Crescent City City Zoning Code
CHAPTER 17
84B CALIFORNIA COASTAL ZONE RESOURCE PROTECTION PROCEDURES WATER QUALITY
§ 17.84B.010 Purpose.
This chapter implements applicable provisions of the local coastal program for ensuring the protection of the quality of coastal waters by providing standards for the review, authorization, and conditioning of new development and land uses consistent with the requirements of the California Coastal Act.
(Ord. of 2-22-2011(1))
§ 17.84B.020 Applicability.
The provisions of this chapter apply to the review of coastal development permit applications for all development or uses proposed on sites that entails construction, grading, or other activities that involve ground disturbance, increases in impervious surface areas, or alterations in the direction, volume, or flow rate of surface or groundwater hydrology.
(Ord. of 2-22-2011(1))
§ 17.84B.030 Coastal development permit application contents.
In addition to the information required by Section 17.84.020 for coastal development permit applications, the applicant shall provide the following supplemental information:
A.
Construction pollution control plan. A construction-phase erosion, sedimentation, and polluted runoff control plan ("construction pollution control plan") shall specify interim best management practices (BMPs) that will be implemented to minimize erosion and sedimentation during construction, and prevent contamination of runoff by construction chemicals and materials, to the maximum extent practicable. The construction pollution control plan shall demonstrate that:
1.
During construction, development shall minimize site runoff and erosion through the use of temporary BMPs (including, but not limited to, soil stabilization measures), and shall eliminate the discharge of sediment and other stormwater pollution resulting from construction activities (e.g., chemicals, vehicle fluids, asphalt and cement compounds, and debris), to the extent feasible.
2.
Land disturbance activities during construction (e.g., clearing, grading, and cut-and-fill) shall be minimized, to the extent feasible, to avoid increased erosion and sedimentation. Soil compaction due to construction activities shall be minimized, to the extent feasible, to retain the natural stormwater infiltration capacity of the soil.
3.
Construction shall minimize the disturbance of natural vegetation (including significant trees, native vegetation, and root structures), which is important for preventing erosion and sedimentation.
4.
Development shall implement soil stabilization BMPs, including but not limited to re-vegetation, on graded or disturbed areas as soon as feasible.
5.
Grading operations shall not be conducted during the rainy season (from October 1 to April 15), except in response to emergencies, unless the County determines that soil conditions at the project site are suitable, the likelihood of significant precipitation is low during the period of extension, (not to exceed one week at a time), and adequate erosion and sedimentation control measures will be in place during all grading operations.
6.
The construction pollution control plan shall be submitted with the final construction drawings. The plan shall include, at a minimum, a narrative report describing all temporary polluted runoff, sedimentation, and erosion control measures to be implemented during construction, including:
a.
Controls to be implemented on the amount and timing of grading.
b.
BMPs to be implemented for staging, storage, and disposal of excavated materials.
c.
Design specifications for structural treatment control BMPs, such as sedimentation basins.
d.
Re-vegetation or landscaping plans for graded or disturbed areas.
e.
Other soil stabilization BMPs to be implemented.
f.
Methods to infiltrate or treat stormwater prior to conveyance off-site during construction.
g.
Methods to eliminate or reduce the discharge of other stormwater pollutants resulting from construction activities (including but not limited to paints, solvents, vehicle fluids, asphalt and cement compounds, and debris) into stormwater runoff.
h.
BMPs to be implemented for staging, storage, and disposal of construction chemicals and materials.
i.
Proposed methods for minimizing land disturbance activities, soil compaction, and disturbance of natural vegetation.
j.
A site plan showing the location of all temporary erosion control measures.
k.
A schedule for installation and removal of the temporary erosion control measures.
7.
A list of "good housekeeping" provisions including but not limited to inventory of products and chemicals used on site, plans for the cleanup of spill and leaks, and on site inspections by a qualified sediment and water quality control specialist.
B.
Post-Construction Stormwater Plan. A plan to control post-construction stormwater runoff flows, and maintain or improve water quality ("post-construction stormwater plan") shall specify site design, source control, and if necessary, treatment control BMPs that will be implemented to minimize stormwater pollution and minimize or eliminate increases in stormwater runoff volume and rate from the development after construction. Water quality treatment BMPs shall prioritize the integration of site design BMPs over source control BMPs over treatment control BMPs. The post-construction stormwater plan shall demonstrate that:
1.
Following construction, erosion on the site shall be controlled to avoid adverse impacts on adjacent properties and resources.
2.
Permanent erosion control measures shall be installed, as may be needed, depending upon the intensity of development proposed and the sensitivity of receiving waters.
3.
Runoff from the project shall not increase sedimentation in receiving waters.
4.
On-site filtering, grease, and/or sediment trapping systems shall be installed, as needed, to capture any pollutants contained in the runoff.
5.
Permanent runoff/drainage control improvements, such as subsurface drainage interception, energy dissipaters, recovery/reuse cisterns, detention/retention impoundments, etc. shall be installed, as needed, at the point of discharge.
6.
In the application and initial planning process, the applicant shall submit a preliminary postconstruction stormwater plan, and prior to issuance of a building permit the applicant shall submit a final post-construction stormwater plan for approval by the County. The plan shall include, at a minimum, the following components:
a.
Proposed site design and source control BMPs that will be implemented to minimize postconstruction polluted runoff.
b.
Proposed drainage improvements (including locations of infiltration basins, and diversions/ conveyances for upstream runoff).
c.
Measures to maximize on-site retention and infiltration (including directing rooftop runoff to permeable areas rather than to driveways).
d.
Measures to maximize, to the extent practicable, the percentage of permeable surfaces, and to limit the percentage of directly connected impervious areas, to increase infiltration of runoff.
e.
Methods to convey runoff from impervious surfaces into permeable areas of the property in a non-erosive manner.
f.
A site plan showing the location of all permanent erosion control measures.
g.
A schedule for installation and maintenance of the permanent erosion control measures.
h.
A schedule for installation and maintenance of the sediment and debris filtration, grease and/or sediment trap, etc., as warranted for the type of development and site.
i.
A site plan showing finished grades in one-foot contour intervals and associated drainage improvements.
C.
Site design using low impact development techniques. The post-construction stormwater plan shall demonstrate the preferential consideration of low impact development (LID) techniques in order to minimize stormwater quality and quantity impacts from development. LID is a development site design strategy with a goal of maintaining or reproducing the site's pre-development hydrologic functions of storage, infiltration, and groundwater recharge, as well as the volume and rate of stormwater discharges. LID strategies use small-scale integrated and distributed management practices, including minimizing impervious surfaces, infiltrating stormwater close to its source, and preservation of permeable soils and native vegetation. LID techniques to consider include, but are not limited to, the following:
1.
Development shall be sited and designed to preserve the infiltration, purification, detention, and retention functions of natural drainage systems that exist on the site, to the maximum extent practicable. Drainage shall be conveyed from the developed area of the site in a non-erosive manner.
2.
Development shall minimize the creation of impervious surfaces (including pavement, sidewalks, driveways, patios, parking areas, streets, and roof-tops), especially directly connected impervious areas, to the maximum extent practicable. Directly connected impervious areas include areas covered by a building, impermeable pavement, and/or other impervious surfaces, which drain directly into the storm drain system without first flowing across permeable land areas (e.g., lawns)
3.
Development shall maintain or enhance, where appropriate and feasible, on-site infiltration of stormwater runoff, in order to preserve natural hydrologic conditions, recharge groundwater, attenuate run-off flow, and minimize transport of pollutants.
Alternative management practices shall be substituted where the Public Works Director has determined that infiltration BMPs may result in adverse impacts, including but not limited to where saturated soils may lead to geologic instability, where infiltration may contribute to flooding, or where regulations to protect groundwater may be violated.
4.
Development that creates new impervious surfaces shall divert stormwater runoff flowing from these surfaces into permeable areas in order to maintain, or enhance where appropriate and feasible, on-site stormwater infiltration capacity.
5.
To enhance stormwater infiltration capacity, development applicants shall use permeable pavement materials and techniques (e.g., paving blocks, porous asphalt, permeable concrete, and reinforced grass or gravel), where necessary to retain water or reduce the rate of runoff. Permeable pavements shall be designed so that stormwater infiltrates into the underlying soil, to enhance groundwater recharge and provide filtration of pollutants.
D.
Water quality and hydrology plan for developments of water quality concern. In addition to the information to be provided in the post-construction stormwater plan, applicants for "developments of water quality concern," shall submit a water quality and hydrology plan and be subject to the additional requirements listed below.
1.
"Developments of water quality concern" include the following:
a.
Housing developments of ten or more dwelling units, including, but not limited to, residential subdivisions.
b.
Developments that result in the creation, addition, or replacement of ten thousand square-feet or more of impervious surface area.
c.
Parking lots with five thousand square feet or more of impervious surface area, potentially exposed to stormwater runoff.
d.
Vehicle service facilities, including retail gasoline outlets, commercial car washes, and vehicle repair facilities.
e.
Industrial parks, commercial strip malls, or restaurants with five thousand square feet or more of impervious surface area.
f.
Commercial or industrial outdoor storage areas of five thousand square feet or more, or as determined by the county based on the use of the storage area, where used for storage of materials that may contribute pollutants to the storm drain system or coastal waters.
g.
Heavy industrial developments.
h.
Streets, roads, highways, and freeway construction of five thousand square feet or more of impervious surface area, but not including stand-alone pedestrian pathways, trails, and off-street bicycle lanes.
i.
All developments entailing the creation, addition, or replacement of two thousand five hundred square feet or more of impervious surface area, located within one hundred twenty-five feet of the ocean or a coastal waterbody (including estuaries, wetlands, rivers, streams, and lakes), or that discharge directly to the ocean or a waterbody (i.e., outflow from the drainage conveyance system is composed entirely of flows from the subject development or redevelopment site, and not commingled with flows from adjacent lands.)
2.
Additional Requirements for developments of water quality concern:
a.
Water quality and hydrology plan. The applicant for a development of water quality concern shall be required to submit a water quality and hydrology plan (WQHP), prepared by a California Professional Engineer, Professional Geologist or Engineering Geologist, or California Landscape Architect, which supplements the post-construction stormwater plan. The WQHP shall include calculations, per County standards, that estimate increases in pollutant loads and changes in stormwater runoff hydrology (i.e., volume and flow rate) resulting from the proposed development, and shall specify the BMPs that will be implemented to minimize post-construction water quality and hydrologic impacts. The WQHP shall also include operation and maintenance plans for post-construction treatment control BMPs. In the application and initial planning process, the applicant shall be required to submit for approval a preliminary WQHP, and prior to issuance of a building permit the applicant shall submit a final WQHP for approval by the County Engineer.
b.
Selection of structural treatment control BMPs. If the County determines that the combination of site design and source control BMPs is not sufficient to protect water quality and coastal waters, a structural treatment control BMP (or suite of BMPs) shall also be required. Developments of water quality concern are presumed to require treatment control BMPs to meet the requirements of the coastal land use plan and state and federal water quality laws, unless the water quality and hydrology plan demonstrates otherwise.
The water quality and hydrology plan for a development of water quality concern shall describe the selection of treatment controls BMPs. Applicants shall first consider the treatment control BMP, or combination of BMPs, that is most effective at removing the pollutant(s) of concern, or provide a justification if that BMP is determined to be infeasible.
c.
Eighty-fifth percentile design standard for treatment control BMPs. For post-construction treatment of stormwater runoff in developments of water quality concern, treatment control BMPs (or suites of BMPs) shall be sized and designed to treat, infiltrate, or filter the amount of stormwater runoff produced by all storms up to and including the eighty-fifth percentile, twenty-four-hour storm event for volume-based BMPs, and/or the eighty-fifth percentile, one-hour storm event (with an appropriate safety factor of two or greater) for flow-based BMPs.
d.
Maintain pre-development hydrograph. In developments of water quality concern where changes in stormwater runoff hydrology (i.e., volume and flow rate) may result in increased potential for streambank erosion, downstream flooding, or other adverse habitat impacts, hydrologic control measures (e.g., stormwater infiltration, detention, harvest and re-use, and landscape evapotranspiration) shall be implemented in order to ensure that the pre- and post-project runoff hydrographs match within ten percent for a two-year return frequency storm.
5.
Content. The water quality and hydrology plan shall contain the following:
a.
Site design, source control, and treatment control BMPs that will be implemented to minimize post-construction water quality and hydrologic impacts.
b.
All of the information required in sub-section A for the post-construction stormwater plan.
c.
Pre-development stormwater runoff hydrology (i.e., volume and flow rate) from the site.
d.
Expected post-development stormwater runoff hydrology (i.e., volume and flow rate) from the site, with all proposed non-structural and structural BMPs in place.
e.
Measures to infiltrate or treat runoff from impervious surfaces (including roads, driveways, parking structures, building pads, roofs, and patios) on the site, and to discharge the runoff in a manner that avoids potential adverse impacts. Such measures may include, but are not limited to, structural treatment control BMPs including biofilters, grassy swales, on-site de-silting basins, detention ponds, or dry wells.
f.
A description of how the BMPs (or suites of BMPs) have been designed to infiltrate and/or treat the amount of storm water runoff produced by all storms up to and including the eighty-fifth percentile, twenty-four-hour storm event for volume-based BMPs, and/or the eighty-fifth percentile, one-hour storm event (with an appropriate safety factor of two or greater) for flow-based BMPs.
g.
Appropriate structural post-construction Treatment Control BMPs selected to remove the specific runoff pollutants generated by the development, using processes such as gravity settling, filtration, biological uptake, media adsorption, or any other physical, chemical, or biological process.
h.
A long-term plan and schedule for the monitoring and maintenance of all structural Treatment Control BMPs. All structural BMPs shall be inspected, cleaned, and repaired as necessary to ensure their effective operation for the life of the development. Owners of these devices shall be responsible for ensuring that they continue to function properly, and additional inspections should occur after storms as needed throughout the rainy season. Repairs, modifications, or installation of additional BMPs, as needed, shall be carried out prior to the next rainy season.
E.
Best management practices (BMPs); selection and incorporation.
1.
All development shall incorporate effective site design and long-term post-construction source control BMPs, as necessary to minimize adverse impacts to water quality and coastal waters resulting from the development, to the maximum extent practicable. BMPs that protect post-construction water quality and minimize increases in runoff volume and rate shall be incorporated as necessary in the project design of developments in the following order of priority:
a.
Site design BMPs: Project design features that reduce the creation or severity of potential pollutant sources, or reduce the alteration of the project site's natural stormwater flow regime. Examples are minimizing impervious surfaces, preserving native vegetation, and minimizing grading.
b.
Source control BMPs: Methods that reduce potential pollutants at their sources and/or avoid entrainment of pollutants in runoff, including schedules of activities, prohibitions of practices, maintenance procedures, managerial practices, or operational practices. Examples are covering outdoor storage areas, use of efficient irrigation, and minimizing the use of landscaping chemicals.
c.
Treatment control BMPs: Systems designed to remove pollutants from stormwater, by simple gravity settling of particulate pollutants, filtration, biological uptake, media adsorption, or any other physical, biological, or chemical process. Examples are vegetated swales, detention basins, and storm drain inlet filters.
2.
The selection of BMPs shall be guided by the California Stormwater Quality Association (CAS-QA) Stormwater BMP Handbooks dated January 2003 (or the current edition), or an equivalent BMP manual that describes the type, location, size, implementation, and maintenance of BMPs suitable to address the pollutants generated by the development and specific to a climate similar to Del Norte County's. Caltrans' 2007 "Storm Water Quality Handbook: Project Planning and Design Guide" (or the current edition) may also be used to guide design of construction-phase BMPs. Additional guidance on BMPs is available from the state water resources and water quality boards, the U.S. Environmental Protection Agency, regional entities such as the Bay Area Stormwater Management Agencies Association's (BASMAA) "Start at the Source: Design Guidance Manual for Stormwater Quality Protection," and/or as may be developed from time to time with technological advances in water quality treatment.
3.
Where BMPs, are required, BMPs shall be selected that have been shown to be effective in reducing the pollutants typically generated by the proposed land use. The strategy for selection of appropriate BMPs to protect water quality and coastal waters shall be guided by Tables 17.84B-1 through 3, below, or equivalent tables which list pollutants of concern and appropriate BMPs for each type of development or land use.
(Ord. of 2-22-2011(1))
§ 17.84B.040 Supplementary findings.
In addition to the findings for approval or conditional approval of a coastal development permit, development authorization, or other entitlement as required by Section 17.84.033, the following supplementary findings, based on factual evidence, shall be made for new development or uses having potential impacts to the quality of coastal waters:
A.
Generally. All approved development will be, or has been conditioned to be, consistent with the development standards of Section 17.84B.050, as applicable.
(Ord. of 2-22-2011(1))
§ 17.84B.050 Development standards.
A.
Development shall be undertaken in accordance with the approved erosion and stormwater control final plans and/or water quality management plan. Any proposed changes to the approved final plans shall be reported to the director. No changes to the approved final plans shall occur without an amendment to the coastal development permit, or equivalent, unless the director determines that no amendment is legally required.
Table 17.84B-1: Pollutants Generated by Development Category | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Pollutants generated by various development categories include, but are not limited to: | |||||||||
Development Categories | Sediments | Nutrients | Heavy Metals | Organic Compounds | Trash and Debris | Oxygen Demanding Substances | Oil and Grease | Bacteria and Viruses | Pesticides |
Detached Residential Developments | X | X | X | X | X | X | X | ||
Attached Residential Developments | X | X | X | P(1) | P(2) | P | X | ||
Commercial Developments >100,000 ft2 | P(1) | P(1) | P(2) | X | P(5) | X | P(3) | P(5) | |
Automotive Service Facilities | X | X(4)(5) | X | X | |||||
Retail Gasoline Outlets | X | X(4)(5) | X | X | |||||
Restaurants | X | X | X | X | |||||
Hillside Developments | X | X | X | X | X | X | |||
Parking Lots | P(1) | P(1) | X | X | P(1) | X | P(1) | ||
Streets, Highways and Freeways | X | P(1) | X | X(4) | X | P(5) | X | ||
Notes: | |
|---|---|
X = anticipated P = potential | |
(1) | A potential pollutant if landscaping exists on-site |
(2) | A potential pollutant if the project includes uncovered parking areas |
(3) | A potential pollutant if land use involves food or animal waste products |
(4) | Including petroleum hydrocarbons |
(5) | Including solvents |
Table adapted from the city of Carpinteria's Water Quality Protection Ordinance. | |
Table 17.84B-1: Pollutants Generated by Development Category | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Pollutants generated by various development categories include, but are not limited to: | |||||||||
Development Categories | Sediments | Nutrients | Heavy Metals | Organic Compounds | Trash and Debris | Oxygen Demanding Substances | Oil and Grease | Bacteria and Viruses | Pesticides |
Detached Residential Developments | X | X | X | X | X | X | X | ||
Attached Residential Developments | X | X | X | P(1) | P(2) | P | X | ||
Commercial Developments >100,000 ft2 | P(1) | P(1) | P(2) | X | P(5) | X | P(3) | P(5) | |
Automotive Service Facilities | X | X(4)(5) | X | X | |||||
Retail Gasoline Outlets | X | X(4)(5) | X | X | |||||
Restaurants | X | X | X | X | |||||
Hillside Developments | X | X | X | X | X | X | |||
Parking Lots | P(1) | P(1) | X | X | P(1) | X | P(1) | ||
Streets, Highways and Freeways | X | P(1) | X | X(4) | X | P(5) | X | ||
Notes: | |
|---|---|
X = anticipated P = potential | |
(1) | A potential pollutant if landscaping exists on-site |
(2) | A potential pollutant if the project includes uncovered parking areas |
(3) | A potential pollutant if land use involves food or animal waste products |
(4) | Including petroleum hydrocarbons |
(5) | Including solvents |
Table adapted from the city of Carpinteria's Water Quality Protection Ordinance. | |
Table 3. Treatment Control BMP Efficiency for Pollutants of Concern(1) | |||||||
|---|---|---|---|---|---|---|---|
Efficiency of Treatment Control BMP categories for removal of pollutants of concern include, but are not limited to: | |||||||
Pollutants of Concern | Biofilters | Detention Basins | Infiltra-tion Basins(2) | Wet Ponds or Wetlands | Drainage Inserts | Filtration | Hydro-dynamic Separator Systems(3) |
Sediment | M | H | H | H | L | H | M |
Nutrients | L | M | M | M | L | M | L |
Heavy Metals | M | M | M | H | L | H | L |
Organic Compounds | U | U | U | U | L | M | L |
Trash and Debris | L | H | U | U | M | H | M |
Oxygen Demanding Substances | L | M | M | M | L | M | L |
Bacteria | U | U | H | U | L | M | L |
Oil and Grease | M | M | U | U | L | H | L |
Pesticides | U | U | U | U | L | U | L |
Notes: | |
|---|---|
L = Low removal efficiency for this pollutant | |
M = Medium removal efficiency for this pollutant | |
H = High removal efficiency for this pollutant | |
U = Unknown removal efficiency for this pollutant | |
(1) | The County is encouraged to periodically assess the performance characteristics of these BMPs to update this table. |
(2) | Includes trenches and permeable pavement |
(3) | Also known as hydrodynamic devices and baffle boxes |
Sources: Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters (1993), National Stormwater Best Management Practices Database (2001), and Guide for BMP Selection in Urban Developed Areas (2001) | |
Table adapted from the city of Carpinteria's Water Quality Protection Ordinance. | |