Chapter 13.14
STORMWATER DRAINAGE SYSTEM DEVELOPMENT CHARGES IN CERTAIN DESIGNATED DRAINAGE BASINS
Sections:
13.14.030 Drainage basins defined.
13.14.040 Stormwater drainage master plan.
13.14.050 System development charges – Basis.
13.14.060 Rate adjustment factor.
13.14.070 Construction of regional drainage facilities.
13.14.080 Reimbursement rights.
13.14.090 Payment of system development charges.
13.14.200 North and South Tumwater Hill drainage basins.
13.14.010 Definitions.
For the purposes of this chapter, the following definitions shall apply:
A. “City” means the city of Tumwater, Washington, or the area within the territorial limits of the city of Tumwater, Washington, and such territory outside of the city over which the city has jurisdiction or control by virtue of any constitutional or statutory provision.
B. “Dedication of land” means setting aside a portion of property for a specific use or function.
C. “Detention” means the process of collecting and holding back stormwater for later release to receiving waters.
D. “Drainage equivalent unit (DEU)” means the acreage of the property in question times a stormwater runoff factor (CN). CN is the Soils Conservation Service (SCS) runoff curve number which combines land use and soil type into a single number to be used to calculate stormwater runoff. DEU = (Area) x (CN).
E. “Easement” means the legal right to use a parcel of land for a particular purpose.
F. “Regional stormwater drainage facilities” means any natural stream/creek/channel or person-made component of the city’s storm drainage system as outlined in each stormwater drainage master plan.
G. “Retention” means the process of collection and holding stormwater with no surface outflow.
H. “Stormwater conveyance system” means a mechanism for transporting water from one point to another including pipes, ditches and channels.
I. “Stormwater drainage facilities” or “drainage facilities” means any natural stream/creek/channel or person-made component of the city’s storm drainage system.
J. “Stormwater drainage master plan” means that document consisting of the size and location of regional stormwater drainage facilities and other considerations and requirements established for certain stormwater drainage facilities and other considerations and requirements established for certain stormwater drainage basins or subbasins as outlined in this chapter.
K. “Subbasin” means the area which drains to a specified point within a drainage basin. Basin may be used as subbasin in this chapter.
L. “System development charge” means that assessment charged against a property benefiting from regional drainage facilities constructed or that will be constructed according to an adopted stormwater drainage master plan that serves said property based on land use factors described in TMC 13.14.050.
M. “Zoning” means to designate, by ordinances, areas of land reserved and regulated for different land uses.
(Ord. 1215, Added, 02/06/1990)
13.14.020 Purpose.
As a general policy, and as a condition of development approval, all developments in the city must allow for on-site detention/retention and treatment of stormwater runoff. The granting of easements, dedication of land, sizing of stormwater conveyance systems and water quality facilities has been the responsibility of the developer and their professional engineer. It is up to the city’s discretion whether to accept the ownership, operation and maintenance of said facilities. In areas of the city which are largely undeveloped, but where future growth is anticipated, it is possible to do advanced planning for regional stormwater drainage quality facilities on a basin-wide basis. In such cases, the preferred location of such regional facilities may be predetermined, and the cost of constructing the same may be assessed against benefited properties within the affected drainage basin at the time new development projects are proposed. In such cases, the city will accept the ownership, operation and maintenance of said facilities.
(Ord. 1215, Added, 02/06/1990)
13.14.030 Drainage basins defined.
Drainage basins to which this chapter shall apply may be located in whole, or in part, within the city limits. They shall be identified and defined by the public works department and adopted, by reference, by resolution of the city council.
(Ord. O96-027, Amended, 10/15/1996; Ord. 1215, Added, 02/06/1990)
13.14.040 Stormwater drainage master plan.
The public works department, and at times in conjunction with the proper officials of adjoining jurisdictions which may share drainage basins with the city, may develop stormwater drainage master plans for identified drainage basins and any subbasins located therein. Said plans shall predetermine the location and size of any proposed water quality facilities of regional significance, and the location and size of all drainage facilities downstream from the regional facilities or that link regional facilities. Conveyance to the facilities shall be the responsibility of new development. The stormwater drainage master plan for each basin shall be adopted, by reference, by resolution of the city council.
(Ord. O96-027, Amended, 10/15/1996; Ord. 1215, Added, 02/06/1990)
13.14.050 System development charges – Basis.
The acquisition and construction cost of such facilities, if not known, shall be estimated and shall be apportioned by a system development charge against all property in the drainage basin which may be expected to contribute stormwater runoff to the regional system at the time such property is developed. Other costs that may also be apportioned include easement acquisitions, permitting costs, master planning costs, engineering and inspection costs, surveying costs and appropriate contingency costs. If unknown, these costs may be estimated. The system development charge shall be based on the acreage of the property in the drainage basin which may be expected to contribute stormwater runoff to the regional system at the time such property is developed, and a storm runoff factor that is based on land use factors such as topography, soil class, impervious surfaces and other appropriate factors and a basin drainage equivalent unit. The drainage equivalent unit (DEU) for each basin and subbasin shall be adopted by ordinance of the city council and incorporated into this chapter.
(Ord. 1215, Added, 02/06/1990)
13.14.060 Rate adjustment factor.
A. If certain drainage facilities are constructed by the city and connections to these facilities are not made by properties expected to contribute stormwater runoff at the time such property is developed, the drainage equivalent unit (DEU) shall be annually adjusted (escalated) in accordance with the city’s reinvestment rate from the date of construction of said facilities. A finance charge of one percent annually shall be added to the investment rate to handle expenses.
B. If certain drainage facilities are not constructed within a year after the plan for the same is adopted, cost estimates shall be adjusted annually using the ENR Seattle Cost Index, beginning at the date of said adoption.
(Ord. 1215, Added, 02/06/1990)
13.14.070 Construction of regional drainage facilities.
Construction of regional drainage facilities shall be scheduled by the city to meet the needs of the basin or subbasin in question. Construction of said facilities may occur under the following conditions: Construction may be performed by the developer of the property on which the facilities are to be located as a condition of a development project; the city may require developers of other properties within the basin or subbasin to construct the facilities as a condition of their projects; or the city may construct the necessary facilities as outlined in the appropriate master plan. It is up to the discretion of the city what will be required of each development. Any parties constructing such facilities shall be reimbursed for the costs thereof as provided in TMC 13.14.080.
(Ord. 1215, Added, 02/06/1990)
13.14.080 Reimbursement rights.
Stormwater drainage master plans shall contain a breakdown of estimated project costs associated with the implementation of the city regional facilities identified in such plans. Costs that are known will be made part of the project cost. Unknown costs will be estimated and made part of the project cost. A summary of these project costs will be shown in each master plan. The total project cost will be assessed against properties expected to use regional drainage facilities outlined in the appropriate stormwater master plan. The city’s utility will also pay its share towards these regional facilities. A party who constructs a portion of the regional drainage facilities required by an adopted stormwater drainage master plan shall be entitled to reimbursement of the costs according to the estimate provided in the summary of project costs as outlined in the appropriate master plan and according to the following terms and conditions:
A. The facilities must have been installed and completed in compliance with the appropriate stormwater drainage master plan and/or as specified by the city and according to city standards. Said facilities shall be conveyed to the city.
B. Developers may, at the discretion of the city, construct a portion of the regional facility in lieu of paying their system development charge assessment if the estimated cost of that portion to be constructed is shown (in the stormwater drainage master plan, summary of project cost) to be of approximately the same value as the charge.
C. Any party may be required to construct said regional facilities or portions thereof as part of the conditions for development. In such case, the total reimbursement amount payable to any party shall be reduced by the system development charge for the property owned by said party in the subject basin/subbasin.
D. The final reimbursement amount, as determined by the city, will be paid by the city to the party constructing the drainage facilities, or their assigns. Funds used for such payments shall be derived from system development charges collected by the city from developments within the subject basin/subbasin during the period of fifteen years. Under no circumstances shall the city be liable for reimbursements in amounts greater than the total system development charges which it has collected from the subject basin/subbasin.
E. If the city has acquired land and/or constructed drainage facilities at its own cost, it shall be entitled to reimbursement from the system development charges collected from the subject basin/subbasin.
F. In the event that more than one party has constructed regional drainage facilities in a single basin/subbasin, and each of said parties has been approved by the city council as being entitled to reimbursement from system development charges collected by the city from property owners within that basin/subbasin, reimbursement shall be paid on the basis of chronological priority. The first drainage facilities which were accepted as completed by the city shall be reimbursed in full before any payments are made for subsequent facilities constructed in the same basin/subbasin.
(Ord. O96-027, Amended, 10/15/1996; Ord. 1215, Added, 02/06/1990)
13.14.090 Payment of system development charges.
System development charges in the amount specified in this chapter shall be paid by a property owner upon the first of the following events to occur:
A. As a condition of final approval of a subdivision;
B. As a condition of final approval of a short subdivision;
C. As a condition of final approval of a binding site plan for any mobile home park, condominium, planned unit developments, industrial park or shopping center;
D. As a condition of any building, grading, paving or other development approval which impacts drainage runoff.
(Ord. 1215, Added, 02/06/1990)
13.14.200 North and South Tumwater Hill drainage basins.
By Resolution No. 393 adopted by the city council on February 6, 1990, a stormwater drainage master plan for the North and South Tumwater Hill area was approved. The following system development charges are hereby adopted for all properties within these drainage basins that use or will use the regional drainage facilities for said basins.
DEU = Acreage x CN (Runoff Factor)
Cost per DEU = Total Project Costs/Sum of DEUs
(North Tumwater Hill = $32.08/DEU)
(South Tumwater Hill = $36.47/DEU)
System Development Charge = Project DEUs x Cost per DEU
The following are adopted CN (runoff factor) values for the North and South Tumwater Hill Drainage Basins:
Actual Land Use CN
Existing Forested Land 77
Green Belt 80
Residential Low 90
Residential Medium 93
Residential High 95
Residential Suburban 84
Commercial Low 95
Commercial Medium 96
Commercial High 98
(Ord. 1250, Amended, 08/21/1990; Ord. 1215, Added, 02/06/1990)