40.380.030    Exemptions and Exceptions

A.    Exemptions shall be granted for the following conditions:

1.    Commercial agricultural, and forest practices regulated under Title 222 WAC, except for Class IV general forest practices that are conversions from timber land to other uses, are exempt from the provisions of the minimum requirements. All other new development is subject to the minimum requirements;

2.    Normal landscape maintenance activities and gardening;

3.    Land-disturbing activities of less than one (1) acre that do not result in additional or replaced impervious surface are exempt from Sections 40.380.040(B) and (C);

4.    School modulars or portables are exempt from Sections 40.380.040(B) and (C), provided the buildings utilize roof downspout systems to infiltrate roof runoff. A final stormwater design that addresses disposal of stormwater shall be required;

5.    The construction of single-family homes, duplexes, and their accessory structures may be exempted from Sections 40.380.040(B), (C), and (C)(4), provided the following conditions are met:

a.    The development site or parcel is included in an approved stormwater facility system meeting the requirements of this chapter,

b.    The system provides for detention or retention of runoff from residential lots, and

c.    An erosion control plan is prepared and implemented;

6.    The construction of single-family homes, and their normal appurtenances and accessory structures, on an existing lot within the rural area shall be exempt from Sections 40.380.040(B) and (C);

7.    Drainage projects that are not a part of a development activity or redevelopment under Section 40.380.040(B)(3) are exempt from Section 40.380.040(B) and the responsible official may waive all or parts of Sections 40.380.060 and 40.380.040(H) and (J) if the project meets the other appropriate parts of this chapter;

8.    Small residential projects that create less than two thousand (2,000) square feet of new impervious surface in urban areas and five thousand (5,000) square feet in rural areas, and infill projects that meet the eligibility requirements of Section 40.260.110(B)(1), that create less than five thousand (5,000) square feet of new impervious surface are exempt from Section 40.380.040(B) and (C). Houses that utilize roof downspout systems to infiltrate roof runoff may be deducted from area calculations. A final stormwater plan is required if stormwater is conveyed off-site. The submittal requirements (Section 40.380.060) for small residential projects are modified as follows:

a.    An abbreviated preliminary stormwater plan as outlined in Section 40.380.060(B) can be substituted for the preliminary stormwater plan,

b.    A Technical Information Report (Section 40.380.060(D)(4)) shall not be required. However, sufficient information and data shall be provided with the final stormwater plan to allow the responsible official to determine conformance with the applicable provisions of this section;

9.    Government Agency Projects. Development activities and drainage projects undertaken by governmental agencies are exempt from Section 40.380.040(J);

10.    A preliminary stormwater plan is not required when a development is already provided for in a previously approved plan;

11.    Agriculture. In this section, agricultural uses must occur on property that is either:

a.    Participating in a current use assessment classification for agricultural land pursuant to Chapter 84.34 RCW or is eligible for such current use assessment classification;

b.    Conducted under a farm management plan approved by Clark conservation district; or

c.    Conducted under a farm management plan that is approved by the Clark conservation district within two (2) years of the adoption of this section. The plan shall require site-specific management measures for minimizing non-point pollution from agricultural activities excluding runoff from existing buildings.

(Amended: Ord. 2006-11-15)

B.    Exceptions to the requirements of this section may be granted prior to permit approval and construction. An exception may be granted following a Type III process; provided, that a written finding of fact is adopted, that addresses the following:

1.    The exception provides for equivalent environmental protection and is in the overriding public interest; and that the objectives of safety, function, environmental protection and facility maintenance, based upon sound engineering, are fully met;

2.    That there are special physical circumstances or conditions affecting the property such that the strict application of these provisions would deprive the developer of all reasonable use of the parcel of land in question, and every effort to find creative ways to meet the intent of the requirements has been made;

3.    That the granting of the exception will not be detrimental to the public health and welfare, nor injurious to other properties in the vicinity and/or downstream, and to the quality of waters of the state; and

4.    The exception is the least possible exception that could be granted to comply with the intent of this section.

    Prior to commencing construction, the applicant must show that no sediment can be transported from the site. No degradation of the environment or drainage facilities may result from the proposed activity, even in the absence of BMPs. Criteria for approval are non-erodible soils, runoff discharges to a temporary infiltration device, or runoff discharges to an on-site closed depression.

C.    Other.

1.    Construction Tolerances. The responsible official may approve deviations of up to ten percent (10%) from an approved design using a Type I procedure upon findings that water quality, water quantity control, and maintainability are not affected.

a.    The responsible official may require the revision of a previously approved preliminary or final stormwater control plan using a Type II post-decision review whenever the developer proposes a modification to the previously approved activity that creates additional adverse impacts.