Applications for activities that are subject to provisions of this chapter are divided into the following categories based upon the level of site disturbance and impervious surfaces:
A. Basic Plan: The landowner shall provide a completed stormwater checklist on a form provided by the city, ensuring compliance with performance standards, for the following:
1. New construction, additions or modifications to existing structures, fill, excavation, or development in which all the following criteria are met:
a. Not within three hundred feet (300') of any surface water, shown on the National Hydrography Dataset or by actual survey.
b. Property has a slope of less than eight percent (8%).
c. New impervious surface created by the construction does not exceed one thousand (1,000) square feet.
d. Area of land-disturbing activities created by construction does not exceed five thousand (5,000) square feet.
e. The city engineer may require parcels adjacent to a new or existing road with a road profile slope of seven percent (7%) or greater to comply with a Minor Plan.
f. Development does not result in more than fifty (50) cubic yards of fill or excavated material.
g. Development does not result in more than five thousand (5,000) square feet of disturbed area.
h. Development does not change grade by more than four feet (4') in height.
B. Minor Plan: A sedimentation and erosion control plan shall be submitted by the property owner and approved by the city prior to the commencement of any construction, development, or site disturbance for low-impact developments that meet the following criteria:
1. Excavation or fill between fifty (50) cubic yards and two hundred fifty (250) cubic yards of material.
2. Construction or reconstruction of structures, paving, or other activities between one thousand (1,000) square feet and three thousand (3,000) square feet of new impervious surface.
3. Land-disturbing activities between five thousand (5,000) square feet of disturbed area and ten thousand (10,000) square feet of disturbed area.
4. Construction or development adjacent to a new or existing road with a roadway profile slope of seven percent (7%) or greater.
5. Excavation, fill, construction, reconstruction, or land disturbing activities on sites that are within three hundred feet (300') of any surface water, shown on the National Hydrography Dataset or by actual survey, or on a slope of eight percent (8%) or greater and do not exceed any of the following:
a. One thousand (1,000) square feet of new impervious surface.
b. Five thousand (5,000) square feet of land-disturbing activities.
c. Fifty (50) cubic yards of fill or excavated material.
d. A four-foot (4') change in grade.
6. The city engineer may require the plans for more complex sites that meet the requirements of a Minor Plan be sealed by a design professional licensed in the State of Idaho.
C. Major Plan: A Stormwater Management Plan shall be submitted and sealed by a design professional licensed in the State of Idaho and approved by the city prior to the commencement of any construction, development, or site disturbance for developments that meet the following criteria:
1. Fill or excavation that will result in two hundred fifty (250) cubic yards or more of material.
2. Construction or reconstruction of structures, paving, or other activities that will create more than three thousand (3,000) square feet of new impervious surface.
3. Land-disturbing activities that will result in ten thousand (10,000) square feet of disturbed area or more.
4. Excavation, fill, construction, reconstruction, or land disturbing activities on sites that are within three hundred feet (300') of any surface water, shown on the National Hydrography Dataset or by actual survey, or on a slope of eight percent (8%) or greater slope that exceed:
a. One thousand (1,000) square feet of new impervious surface.
b. Five thousand (5,000) square feet of land-disturbing activities.
c. Fifty (50) cubic yards of fill or excavated material.
d. A four-foot (4') change in grade.
D. Subdivision Plan:
1. All new subdivisions and phases of existing subdivisions shall provide a preliminary stormwater management plan at the time of preliminary plat application, unless otherwise provided herein. The final stormwater management plan, consistent with this chapter shall be filed with the subdivision construction plans, prior to any site disturbance, in accord with the subdivision regulations of Title 11 of this code.
2. The requirements of the United States Clean Water Act (33 U.S.C. § 1251) and Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) Program and regulations shall be met. Per the EPA, all acreages of all phases of a development are to be counted in the determination on the need for a Notice of Intent, SWPPP and other EPA NPDES and U.S. Army Corps Section 404 permit requirements.
3. Development of lots shall be in accord with the approved subdivision stormwater management plan. At the time of building permit application, the landowner shall provide plans indicating how the lot will be developed to meet the requirements of the approved plan.
4. For subdivisions that do not have approved stormwater management plans, lot development is subject to the "Applicability" section of this chapter and the applicable requirements of this chapter.
E. Application Contents: Applications shall contain the following minimum information:
1. Basic Plan: Completion of the city checklist.
2. Minor Plan (Sedimentation and Erosion Control Plan):
a. A project site plan showing the limits of proposed construction, location of proposed and existing structures, walkways, driveways, roads, surface water, wetlands, vegetative coverage, any proposed soil stockpiles, drainage patterns, and existing or proposed temporary and permanent sedimentation/erosion control and stormwater features.
b. A summary of the proposed construction project, including methods to stabilize soils and control sedimentation during and after construction, erosion control features, use of existing and proposed vegetation.
c. Proposed construction schedule.
d. Maintenance and monitoring plans, to include requirements for inspection before, during, and after storm events.
3. Major Plan (Stormwater Management Plan):
a. The items required for a preliminary stormwater management plan, listed at subsection E.2. of this section.
b. Construction-quality drawings of all physical features of a proposed stormwater management system, including dimensions and capacities for all conveyances, retention basins, swales, and other features designed for collection, treatment, and infiltration of stormwater runoff.
c. A proposed construction schedule for the stormwater management system.
d. A sedimentation and erosion control plan.
e. A proposed system of maintenance and inspection schedules for the stormwater management system, designating specifically any portions which are to be conveyed to a group, association, or political subdivision for maintenance.
4. Subdivision Preliminary Stormwater Management Plan Contents:
a. The stamp and/or signature of the design professional who prepared the plan.
b. A project site plan showing the entire area covered by the application, any construction sites, proposed or existing lot lines, existing drainage patterns, surface water, proposed roads, proposed stormwater easements, proposed stockpile areas, sufficient topographic information to shown contours of the land, constraining environmental conditions and areas to be covered by impervious surfaces at completion of the project.
c. A project summary describing site characteristics, soil types, vegetative coverage; slopes, calculations of the estimated impervious surface coverage, design storm yield for the site; and proposed stormwater and erosion control features. (Ord. 170, 11-12-2020)