted with clearing or grading permit applications. Applicants for permits made in conjunction with land divisions shall 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.
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. Retaining Walls. A permit is required and shall 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.
D. Tree Removal. Removal of trees six-inches and larger in diameter shall 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 shall provide a geotechnical engineering report that assesses the stability of the site after tree felling and root grubbing operations.
E. Permits required under this Chapter shall be obtained before the commencement of any tree removal, root grubbing or soil disturbance takes place.