The following performance standards are applicable to all design, construction, implementation, and maintenance of stormwater management systems pursuant to this chapter:
A. All activities subject to the requirements of this chapter shall be carried out in a manner that ensures that runoff of storm or other natural surface waters shall not be accelerated, concentrated, or otherwise conveyed beyond the exterior property lines or project boundaries of the project in question. Existing and/or proposed off site public street drainage shall be detained separately from the on site drainage. All stormwater facilities and BMPs required for the project must be constructed within the project boundary or property lines.
1. Exceptions: Runoff of storm or other surface waters may be conveyed beyond the exterior property lines or project boundaries if:
a. Done in accordance with the provisions of a joint stormwater management agreement approved in writing by the city; or
b. The downstream property received drainage prior to development. In this case, flow may not be concentrated onto downstream properties where sheet flow previously existed. In no event will there be a measurable increase in the peak rate of runoff from the site after development when compared with the runoff rate in the undeveloped state for a 25-year storm.
c. Runoff may be conveyed beyond property lines onto public rights of way where necessary to obtain site access via driveways, curb cuts or other access points.
B. Erosion, sediment, or discharge of pollutants, resulting from construction activities, which enter onto public property or private property not controlled by the permit holder, shall be eliminated to the maximum extent practicable unless otherwise permitted or exempted under this chapter.
C. All construction activity commenced pursuant to an approved stormwater management plan or site development permit must at all times comply with the conditions of the plan or permit. The permit holder is responsible for ensuring their contractor(s), subcontractor(s), utility trenching subcontractor(s), and all other persons entering the site abide by the conditions of the permit. The permit holder's signature or that of his authorized agent on the permit shall constitute an agreement by the permit holder to accept responsibility for meeting the conditions of the permit.
D. No construction activity shall take place without a valid stormwater management plan. If a permit has been suspended or revoked, or has expired, all work covered by the plan shall cease until a new plan is issued.
E. All necessary action shall be taken to minimize the depositing and tracking of mud, dirt, sand, gravel, rock or debris on or onto the public right of way. The owner of the site of the construction activity or the permit holder with respect to the construction site shall be responsible for any cleanup of the public rights of way or private property not under the permit holder's control necessitated from any tracking or depositing of mud, dirt, sand, gravel, rock or debris, or shall reimburse the city for any expenses incurred by the city to effectuate the cleanup. At a minimum, all public rights of way shall be cleaned curb to curb on a weekly basis.
F. Construction ramps shall be constructed of material that will not erode or deteriorate under adverse conditions, and shall not be placed in a manner as to interfere with or block the passage of stormwater runoff.
G. No debris, dirt, aggregate or excavated materials, or construction supplies, shall be placed on the public right of way unless specifically permitted by the city in writing. In addition, public sidewalks shall not be removed, blocked, or otherwise rendered unusable by construction activity, equipment or materials, or portable toilets, unless a safe, usable alternate walkway, as approved by the city, is placed on the same side of the right of way by the contractor.
H. No owner or lessee of real property shall allow the property to be unoccupied, unused, vacant or undeveloped after the topsoil has been disturbed or the natural cover removed, unless control measures are undertaken to prevent mud, sand, dirt and gravel, or other material from migrating off site and entering the public right of way or a stormwater system.
I. All temporary erosion/sediment and construction waste control measures shall be removed after final site stabilization. Trapped sediment and other disturbed soil areas resulting from the removal of temporary measures shall be permanently stabilized within twenty one (21) days from removal of the temporary measures.
J. Channels which collect or concentrate stormwater shall be protected against erosion and contain energy dissipation measures to prevent erosion on adjoining lands. Existing unprotected channels shall be protected against further erosion in the course of site development. Any site development or construction shall preserve the existing stormwater management improvements.
K. Sediment resulting from erosion of disturbed soils shall be detained on site. Sediment shall either be stabilized on site or removed in an approved manner.
L. Any and all collected stormwater runoff shall be directed to infiltration basins or to an approved BMP. Permanent treatment of stormwater runoff shall be accomplished by directing all runoff to an infiltration basin or to an approved BMP.
1. Exceptions: Runoff may be discharged directly into dry wells or other overflow structures under the following circumstances:
a. When the increase in impervious surface, resulting from new construction or addition to existing structures, is less than three thousand (3,000) square feet.
b. Runoff from roofs.
M. When existing streets are widened or otherwise improved, runoff from the new impervious surface may be directed into existing storm drain facilities if the existing storm drain facility has sufficient capacity to accommodate the increased runoff. (Ord. 3455, 2012)