Chapter 12.28


12.28.010    Definitions.

12.28.020    Purpose.

12.28.030    Applicability and general design considerations.

12.28.040    Materials.

12.28.050    Cost and expenses.

12.28.010 Definitions.

As used in this section, the following words shall have the following meanings:

(1) “Catch basin” means a structure that captures surface runoff and discharges it into an underground storm drain pipe system.

(2) “Cleanout” means a structure to allow access to a storm drain for cleaning.

(3) “Culvert” means a sewer or drain crossing under a road or embankment.

(A) The part of a road or embankment that passes over such a sewer or drain.

(B) The channel or conduit for such a sewer or drain.

(4) “Invert” means the bottom or flow line of a channel, pipe, or manhole.

(5) “Minor development” means any development that does not require site plan review, long plat review, or planned development review. (Ord. 1354, 2005)

12.28.020 Purpose.

(1) The purpose of these stormwater drainage development standards is to provide a consistent policy direction for physical improvements necessary for stormwater management.

(2) These standards apply to both minor development and minor repairs or upgrades that create or modify stormwater discharge. (Ord. 1354, 2005)

12.28.030 Applicability and general design considerations.

(1) When site conditions allow, stormwater shall be handled on-site through the use of dry wells or other on-site retention methods.

(2) Open ditches are highly recommended for better infiltration and maintenance purposes. However, the Westport street superintendent reserves the authority to decide if an open-end ditch or a culvert is applicable or required.

(3) The city of Westport may, at its discretion, require a soils analysis to be conducted prior to the approval of any proposed drainage.

(4) Engineered plans shall be submitted to the city along with an application to perform work on city road right-of-way.

(5) All new drainage culverts must be a minimum of 12 inches unless adjacent culverts upstream and downstream are a greater size, in which case the minimum requirement will be the dimensions of the surrounding culverts.

(6) Drainage culverts exceeding 12 inches require an inverted brush rack to be installed for maintenance and child safety purposes.

(7) Any new drainage installed to subsections (12) and (13) of this section in Westport relating to Winter Creek must be at least 60 inches in diameter and may not span more than 40 feet without a cleanout.

(8) Any construction project that would change a point of discharge of surface water, or the quantity of discharge, or that would discharge surface water at a higher velocity than the rate of discharge before construction, or that would add to pollution of surface waters, requires culvert installation unless the Westport street superintendent deems otherwise.

(9) All drainage culverts installed may not span more than 50 feet without a catch basin as a cleanout.

(10) Cleanouts are required for culverts with a length of 50 feet or greater unless open-ended.

(11) Any new construction that proposes to discharge to a wetland requires separate review for compliance with applicable stormwater and water quality standards.

(12) Any new drainage development that is to connect with existing drainage must have an engineered plan submitted before development occurs. The city street superintendent may waive the requirement for minor upgrades and noncommercial developments.

(13) Angles with a change in degree of 45 or more require a catch basin within the angle.

(14) It is the owner’s responsibility to obtain and cause to be recorded any necessary easements across private properties that are needed to connect a development site with an approved point of discharge. Dimensions and other characteristics of the easement area shall be approved by the public works department. Closed conduit systems are required when a drainage system must cross an intervening property.

(15) The city street superintendent retains the right to allow or prohibit tightlining stormwater runoff to city drainage facilities.

(16) Nothing in this code shall authorize stormwater discharges that direct stormwater toward adjacent lots. (Ord. 1354, 2005)

12.28.040 Materials.

(1) Pipe materials in public storm drains shall be double-walled corrugated plastic ABS. The street superintendent may authorize the installation of pipe materials from the following list where appropriate.

(2) Material abbreviations:

(A) ABS – Acrylonitrile butadiene styrene.

(B) AC – Asbestos cement.

(C) CI – Cast iron.

(D) DI – Ductile iron.

(E) PVC – Poly-vinyl chloride.

(F) CP – Concrete pipe.

(G) CMP – Corrugated metal pipe.

(H) CHDPE – Corrugated high density polyethylene. (Ord. 1354, 2005)

12.28.050 Cost and expenses.

(1) All costs and construction expenses relating to stormwater development shall be the owner’s responsibility.

(2) Cost of construction and installation may alternatively be paid by the city of Westport if a financial reimbursement agreement has been established between the city of Westport and owner or owner’s designee prior to development, stating that all expenses shall be reimbursed to the city of Westport at a later time. (Ord. 1354, 2005)