San Anselmo Municipal Code Ch. 12 Watercourses

The free and unobstructed flow of water in the Town is essential to the proper drainage of the Town and to the protection of life and property therein. Any improperly designed improvement, earth, rocks, litter, household trash, rubbish, garbage, debris, weeds, brush, stumps, trees, or any other natural growth or any other material or matter, whether indigenous or nonindigenous which, at any time, interferes with or obstructs the free flow of water in a watercourse constitutes a threat to the public and therefor a public nuisance or code violation and is subject to citation, summary abatement and/or abatement in accordance with this Municipal Code, and/or any other provisions of the law.

(§ 1, Ord. 1059, eff. December 27, 2007)

For the purpose of this chapter the words set out in this section shall have the following meanings:

(a) "Channel" means an elongated open depression in which water may or does flow.

(b) "Conduit" means a general term for any artificial or natural channel intended for the conveyance of water whether open or closed.

(c) "Ditch" means an artificial channel created for the conveyance of water.

(d) "Drainage" means:

(1) The process of removing surplus ground or surface water by artificial or natural means; or

(2) The manner in which the waters of an area are removed; or

(3) The area or basin from which waters are drained.

(e) "Person" means any person, owner, tenant, occupant, firm, partnership or corporation.

(f) "Stream" means any course of running water flowing on the earth or in a channel.

(g) "Watercourse" is a general term for a bed in which water may or does flow. It includes: "channels," "conduits," "ditches," "stream" and similar conditions.

(§ 1, Ord. 1059, eff. December 27, 2007)

It is unlawful for any person to divert, obstruct, or alter in any way the courses or bed of any watercourse, drainage basin or channel within the Town, except in cases approved by the Department of Public Works and/or the Director of Public Works.

(§ 1, Ord. 1059, eff. December 27, 2007)

It is unlawful for any person to deposit, or cause to be deposited, or to permit to accumulate in any watercourse any litter, brush, stumps, earth, household trash, rubbish, or garbage or any other material or matter which can or may obstruct, divert or interfere with the natural flow of water, or to deposit, or cause to be deposited, or to permit to accumulate any of the aforementioned material in, or on, any bank adjacent to the watercourse.

(§ 1, Ord. 1059, eff. December 27, 2007)

(a) It shall be the responsibility of each owner, occupant or tenant of any real property within the Town not to cause or allow obstruction of any watercourse(s) or portion thereof which flows upon, under, over, or across the property and to maintain and to keep the watercourse(s) clear of all earth, rocks, litter, household trash, rubbish, garbage, or debris, or brush, stumps, trees or other natural growth, or any other material or matter, whether indigenous or nonindigenous which can or may obstruct, divert, or interfere with the flow of water in the watercourse(s).

(b) It shall be the further responsibility of each such owner, occupant and tenant to keep in good repair any pier, retaining wall, bulkhead, building bridge or other structure built over, in or adjacent to any watercourse on the property of such owner, occupant or tenant within the Town.

(c) The failure to comply with any of the provisions of this section shall constitute a public nuisance which may be abated in accordance with Chapter 2 Title 1 and the costs and attorneys fees incurred thereof assessed against the property. The Director of Public Works and the Director's authorized representatives may enter private property to abate the public nuisance.

(§ 1, Ord. 1059, eff. December 27, 2007)

It is unlawful for any person to construct or repair any pier, retaining wall, slope protection structure, dam, bulkhead, building, bridge or other structure in, over, or within fifteen (15') feet of the bank of any watercourse within the Town without rust obtaining a permit therefor from the Director of Public Works. Any and all such work done under such a permit shall be subject to inspection by the Public Works Department and/or the Building Department of the Town as the work progresses.

(§ 1, Ord. 1059, eff. December 27, 2007)

Any person wishing to construct or repair any of the structures mentioned in Section 7-12.06 shall submit to the Department of Public Works an application containing the following information:

(a) The name and address of the applicant;

(b) Location where such work is to be done;

(c) Description of the work to be done, together with the materials to be used, and if the Director of Public Works, or his representative, deems it necessary, plans and calculations prepared by a registered civil engineer all as described in this chapter;

(d) Total estimated cost of the proposed work;

(e) A statement that upon receipt of any permit or permits the applicant will commence work within fifteen (15) days or a time designated by the Department of Public Works, after the permit issuance date and will prosecute the work to completion with reasonable diligence;

(f) Such other information, including but not limited to special tests, as the Director of Public Works or the Director's representative deems necessary.

(§ 1, Ord. 1059, eff. December 27, 2007)

The applicants shall, at the time of filing their application, pay such fee as is set forth by resolution of the Town Council.

(§ 1, Ord. 1059, eff. December 27, 2007)

Hydrologic design shall be predicated upon ultimate development of the tributary watershed. Flood flows to be used for the design of waterways, channels, and closed conduits shall accommodate existing flow or have minimum average recurrence intervals as follows, whichever is greater:

(a) Major waterways have a drainage area of four (4) square miles or more and shall be designed for an average recurrence interval of 100 years.

(b) Secondary waterways have a drainage area of between forty (40) acres and four (4) square miles and shall be designed for an average recurrence interval of twenty-five (25) years.

(c) Minor waterways have a drainage area of forty (40) acres or less and shall be designed for an average recurrence interval of ten (10) years.

(§ 1, Ord. 1059, eff. December 27, 2007)

(a) General. For the solution of hydraulic design problems, the design engineer shall provide reference, model studies, reports, and prototype tests, as is necessary to confirm the hydraulic design.

The elevations of facilities adjacent to waterways shall be designed such that no more than nuisance damage to improvements or projected improvements, and no inundation of present or future buildings shall result from a 100 year design storm.

Design depth of flow in gutters shall not exceed five (5″) inches for the ten (10) year flow. Where the discharge exceeds gutter capacity, a closed conduit system shall be provided, otherwise roadside ditches may be allowed; provided, that no floodwater from a ten (10) year flow will be permitted to encroach into the traveled way.

(b) Open channel systems. Open channel systems shall designed to carry the quantity of flow determined as set forth in hydrologic design cross-section with adequate freeboard between design water surface and the top of bank.

Bridges, culverts, and utility crossings which span major and secondary open channel waterways shall have a minimum clearance from soffit to design water surface of two (2′) feet. The design depth in circular conduits shall not exceed eight-tenths ( 8/1 0) of the conduit for major and secondary waterways.

(c) Pressure flow system. Minor waterways placed in pressure flow systems may be designed for full conduit capacity; provided, that adequate provisions are made for losses such as friction, bends, transitions, debris, entrance conditions and exit conditions; and provided further, that adequate freeboard is provided at the entrance and at all inlets to the system.

(d) Alignment, slope protection and structural design. Structures shall be designed and constructed so that hydraulic conditions for both the upstream and downstream waterway will not be altered in a way which would cause degradation, erosion, increased water surface elevation or other undesirable effects.

In the case of slope protection, this requirement typically will necessitate the excavation of the creek bank to create a cavity to allow for the placement of slope protection material without reducing the cross sectional flow area of the drainage course.

(e) Constructed channels.

(1) Minimum radii. Minimum centerline radii for curves in constructed channels and waterways shall be three (3) times the top width of the channel.

(2) Side slopes. Grassed channels or loose rock riprapped channels shall have side slopes not steeper than two to one (2:1). Lined channels shall have side slopes not steeper than 1.5 to one (1) unless designed structurally to resist all lateral loads applied to bank lining. Channels shall have flatter side slopes if soil instability appears probable from field investigation. Design of slopes in unstable soils shall be predicated upon results of an investigation by a registered professional engineer qualified in soils engineering. Earth channels, in those areas not otherwise protected, shall be planted with an approved grass seed to establish a vegetative cover to the top of channel banks.

(3) Hydraulic jump. At drop structures or in other locations where a hydraulic jump may be formed, bank and channel invert protection shall be provided.

(f) Conduits.

(1) Minimum size. Minimum dimension of conduits shall be fifteen (15") inches except for subdrains and roof leaders.

(2) Entrances. Entrances structures shall be designed to allow passage of water with anticipated debris loading at entrance.

(3) Alignment. The alignment of closed conduits shall be as nearly straight as practicable. Manholes or some other acceptable means of access shall be provided at or near all junctions, at all bends which are sharper than those formed by standard single bevel concrete pipe, and at intervals not to exceed 400 feet along the conduit.

(4) Catchbasins. Catchbasins shall be located on the uphill side of curb returns whenever the gutter slope exceeds two (2%) percent or when the computed gutter flow reaches a depth of one and one-half (1½″) inches or more. Nongrated catchbasins shall be placed in all areas that may be used by bicycles. If the gutter slope exceeds three (3%) percent, a drainage gallery should be used to direct the flow into the catchbasin. Gallery length shall depend on the respective gutter slope. If practical, gutter flow should be intercepted uphill of crosswalks.

(5) Gradients. The gradient for earth ditches shall not exceed four (4%) percent nor be less than one (1%) percent. The gradient for lined or paved ditches and gutters shall be not less than 0.5 percent.

(6) Structural design. Closed conduits, including nonreinforced and cast-in-place concrete pipe, shall be structurally designed to withstand earth and surcharge loads normally anticipated to be imposed thereon. Clearance between top of pipe and ground shall be sufficient to preclude displacement of or damage to conduit by all loading and surface land uses.

(7) Conduit materials. Conduits shall be designed to have a minimum useful life of fifty (50) years. Normally, galvanized metal conduit will not be acceptable except for driveway crossings and outlets into open waterways. When galvanized metal conduit is allowed, extra protection shall be provided to prolong life. In the event of erosive conditions, extra wearing surface will also be required.

Closed conduits outletting into open channels or waterways shall be galvanized corrugated metal pipe with appropriate protective coating for approximately the last twenty (20′) feet immediately upstream of the outlet. Such pipes shall be connected to nonmetal conduit by means of a concrete collar reinforced with welded wire fabric.

(8) Outlets. Excessive outlet velocities should be limited and controlled, if necessary, with an energy-dissipator structure. Endwalls should be adequately designed to protect the embankment.

(g) Elevation datum. Wherever a minimum elevation is stated, it shall be based on the National Geodetic Vertical Datum (NGVD) of 1929 and shall refer to the elevation predicated after ultimate settlement has taken place.

(h) Erosion and sediment control. All graded surfaces, including cut-and-fill slopes, shall be adequately protected against erosion by the installation of erosion-resistant planting or other appropriate measures. Permanent vegetation and other measures for erosion and sedimentation control shall be completed as soon as possible: however, such installation(s) shall be completed no later than two (2) weeks prior to the onset of the rainy season except as provided in this section. The rainy season shall be considered as the period from October 15th to April 15th. Where cut slopes are not subject to erosion due to the erosion-resistant character of the materials. The Director of Public Works may waive the requirement to provide such protective devices.

Grading operations shall not be conducted during the rainy season except upon a clear demonstration, to the satisfaction of the Director of Public Works, that at no stage of the work will thereby create substantial increased risk of erosion, sliding or sediment discharge from the site. When grading operations are permitted during the rainy season, the smallest practicable area of erodible land shall be exposed at any one (1) time during grading operations and the time of exposure shall be minimized.

Runoff shall not be discharged from the site in quantities or at velocities substantially above those which occurred before grading except into approved drainage facilities.

The design and installation of erosion and sediment control facilities shall comply with the approved recommendations of the project designer involved in the preparation of the grading design. The specific erosion and sediment control measures to be utilized shall be in general accordance with the various measures described in the current "Manual of Standards for Erosion and Sediment Control Measures" published by the Association of Bay Area governments.

(i) Drainage and terracing. Unless otherwise indicated on the approved grading plan, drainage facilities and terracing shall conform to the following provisions: Terraces at least six (6') feet in width shall be established at not more than thirty-foot (30') intervals to control surface drainage and debris. Suitable access shall be provided to permit proper cleaning and maintenance of the terraces.

Swales or ditches on terraces shall have a minimum gradient of five (5%) percent and must be paved with reinforced concrete or an approved equal paving.

A single run of swale or ditch shall not collect runoff from a tributary area exceeding 13,500 square feet (projected) without discharging into a down drain.

Drainage collection systems shall discharge water in an area of undisturbed stable soil.

(j) Subsurface drainage. Cut and fill slopes shall be provided with subsurface drainage as necessary for stability.

(§ 1, Ord. 1059, eff. December 27, 2007)

If it is determined by the Director of Public Works, or the Director's representative, that special tests, such as, but not limited to, soil tests, compaction tests, or material tests, are necessary for a proper determination of whether to issue or deny the permit, the applicant shall furnish the Town with such tests or pay to the Town a sufficient amount of money to pay for the actual cost of such tests. If the applicant does not furnish the Town with such tests or pay the sum of money within ten (10) days or such longer period of time as the Director of Public Works designates, the application shall be denied.

(§ 1, Ord. 1059, eff. December 27, 2007)

Before issuing any building permit for the erection or construction of any pier, retaining wall, bulkhead, building, bridge or any other structure, the building inspector shall determine whether or not such pier, retaining wall, bulkhead, building, bridge or structure will interfere with the free flow of any watercourse. If in the opinion of the Building Inspector such a pier, retaining wall, bulkhead, building, bridge or other structure will interfere with the free flow of water in any season, the building permit shall not be issued until the applicant or owner of the premises involved has made ample provision for the free flow of water in the watercourse. The building permit may be issued only after provision for the flow of water has been installed or upon the posting of a bond to complete such work within such time and within such amount as the Building Inspector may require.

(§ 1, Ord. 1059, eff. December 27, 2007)

If the Director of Public Works, or the Director's representative, determines after review of the permit application that the work will not:

(a) Interfere with the flow of storm waters;

(b) Damage other property; and

(c) Complicate normal drainage maintenance; the Director of Public Works shall issue a permit to perform the proposed work in the manner specified in the application, or in such a manner as the Director of Public Works may determine is required to carry out the purposes of this chapter. The Director may impose such terms and conditions as the Director may deem necessary to insure the proper maintenance of the property for flood control and drainage purposes. The permittee will assume all responsibility for the consequences of any work done or use permitted under the permit. The issuance of a permit by the Director of Public Works shall not be construed as subjecting the Town to any liability whatsoever for work done or uses permitted under the permit, nor shall the issuance of a permit be construed as relieving the permittee or owner of the property from any such liability to the extent that it may exist.

(§ 1, Ord. 1059, eff. December 27, 2007)

Any permit required by this Chapter 12, Title 9 may be revoked by the Director of Public Works, or the Director's representative, if the Director determines the public interest and welfare require the revocation, or if there is a violation of this chapter or the terms and conditions of the permit.

(§ 1, Ord. 1059, eff. December 27, 2007)

In the event the permittee does not complete the work in accordance with the terms and conditions of the permit within fifteen (15) days or such longer period of time as the Director of Public Works designates, and if the removal or completion of such work is essential to the health, welfare and safety of the public, the Director of Public Works may cause the work to be removed or completed at the expense of the property owner or permittee. In the event the costs are not paid within thirty (30) days after notification, the costs shall become a special assent and lien against the real property involved; and the assessment may be collected at the same time and in the same manner as ordinary municipal taxes are collected, and shall be subject to the same penalties and the same procedure and sale in case of delinquency as provided for ordinary municipal taxes. All laws applicable to the levy, collection and enforcement of municipal taxes shall be applicable to such special assessment.

In the event any person shall divert, obstruct, or interfere with any watercourse, drainage course, channel, or stream in violation of the provisions of this chapter or allow any pier, retaining wall, bulkhead, building, or any other structure to become in such disrepair so as to cause any of the above conditions, the Director of Public Works may take any necessary action to correct the condition at the expense of the property owner, and such expenses shall become a special assessment and lien on the real property involved, and subject to collection in the same manner as ordinary municipal taxes are collected and shall be subject to the same penalties and the same procedure and sale, in case of delinquency as provided for ordinary municipal taxes.

In addition to the foregoing, the Town may use any other lawful means to collect the cost of any work performed by the Town or on its behalf pursuant to the provisions of this section.

(§ 1, Ord. 1059, eff. December 27, 2007)

Any person aggrieved by the action of any official of the Town in the denial, suspension or revocation of any permit required by this chapter, shall have the right of appeal to the Town Council by following the appeal procedure described in Chapter 1, Title 10 Planning and Zoning, of this Municipal Code.

(§ 1, Ord. 1059, eff. December 27, 2007)

Any person as herein defined who violates any provision or fails to comply with any requirements of this chapter is guilty of either a misdemeanor or an infraction or a public nuisance which may be abated, as described in this Code. Each such person is guilty of a separate offense for each and every day during any portion of which any violation of any provision of this chapter is committed, continued or permitted by such person and shall be punished accordingly.

(§ 1, Ord. 1059, eff. December 27, 2007)