STORMWATER MANAGEMENT

Sections:
14.15.010 Title.
14.15.020 Purpose.
14.15.030 Definitions.
14.15.040 Applicability.
14.15.050 Design criteria and performance standards.
14.15.060 Easements.
14.15.070 Statement on building permit, final plat and/or site plan.
14.15.080 Disclaimer of liability.
14.15.090 Public and private responsibilities for maintenance of system.
14.15.100 Administration.
14.15.110 Administrative appeals.

14.15.010 Title.
The ordinance codified in this chapter shall be known as the "stormwater management ordinance of the city." (Ord. O-81-165 § 1, 1981).

14.15.020 Purpose.
In order to promote the public health, safety, and general welfare of the citizens of Lakewood, Colorado, these stormwater management regulations are enacted for the general purpose of assuring the proper balance between use of land and the preservation of a safe and beneficial environment. More specifically, the provisions of these regulations are intended to reduce property damage and human suffering and minimize the hazards of personal injury and loss of life due to flooding. This is to be accomplished by establishing runoff control, establishing responsibilities for maintenance and operation, and establishing technical standards and criteria for implementation of stormwater management. (Ord. O-81-165 § 2, 1981).

14.15.030 Definitions.
For purposes of this chapter, the words and terms used, defined, interpreted, or further described herein shall be construed as follows:
"City" means the City of Lakewood, Colorado.
"Control structure" means a facility constructed to regulate the rate of discharge of stormwater.
"Development" means any manmade change to real estate or property, including buildings or other structures, streets, parking lots, mining, dredging, filling, grading, paving, or excavating.
"Director" means the City Manager or his/her designee.
"Easement" means authorization by a property owner for use by another party or parties of all or any portion of his/her land for a specified purpose.
"Emergency excess stormwater passage" means a channel or swale formed in the ground surface to carry stormwater runoff through a specific area.
"Excess stormwater" means that portion of stormwater runoff which exceeds the transportation capacity of storm sewers or natural drainage channels serving a specific watershed.
"Five-year storm" means rainstorms of a specific duration having a twenty percent chance of occurrence in any given year.
"Infill development" means the development of land which:
1. Has previously been subdivided; or
2. Is described by a metes and bounds description and which can legally be developed without subdivision.
"Natural drainage" means water which flows by gravity in channels formed by the surface topography of the earth prior to changes made by the efforts of man.
"Natural state" means land with soil and vegetation conditions that existed prior to any manmade activity on the land.
"New development" means the development of land which has not been previously legally subdivided.
"One-hundred year storm" means rainstorms of a specific duration having a one percent chance of occurrence in any given year.
"Safe stormwater drainage capacity" means the quantity of stormwater runoff that can be transported within a channel, passage, conduit, tube, duct, or combination thereof, in such a manner that the elevation of the water does not rise above the level of the adjacent ground surface so as to cause any damage to structures or facilities located thereon.
"Stormwater detention area" means an area designated to temporarily accumulate excess stormwater.
"Stormwater management system" means all facilities used to control stormwater, including stormwater pipes, stormwater detention areas, berms, channels, swales, control structures, easements, emergency excess stormwater passages, irrigation systems, improved watercourses, and any other facility or appurtenances used in the management of stormwater.
"Stormwater runoff" means water that results from precipitation which is not absorbed by the soil, evaporated into the atmosphere, or entrapped by ground surface depressions and vegetation, and which flows over the ground surface.
"Stormwater runoff release rate" means the rate (quantity per unit of time) at which stormwater runoff is released from upstream to downstream land.
"Tributary watershed" means the entire catchment area that contributes stormwater runoff to a given point. (Ord. O-81-165 § 3, 1981).

14.15.040 Applicability.
Any person, firm, corporation or business proposing to construct buildings or develop or redevelop land within the city shall be required to provide stormwater runoff control meeting the requirements of this chapter whenever the total area of land under identical ownership, including the land to be developed or upon which buildings are to be constructed, equals or exceeds those shown in the following chart. This chart applies to both building permits and subdivision of land.

Type of Development Zoning Classification Area

New and infill CN Exempt
New and infill 1R, 2R, 3R and single-family 2 acres
and duplex portions of PD

Type of Development Zoning Classification Area

New and infill 4R, 5R, 6R, OF, 1-C, 2-C, 3-C, 1 acre
4-C, IN, and multifamily through
industrial portions of PD

(Ord. O-94-40 § 6, 1994; Ord. O-81-165 § 4, 1981).

14.15.050 Design criteria and performance standards.
It shall be the duty of an applicant for a building permit or subdivision of land to provide a stormwater management system as provided in this section.
A. Design Criteria. Unless otherwise provided, the engineering regulations, construction specifications design standards, and amendments adopted by the City Council, shall govern the design of improvements with respect to managing stormwater runoff.
B. Stormwater Runoff Release Rate. Any person meeting the application provisions of this chapter as specified in Section 14.15.040 shall control the release rate of stormwater runoff so that runoff after development shall not exceed the runoff from the same parcel of land in its natural state for the five-year and one-hundred-year storm respectively.
C. Determination of Detention Volume. The volume of required water detention shall be calculated on the basis of runoff from the five-year and one-hundred-year return frequency storms. Such calculations should be made in accordance with a method of analysis in the Urban Storm Drainage Criteria Manual, published by the Denver Regional Council of Governments, unless specified otherwise by the Director.
D. Compensating Detention. In the event that orderly and reasonable development of an area requires that the detention of stormwater be located elsewhere, compensating detention (the detention of an equal volume of stormwater) may be provided at an alternative location if approved by the Director.
E. Partial and Full Exemption. When it can be demonstrated by the applicant to the Director that a higher stormwater release rate will not be contrary to the purpose and intent of this chapter and where such proposed release rate will not exceed the safe stormwater drainage capacity in the downstream portion of the watershed, the release rate may be increased or decreased as deemed appropriate by the Director. When determining the safe stormwater drainage capacity in the downstream portion of the watershed, it shall be assumed that all undeveloped land in the tributary watershed would be granted the same exemption as the applicant. If the safe stormwater drainage capacity is exceeded under these conditions, the applicant's release rate will be decreased so that the safe stormwater drainage capacity is not exceeded.
F. Emergency Excess Stormwater Passage. An excess stormwater passage shall be provided for all stormwater detention areas. Such passage shall have the capacity to convey through the proposed development the excess stormwater for the tributary watershed. The capacity of such stormwater passage shall be constructed in a manner to transport the peak rate of runoff from the one-hundred-year frequency storm assuming all storm sewers are inoperative, all upstream areas are fully developed, and that antecedent rainfall has saturated the tributary watershed.
No buildings or structures shall be constructed within the excess stormwater passage; however, streets, parking lots, playgrounds, park areas, pedestrian walkways, utility easements and other open space uses shall be considered compatible uses within the excess stormwater passage.
Where a proposed development contains an existing natural drainage channel, appropriate land planning shall be undertaken to preserve the natural drainage channel as part of the excess stormwater passage. (Ord. O-81-165 § 5, 1981).

14.15.060 Easements.
A. Easements which cover the outlet structure, low flow pipe, stormwater pipes, detention area berms, and other parts of the stormwater management system as the city deems desirable, shall be granted to the city. These easements are to be deeded for the purposes of operation, repair, alteration, and maintenance in areas composed of single-family detached dwellings and two-family dwellings or in other developments when the city has accepted maintenance and operation responsibilities.
B. All developments which have publicly owned easements shall provide covenants running with the land stating that no buildings, fills, excavations, structures, fences, or other alterations shall be constructed within a publicly owned easement without the express written consent of the city.
C. The enactment of the ordinance codified in this chapter is not intended to modify or alter any existing easement or rights-of-way for storm drainage purposes, but is intended to establish criteria for construction and maintenance and operation of new storm drainage facilities, both public and private. (Ord. O-81-165 § 7, 1981).

14.15.070 Statement on building permit, final plat and/or site plan.
When the city has determined that maintenance and operation of the stormwater management system is to be a private responsibility, the building permit, final plat and/or site plan of that development shall have language stating that the maintenance and operation of the stormwater management system will remain the responsibility of the property owner and his heirs, successors, and assigns. (Ord. O-81-165 § 8, 1981).

14.15.080 Disclaimer of liability.
The criteria set forth in this chapter establish minimum requirements which must be implemented with good engineering practice and workmanship. Use of the requirements in this chapter shall not constitute a representation, guarantee, or warranty of any kind by the city as to the adequacy or safety of any stormwater management system. Larger storms may occur or stormwater runoff heights may be increased by manmade or natural causes. These regulations shall not create liability on the part of the city with respect to any legislative or administrative decision made under this chapter. (Ord. O-81-164 § 9, 1981).

14.15.090 Public and private responsibilities for maintenance of system.
A. Public Responsibilities. In areas constructed exclusively as single-family detached dwellings or two-family detached dwellings, the city shall be responsible, after acceptance of the stormwater management system, for the maintenance and operation of any stormwater management system within a public easement. It is the intent of the city to provide for maintenance and operation of stormwater facilities in areas of single-family detached dwellings and two-family detached dwellings, provided there are public easements within which maintenance and operation can be done, and provided all design, construction, and maintenance criteria of the city are followed. Maintenance and operation of condominiums, multifamily, commercial, industrial and other uses shall be done by other persons as stated in subsection (B) of this section. In areas of mixed use such as multifamily housing and single-family detached dwellings, the Director will decide on a case-by-case basis whether maintenance and operation will be performed by the city.
B. Private Responsibilities. If the Director has determined that the city will not accept the responsibility for maintenance and operation of a stormwater management system, the owner of the land then has the responsibility for the maintenance and operation of the stormwater management system. Such responsibility shall be assumed by subsequent owners.
If the city has determined that the property owner has not properly maintained or operated the stormwater management system, the Director shall cause notice to be served upon the property owner. Such notice shall be in writing, signed by the Director, and shall be personally served upon the property owner. The notice shall specifically state why the stormwater management system has been determined to be improperly maintained or operated and the procedures which must be undertaken to correct the system's deficiencies.
Any person wishing to appeal the city's determination that the stormwater management system has not been properly maintained or operated shall file a written petition with the Director as described in Section 14.15.110. If the property owner does not appeal or correct the deficiencies within fourteen days of service of the notice, the city has the right to enter the property, maintain the stormwater management facilities, and require reimbursement for the costs that may be incurred by the city. (Ord. O-81-165 § 6(C), 1981).

14.15.100 Administration.
This chapter shall be administered by the Director. (Ord. O-81-165 § 6(A), 1981).

14.15.110 Administrative appeals.
A. Any person affected by any decision of the Director which has been given in connection with the application and enforcement of this chapter may appeal the decision to the Planning Commission. The appeal shall be filed within seven days of the decision of the Director.
B. Any person appealing the decision shall file a written petition with the Director and set forth a brief statement concerning the purpose of the hearing. Upon receipt of the petition, the Director shall set a time and place for such hearing and shall provide written notice to the petitioner. At such hearing, the petitioner shall be given the opportunity to be heard and show why any decision should be modified or withdrawn. The hearing shall be commenced not later than forty-five days after the date on which the petition was filed.
C. Any person aggrieved by the decision of the Planning Commission may seek relief in any court of competent jurisdiction as provided by the laws of Colorado. Any appeal pursuant to this section shall not stay the effect of the Director's order unless so ordered by the Planning Commission. (Ord. O-81-165 § 6(B), 1981).

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