27.14.050 Stormwater Management Manual and review thresholds.
(1) Based on parcel size, nature of development, amount of land disturbing activity, plat requirements, or potential to significantly impact receiving waters, infrastructure, County roads, or adjoining properties, the County Engineer, or their designee may require an engineered drainage, erosion and sediment control plan regardless of the thresholds found below. The purpose of the engineered drainage, erosion, and sediment control plan is to ensure that the plan will work and also to receive an installed as designed letter from the Engineer.
(2) The Department of Community Development (DCD) Administrator or her designee will require land disturbing activity within the jurisdiction of critical areas to submit a drainage permit, unless both of the following conditions apply: (1) the DCD Administrator or her designee determines the project will not affect the critical area, and (2) the project falls below the thresholds found in CCC 27.14.060. These critical area requirements are currently in effect, and the only modifications to these requirements are that land development activity will be subject to the 2019 SWMMWW instead of the 1992 SWMMWW.
(3) Stormwater Management Manual within the Unincorporated County Urban Growth Area (UGA) Around the City of Port Angeles, Also Known as the Unincorporated Port Angeles UGA or UPAUGA. Within the UPAUGA, Clallam County adopts Ecology’s 2019 Stormwater Management Manual for Western Washington (“Ecology’s 2019 Stormwater Manual”) in its entirety (with no modifications).
(4) Stormwater Management Manual Within Unincorporated Clallam County Outside the UPAUGA. Outside of the UPAUGA, Ecology’s 2019 Stormwater Manual’s minimum requirements contained in Volume I, Section 3.4, are modified as provided in the table below. For certain proposed land development activities, Clallam County adopts and applies the Clallam County Small Project Drainage Manual as provided in the table below. The County may require the use of Ecology’s 2019 Stormwater Manual if conditions are not met under the Small Project Drainage Manual or the project requires an engineer under State law.
(5) Stormwater Management Requirements for New Development and Redevelopment Within Unincorporated Clallam County Outside of the UPAUGA.
Thresholds (Hard Surface/Land Disturbance) | Drainage Permit Required – Y/N? | Applicable Stormwater Manual | Minimum Requirements (MR) |
|---|---|---|---|
N/A | N | Subject to BMPs 5.11 and 5.12 of the 2019 Ecology Manual or Section 3.4 of the Clallam County Small Project Drainage Manual | N/A |
Thresholds (Hard Surface/Land Disturbance) | Drainage Permit Required – Y/N? | Applicable Stormwater Manual | Minimum Requirements (MR) |
|---|---|---|---|
< 400 sq. ft. of new plus replaced hard surface OR < 7,000 sq. ft. land disturbing activity | No, but construction stormwater best management practices are always required | N/A | MR 2 |
Between 400 and 5,000 sq. ft. of new plus replaced hard surface OR between 7,000 and 10,000 sq. ft. land disturbing activity | Yes | Clallam County Small Project Drainage Manual2 | MRs 1 – 5 |
≥ 5,000 sq. ft. of new plus replaced hard surface OR ≥ 10,000 sq. ft. land disturbing activity | Yes | Ecology’s 2019 Stormwater Manual | MRs 1 – 94; Engineered Plan required |
Thresholds (Hard Surface/Land Disturbance) | Drainage Permit Required – Y/N? | Applicable Stormwater Manual | Minimum Requirements (MR) |
|---|---|---|---|
< 400 sq. ft. of new plus replaced hard surface OR < 7,000 sq. ft. land disturbing activity OR < 1.5 acres of veg to lawn conversion, OR < 5 acres of veg to pasture | No, but construction stormwater best management practices are always required | N/A | MR 2 |
Between 400 and 3,000 sq. ft. of new plus replaced hard surface (requiring a building permit) | Yes | Clallam County Small Project Drainage Manual2 | MRs 1 – 5, Optional Flow Control determined by County Engineer3 |
Between 3,000 and 7,000 sq. ft. of new plus replaced hard surface OR between 7,000 and 12,000 sq. ft. land disturbing activity OR between 1.5 and 2 acres of veg to lawn conversion, OR between 5 and 7.5 acres of veg to pasture | Yes | Clallam County Small Project Drainage Manual2 | MRs 1 – 5 |
≥ 7,000 sq. ft. new plus replaced hard surface OR ≥ 12,000 sq. ft. land disturbing activity, OR ≥ 2 acres of veg to lawn conversion, OR ≥ 7.5 acres of veg to pasture conversion | Yes | Ecology’s 2019 Stormwater Manual | MRs 1 – 94; Engineered Plan required |
Thresholds (Hard Surface/Land Disturbance) | Drainage Permit Required – Y/N? | Applicable Stormwater Manual | Minimum Requirements (MR) |
|---|---|---|---|
< 2,000 sq. ft. of new plus replaced hard surface OR < 7,000 sq. ft. land disturbing activity | No, but construction stormwater best management practices are always required | N/A | MR 2 |
≥ 2,000 sq. ft. of new plus replaced hard surface OR ≥ 7,000 sq. ft. land disturbing activity | Yes | Ecology’s 2019 Stormwater Manual | Per Manual; Engineered Plan required |
Footnotes:
1Residential development is the construction of a single-family dwelling, duplex, townhome, accessory structures to such dwelling. Residential driveways meeting BMPs in Table 27.14.050(5)(A) are not counted in hard surface calculations for residential development.
2Applicants may elect to use the 2019 Ecology Stormwater Manual instead of the Clallam County Small Project Drainage Manual if they choose. If utilizing the 2019 Ecology Stormwater Manual, a civil or geotechnical engineer may be required to sign stormwater plans.
3For land development activity that would not require flow controls or meet full dispersion (BMP T5.30) requirements per the 2019 SMMWW, the County Engineer will determine optional flow control requirements through the Small Project Drainage Manual.
4MR 3 and MR 8 are usually N/A; MR 9 only applies if a stormwater facility is installed.