CHAPTER 12.14
DRAINAGE FACILITY IMPROVEMENTS AND DRAINAGE FEES
Section
12.14.020 Minimum requirements
12.14.010 DEFINITIONS.
For the purpose of this chapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
CHANNEL. An elongated open depression in the contour of land in which storm water may or does flow.
CONDUIT. A general term for any artificial or natural channel intended for the conveyance of storm water, whether open or closed, or any structure through which water flows.
CULVERT. A closed conduit for the free passage of surface drainage water under a highway, railroad, canal or other embankment.
DITCH. A trench for drainage or irrigation artificially made by digging.
DRAINAGE.
1. The process of removing surplus ground or surface water by artificial means;
2. The manner in which the waters of an area are removed;
3. The area from which waters are drained; a drainage basin.
DWELLING UNIT. A building or portion thereof designed exclusively for residential occupancy by one family for living purposes and having only one kitchen.
MAJOR DRAINAGE CHANNELS. The main stream tributaries that are the final discharge points for individual drainage areas.
MINOR DRAINAGE CHANNELS. A channel or conduit that ties to the secondary drainage channels.
PONDING AREA. A pond used for storage of storm water. It shall always contain some water and will have storage capacity in addition to its normal low flow level.
SECONDARY DRAINAGE CHANNEL. A channel or conduit tying directly to the major channels.
STREAM. Any course of running water flowing on the earth.
STORAGE BASIN. A holding basin for storage of storm water. Under normal circumstances it is dry but has storage capacity when flows exceed the capacity of the storm water drainage system.
SUBDIVIDER. A person, firm, corporation, partnership or association who proposes to divide, divides or causes to be divided real property into a subdivision for himself or for others except that employees and consultants of such persons or entities, acting in such capacity, are not “subdividers.”
SUBDIVISION. The division by any subdivider, of any unit or units of improved or unimproved land, or any portion thereof, shown on the latest equalized county assessment roll as a unit or as contiguous units, for the purpose of sale, lease or financing, whether immediate or future except for leases of agricultural land for agricultural purposes. Property shall be considered as contiguous units, even if it is separated by roads, streets, utility easement or railroad rights-of-way. Any conveyance of land to a governmental agency, public entity or public utility shall not be considered a division of land for purposes of computing the number of parcels. As used in this paragraph, “agricultural purposes” means the cultivation of food or fiber or the grazing or pasturing of livestock.
SUBDIVISION MAP ACT. Title 7, Division 2 of the Government Code of the State of California, as amended.
(Ord. 713, § 1, passed -- 1990; Am. Ord. 870, § 21, passed 8-25-2008)
12.14.020 MINIMUM REQUIREMENTS.
A. Runoff design. Storm water runoff from a subdivision shall be minimized by incorporation of Low Impact Development (LID) strategies that minimize impermeable areas, maximize permeable areas, and that slow, spread, and sink runoff so as to recharge groundwater and minimize runoff. Runoff that is expected shall be collected at vegetative swales or bioretention facilities and overflow finally conveyed by a storm drain system approved by the City Engineer. Maximum runoff shall be computed using the Rational Method. The Rainfall Intensity Duration Curve, for Fort Bragg, and “C” values derived from the General Plan Land Use Map, and are approved by the City Engineer shall be used in the computation. Runoff design shall accommodate the full and anticipated future development within the drainage area. In cases where the drainage areas are undeveloped, fully improved conditions shall be determined by the designation of the area on the General Plan or the zoning classification of the area. The storm drain system shall provide for the protection of the abutting properties that would be adversely affected by any increase in runoff attributed to the development, for which off-site storm drain improvements may be required.
B. Protection from surface waters. All portions of a subdivision shall be protected from flood hazard, inundation, sheet overflow, and ponding of storm waters springs and all other surface waters. All finished floors shall be a minimum of one (1) foot above the water surface of a 100-year frequency storm runoff.
C. Adequate storm drainage facilities.
1. The design of all improvements within a subdivision shall be such that all surface waters occurring within the subdivision, as well as all surface waters flowing onto and/or through the subdivision, shall be conveyed through the subdivision without damage to any improvement, building site, or dwelling which may be constructed within the subdivision. Storm drainage facilities within a subdivision shall be designed to adequately convey the storm water runoff from the ultimate development of the drainage basin or watershed.
2. Site development is to be accomplished wherever possible in a manner that will maximize percolation and infiltration of precipitation into the ground and will minimize direct surface runoff into adjoining streets, water courses, or properties.
3. Site development is to be accomplished wherever possible in a manner to maximize use of natural drainage features.
D. Surface water flowing from a subdivision. Surface water flowing from a subdivision in any form or manner shall be conveyed without damage to any improvement, building, or dwelling both within and downstream of the subdivision to a natural watercourse having a definable bed and banks, or to an existing adequate storm drainage facility. Storm drainage facilities to be constructed outside of the subdivision shall be designed to adequately convey the storm water runoff from the ultimate development of the drainage basin or watershed lying within and above the subdivision. Any surface waters detained or ponded on adjacent property(s) as the result of improvements constructed by the subdivider, shall not cause any damage to the property.
E. Storm water disposal restriction. Storm water flowing from a subdivision in any form or manner shall not be permitted to flow into any sanitary sewer or any other facility not specifically intended for storm water runoff.
F. Illicit Discharges. Illicit discharges to a stream or storm water conveyance are prohibited. Pollution of any storm drain inlet by anything other than rainfall and water is considered an illicit discharge and is not permitted.
G. Capacity of channels and conduits. All drainage channels, conduits, culverts, and appurtenant facilities shall have sufficient capacity to convey a 100-year flood frequency of occurrence runoff using a 12" culvert diameter as a minimum diameter.
H. Facilities design criteria. The ten-year frequency storm water shall be placed in conduits when the gutter flow comes within an inch of the top of the curb or when the flow encroaches on the traveled portion of a street. Open flow shall not be allowed across a street. Storm water shall be placed in closed conduits or lined channels, except that the City Engineer may recommend that an existing natural or unlined artificial water course, endowed with significant natural beauty or other scenic attractions, or a natural or unlined artificial water course that does not pose a safety hazard, be utilized for drainage with the improvements as may be designated. Drainage facilities shall meet the following minimum design requirements.
1. Closed conduit. The minimum conduit size shall be 12 inches under driveway crossings and 18 inches across streets. In general, all storm drain conduit shall be standard strength reinforced concrete pipe. All storm sewers shall have a minimum invert grade not less than that which will provide a minimum velocity of 2-1/2 feet per second for the design flow. Radii of curves in conduit must be approved by the City Engineer and shall not be less than those recommended by the pipe manufacturer.
2. Inlet structures. Standard inlet structures shall be constructed at each pickup point in the system. Inlets shall be of a design approved by the City Engineer and shall not be flooded with a ten-year frequency of occurrence runoff.
3. Closed conduits; minimum flow line. Minimum flow line gradients for closed conduits shall be not less than three (3) one-thousandth foot per foot.
4. Closed conduits or lined channels; outlet velocity. When the outlet velocity from a closed conduit or lined channel exceeds the maximum allowable velocity for the earth channels receiving the flow, suitable protective works such as riprap or a stilling basin shall be provided.
5. Earth channels; maximum design velocities. Maximum design velocities for natural or artificial earth channels shall be those specified by a registered civil engineer and approved by the City Engineer.
6. Earth channels; minimum velocities. Minimum velocities at design capacity for earth channels shall be three (3) feet per second.
7. Earth channels; side slopes. Side slopes for improved earth channels shall be those specified by a registered civil engineer and approved by the City Engineer, but in no instance shall side slopes be steeper than one horizontal to one vertical.
8. Lined channels; side slopes. Side slopes for lined channels shall be those specified by a registered civil engineer.
9. Ponding areas and storage basins when permitted. Storage of storm water drainage by means of ponding areas or storage basins may be permitted only with the approval of the City Engineer, after study of the proposed disposal basin topography and soil characteristics.
10. Subdrainage; where required. Subdrain facilities shall be provided where specified by the soil engineer controlling the work and other areas where deemed necessary by the City to prevent sliding or settlement of the earth surface. Facilities will be required to convey the subdrainage to an approved point of discharge.
11. Hydromodification to be avoided. Hydromodification is a term depicting deleterious adjustments to a native stream channel or waters of the state that increases that channel in width or depth in response to elevated storm water discharges which result themselves from a lack of permeable space where rainfall may infiltrate soils. Hydro-modification is to be avoided by including Low Impact Development design concepts in all developments. Infiltration of rainfall into permeable areas and conveying runoff to vegetative swales or bioretention areas are preferred methods in designing for storm water conveyance that maximizes receiving water quality.
I. Easements. Drainage easements and access easements shall be required. Easements shall generally be for the purpose of maintenance only, except that multiple use easements for public access may be required to be consistent with the Conservation and Open Space element of the Fort Bragg General Plan.
(Ord. 713, § 2, passed -- 1990; Am. Ord. 716, § 1, passed -- 1990; Am. Ord. 895, §§ 4-7, passed 07-11-2011)
12.14.030 DRAINAGE FEES.
A. The drainage plan and map entitled “2004 Storm Drainage Master Plan,” dated October 2004, on file with the City Clerk, is hereby adopted pursuant to §§ 66483 and 66487 of the State of California Government Code.
B. The City official having jurisdiction shall not issue a building permit for construction resulting in a 120-square-foot or more increase in ground coverage within the Fort Bragg Drainage Area until the fees as set forth in this section have been paid. The official having jurisdiction may accept cash, or other consideration (in the form of actual construction of a part of drainage facilities by the applicant or his or her principal) in lieu of the fee when authorized to do so by the City Engineer. This fee shall not be required if the requested permit is to perform one (1) of the following.
1. To replace a structure destroyed or damaged by fire, flood, wind, or acts of God. This exception is only to the extent that the resultant structure has the same or less ground floor square footage as the original structure; if the ground floor square footage is increased, the square footage of the additional ground floor area shall be used to determine if the fee is due.
2. To construct a swimming pool, patio, or driveway.
3. To construct facilities (including dwellings) on lots greater than twenty (20) acres in area, provided less than 10% of the lot area is covered by impervious surfaces.
4. If the subdivision is for the conveyance of land to a government agency, public entity, public utility, or abutting property owner where a new building lot or site is not created as a result of the conveyance.
C. In the case of a new subdivision, the subdivider shall pay 100% of the drainage fees at time of issuance of the building permit.
D. Storm drainage fees shall be established, from time to time, by City Council resolution. The fees will be adjusted annually, for implementation January 1st of each year, based on the change in the Engineering News-Record 20-City Construction Cost Index over the prior year.
1. Agricultural land (twenty (20) acre minimum) shall not be assessed an acreage fee.
2. Any development increasing the impervious area on a parcel by one hundred twenty (120) square feet or more shall pay a storm drainage fee at the rate established in the City’s Fee Schedule. Said fee shall be calculated by multiplying the area, in square feet, of the additional impervious area by the rate in the Fee Schedule.
3. For subdivisions, the drainage fee shall be determined by multiplying the storm drain fee by the net area of the subdivision excluding the area falling within the public street right-of-way.
4. Runoff coefficients used to calculate storm drainage fees shall be determined from the Land Use Designation Map of the Fort Bragg General Plan or as actually zoned. The runoff coefficients (C values) for each of the various land use designations shall be as follows:
|
|
Land Use Zoning |
Runoff Coefficient “C” |
|---|---|---|
|
Residential: |
||
|
RVH |
Very High Density Residential |
0.75 |
|
RM |
Medium Density Residential |
0.70 |
|
RH |
High Density Residential |
0.65 |
|
RL |
Low Density Residential |
0.55 |
|
RS |
Suburban Residential |
0.40 |
|
RR |
Rural Residential |
0.35 |
|
Commercial: |
||
|
CN |
Neighborhood Commercial |
0.85 |
|
CO |
Office Commercial |
0.85 |
|
CBD |
Central Business District |
0.85 |
|
CG |
General Commercial |
0.85 |
|
CH |
Highway Visitor Commercial |
0.85 |
|
Industrial: |
||
|
IH |
Heavy Industrial |
0.90 |
|
HD |
Harbor District |
0.85 |
|
IL |
Light Industrial |
0.85 |
|
Special Purpose Districts: |
||
|
PR |
Neighborhood Park |
0.30 |
|
A |
Agricultural |
0.30 |
|
FP |
Floodplain |
0.25 |
|
OS |
Regional Park and Agricultural Open Space |
0.20 |
5. Fee amounts are applicable to the proposed use. For example, a commercial use occurring in a residential zone shall pay a fee according to the commercial land use schedule.
E. With the filing of the improvement plans for the first unit of any subdivision, the subdivider or developer shall submit a master storm drainage plan for the entire area covered by the tentative map. In so doing, the subdivider or developer shall design the system to essentially conform to the Fort Bragg Drainage Study plan. The subdivider shall construct and dedicate to the City the necessary storm water drainage improvements.
F. Whenever permanent off-site storm drainage facilities are required by the City to be constructed and installed as a part of the subdivision, in connection with the development of the subdivision, the cost of construction of the storm drainage facilities shall be credited against storm drainage fees chargeable to the owners as defined in this section, provided the facilities are owned by the City at the time the owner pays the fees, or will be owned by the City upon the acceptance thereof by the City, until the amount of the credit is exhausted. In the event that the amount so credited under this section exceeds the storm drainage fees which are chargeable to the owner, the amount of the excess shall be reimbursed as determined by the City Engineer, based on the estimated cost of facilities at the time of original construction. The reimbursement will be based on the percentage of the area that other benefited lands are in relation to the City benefit area. The subdivider will be reimbursed by the City from moneys received from the benefiting lands pursuant to this section. Reimbursements under this subsection shall terminate ten (10) years after acceptance by the City of the construction and installation of the facilities on which the reimbursements are based.
G. The fee collected in connection with nonresidential projects where the increase in impervious area is larger than ten thousand (10,000) square feet shall not exceed 10% of the total project cost. When a partial fee is collected under this provision, the remaining portion shall be collected on the same basis at time of future construction activity. The fee collected in connection with construction projects on industrially zoned parcels larger than ten (10) acres shall be determined on a case-by-case basis following an evaluation of the need for new or upgraded facilities to accommodate the increased storm water discharge and the construction of storm water facilities by the applicant as a part of the project.
(Ord. 931, § 2, passed 07-24-2017)