§ 153.043  STORMWATER POLLUTION PREVENTION PLANS (SWPPPs).
   (A)   Stormwater pollution prevention plan framework.
      (1)   A SWPPP must be prepared as part of the submission of any drainage plan.
         (a)   At least one SWPPP must be developed for each construction project covered by this plan, and a licensed engineer must prepare such SWPPP.
         (b)   For projects that disturb more than one acre, the SWPPP must be prepared, amended when necessary, certified and stamped by a qualified individual who is licensed as listed in § 153.008.
      (2)   The SWPPP must:
         (a)   Identify all potential sources of pollution that may reasonably be expected to affect the quality of stormwater discharges from the construction site;
         (b)   Describe practices to be used to reduce pollutants in stormwater discharges from the construction site; and
         (c)   Assure compliance with the terms and conditions of the town's water quality letter of approval, when properly implemented.
      (3)   Once a definable area has been finally stabilized, the permittee may mark this on the SWPPP, and no further SWPPP or inspection requirements apply to that portion of the site (e.g., earth-disturbing activities around one of three buildings in a complex are done and the area is finally stabilized, one mile of a roadway or pipeline project is done and finally stabilized, and the like).
      (4)   The permittee must implement the SWPPP as written from commencement of construction activity until final stabilization is complete.
   (B)   Allowable non-stormwater discharges.  The following non-stormwater discharges are authorized, provided the non-stormwater component of the discharge is in compliance with § 153.043(E), Management of non-stormwater discharges allowed under § 153.042(B):
      (1)   Discharges from firefighting activities;
         (2)   Fire hydrant flushings;
         (3)   Waters used to wash vehicles, where detergents are not used;
         (4)   Water used to control dust;
         (5)   Potable water, including uncontaminated water line flushings;
         (6)   Routine external building wash down that does not use detergents;
         (7)   Pavement wash waters, where spills or leaks of toxic or hazardous materials have not occurred (unless all spilled material has been removed), and where detergents are not used;
         (8)   Uncontaminated air conditioning or compressor condensate;
         (9)   Uncontaminated ground water or spring water;
         (10)   Foundation or footing drains, where flows are not contaminated with process materials such as solvents;
         (11)   Uncontaminated excavation dewatering;
         (12)   Landscape irrigation.
   (C)   SWPPP contents:  site and activity description.
      (1)   The SWPPP must identify all operators for the project site, and the areas of the site over which each operator has control.
      (2)   The SWPPP must describe the nature of the construction activity, including:
         (a)   The intended sequence and timing of planned major activities that disturb soils, such as clearing and grubbing, initial and final grading, and cut and fill activities at the site;
         (b)   Estimates of the total area expected to be disturbed by excavation, grading, or other construction activities, including dedicated off-site borrow and fill areas; and
         (c)   A general location map (e.g., USGS quadrangle map, a portion of a city or county map, or other map) with enough detail to identify the location of the construction site and surface waters of the state within one mile of the site.
      (3)   The SWPPP must contain a legible site map, showing the entire site, identifying:
         (a)   Direction(s) of stormwater flow and approximate slopes anticipated after major grading activities;
         (b)   Locations of off-site material, waste, borrow or construction equipment storage areas, excluding roll-off containers;
         (c)   Locations of all surface waters of the state (including wetlands);
         (d)   Locations where stormwater discharges to a surface water; and
         (e)   Areas where final stabilization has been accomplished and no further construction-phase permit requirements apply.
      (4)   The SWPPP must describe and identify the location and description of any stormwater discharge associated with industrial activity other than construction at the site. This includes stormwater discharges from dedicated asphalt plants and dedicated concrete plants that are covered by this permit.
   (D)   SWPPP contents:  controls to reduce pollutants.
      (1)   The SWPPP must include a description of all pollution control measures (i.e., BMPs) that will be implemented as part of the construction activity to control pollutants in stormwater discharges. For each major activity identified in the project description, the SWPPP must clearly describe control measures necessary to comply with this chapter and applicable laws and regulations, the general sequence during the construction process in which the measures will be implemented, and which operator is responsible for the control measure's implementation.
      (2)   The SWPPP must include a description of interim and permanent stabilization practices for the site, including a schedule of when the practices will be implemented. Site plans should ensure that existing vegetation is preserved where possible, and that disturbed portions of the site are stabilized.
      (3)   For sites with stormwater discharges to receiving waters listed as impaired in South Carolina's 303(d) List of Impaired Waters, the following requirements apply:
         (a)   If a total maximum daily load (TMDL) that is applicable to stormwater construction discharges has been established and is in effect, then:
            1.   SWPPP measures or controls that are consistent with the assumptions and requirements of such TMDL must be incorporated into the drainage plan; and
            2.   The SWPPP must incorporate any conditions applicable to project discharges necessary for consistency with the assumptions and requirements of such TMDL; and
            3.   If a specific wasteload allocation has been established that would apply to project discharges, the SWPPP must incorporate that allocation and implement necessary steps to meet that allocation.
         (b)   If a TMDL has specified a general wasteload allocation applicable to construction stormwater discharges, but no specific requirements for construction sites have been identified in the TMDL, then:
            1.   DHEC consultation is required to confirm that adherence to a SWPPP that meets the requirements of this chapter will be consistent with the TMDL.
            2.   Where a TMDL has not specified a wasteload allocation applicable to construction stormwater discharges, but has not specifically excluded these discharges, adherence to a SWPPP that meets the requirements of this chapter will generally be assumed to be consistent with the approved TMDL.
            3.   If the TMDL specifically precludes such discharges, the town will not approve the project unless DHEC issues a separate stormwater permit for the project.
         (c)   If a TMDL has not been established or is not in effect, the SWPPP must not allow stormwater discharges that will contribute to the violations of the water quality standards. To accomplish this, the applicant must:
            1.   First determine whether or not a project discharge may contain any pollutant that has caused the impairment.
            2.   If project stormwater discharges will not contain the pollutant(s) of concern, no additional requirements are necessary.
            3.   If project discharges will contain the pollutant(s) of concern, the BMPs selected for the site must be carefully evaluated and their performance assessed to ensure that stormwater discharges will not contribute to or cause a violation of water quality standards.
            4.   For projects that disturb 25 acres or more, the SWPPP must contain a written quantitative and qualitative assessment that the BMPs selected will control project stormwater discharges so that they will not contribute to or cause a violation of water quality standards.
            5.   For more information, please see the DHEC publication entitled “Antidegradation for Activities Contributing to Nonpoint Source Pollution to Impaired Waters,” which can be downloaded at the following DHEC website:  www.scdhec.gov/eqc/water/pubs/antidegnps.pdf.
            6.   A copy of the most current 303(d) List of Impaired Waters can be obtained from:
               Water Quality Division
               Bureau of Water SC DHEC
               2600 Bull Street
               Columbia, SC 29201
               or downloaded at the following DHEC website:  www.scdhec.gov/water/html/tmdl.html.
      (4)   The following records must be maintained as part of the SWPPP:
         (a)   Dates when major grading activities occur;
         (b)   Dates when construction activities temporarily or permanently cease on a portion of the site. (Note: TEMPORARILY CEASING CONSTRUCTION means ceasing construction on a portion of the site for more than 14 days. A PORTION OF THE SITE means, but is not limited to, a PORTION OF THE SITE with dedicated controls. Where stabilization by the 14th day is precluded by snow cover or frozen ground conditions, stabilization measures must be initiated as soon as practicable. Where construction activity on a portion of the site is temporarily ceased, and earth-disturbing activities will be resumed within 14 days, temporary stabilization measures do not have to be initiated on that portion of the site); and
         (c)   Dates when stabilization measures are initiated.
         (d)   Electronic storage of the above mentioned information is acceptable, provided that it is referenced in the SWPPP and it is readily available.
      (5)   The SWPPP must include a description of all post-construction stormwater management measures that will be installed during the construction process to control pollutants in stormwater discharges after construction operations have been completed.
      (6)   Structural measures should be placed on upland soils to the degree practicable. Such measures must be designed and installed in compliance with applicable federal, local or state requirements.
      (7)   The SWPPP must describe measures to prevent the discharge of building or other similar materials to surface waters of the state, except as authorized by a permit issued under § 404 of the Clean Water Act. See also § 153.043 (L)(3).
      (8)   The SWPPP must describe measures to minimize, to the extent practicable, off-site vehicle tracking of sediments onto paved surfaces and the generation of dust.
      (9)   The SWPPP must include a description of construction and waste materials expected to be stored on-site, with updates as appropriate. The SWPPP must also include a description of controls, including storage practices such as roll-off containers, to minimize exposure of the materials to stormwater, and spill prevention and response practices.
      (10)   The SWPPP must include a description of pollutant sources from areas other than construction (including stormwater discharges from dedicated asphalt plants and dedicated concrete plants), and a description of controls and measures that will be implemented at those sites to minimize pollutant discharges. If these areas are located off the construction area on property not owned by the owner of the project, they can be either included in the SWPPP for the construction site, with the owner of the dedicated facility being a co-permittee under the permit issued by the town for the project; or the owner of the dedicated facility can obtain:  (a) their own permit coverage to build the dedicated facility; and (b) their own coverage under the Stormwater General Permit for Industrial Activity, Permit #SCR000000, or other appropriate permit. The method(s) selected to deal with dedicated facility areas must be addressed in the SWPPP.
   (E)   Management of non-stormwater discharges allowed under § 153.042(B).
      (1)   The SWPPP must identify all allowable sources of non-stormwater discharges, except for flows from firefighting activities, which are combined with stormwater discharges associated with construction activity at the site.
      (2)   Non-stormwater discharges should be eliminated or reduced to the extent feasible.
      (3)   The SWPPP must identify and ensure the implementation of appropriate pollution prevention measures for the non-stormwater component(s) of the discharge.
   (F)   Maintenance of controls.
      (1)   All erosion and sediment control measures and other protective measures identified in the SWPPP must be maintained in effective operating condition. If site inspections identify BMPs that are not operating effectively, maintenance must be performed as soon as practical or as reasonably possible, and before the next storm event whenever practicable, to maintain the continued effectiveness of stormwater controls.
      (2)   If existing BMPs need to be modified or if additional BMPs are necessary to comply with the requirements of this permit and/or South Carolina’s water quality standards, implementation must be completed before the next storm event, whenever practicable. If implementation before the next storm event is impracticable, the situation must be documented in the SWPPP and alternative BMPs must be implemented as soon as reasonably possible.
      (3)   Sediment from sediment traps or sedimentation ponds must be removed as indicated in the SWPPP, or when the design capacity has been reduced by 50%, whichever occurs first.
   (G)   Copy of permit requirements.  Copies of the town water quality approval letter, the signed and certified notice of intent form that was submitted to DHEC, and the co-permittee certifications are required as part of the SWPPP. Also, upon receipt, a copy of the letter from the DHEC authorizing coverage under the DHEC construction general permit must also be included as a component of the SWPPP.
   (H)   Applicable state or federal programs.  The SWPPP must be consistent with all applicable federal or state requirements for soil and erosion control and stormwater management, including updates to the SWPPP as necessary to reflect any revisions to applicable federal or state requirements for soil and erosion control.
   (I)   Inspections.  The following inspection requirements duplicate SCDHEC's construction general permit and are included here to simplify compliance with both the town's and the DHEC's requirements.
      (1)   After construction begins, inspections must be conducted at a minimum in accordance with one of the two schedules listed below:
         (a)   At least once every seven calendar days, or
         (b)   At least once every 14 calendar days and within 24 hours of the end of a storm event of one-half inch or greater.
      (2)   Inspection frequency may be reduced to once every month if the entire site is temporarily stabilized.
      (3)   On a case-by-case basis, the town may require any permittee who has coverage under this program to conduct inspections on a more frequent basis than prescribed in this subsection. Examples
include, but are not limited to:  permittees who have compliance problems, and permittees whose sites’ stormwater discharges to environmentally sensitive waters (such as waters classified as outstanding resource waters, shellfish harvesting waters, and the like).
      (4)   Inspections must be conducted by qualified personnel, provided by the operator or cooperatively by multiple operators. QUALIFIED PERSONNEL means a person knowledgeable in the principles and practice of erosion and sediment controls, who possesses the skills to assess conditions at the construction site that could impact stormwater quality, and to assess the effectiveness of any sediment and erosion control measures selected to control the quality of stormwater discharges from the construction activity. This person must be either the preparer of the SWPPP or an individual who is under the direct supervision of the preparer of the approved SWPPP, and who meets the requirements in this paragraph, or an individual who has been certified through a construction site inspector certification course that has been approved by DHEC. Inspections may also be conducted by a person with a registration equivalent to the registration of the preparer of the SWPPP and who meets the qualifications of this paragraph, or an individual who is under the direct supervision of the person with an equivalent registration and who meets the requirements in this paragraph.
      (5)   Inspections must include all areas of the site disturbed by construction activity and areas used for storage of materials that are exposed to precipitation. Inspectors must look for evidence of, or the potential for, pollutants entering the stormwater conveyance system. Sedimentation and erosion control measures identified in the SWPPP must be observed to ensure proper operation. Discharge locations must be inspected to ascertain whether erosion control measures are effective in preventing violations to South Carolina's water quality standards, where accessible. Where discharge locations are inaccessible, nearby downstream locations must be inspected to the extent that such inspections are practicable. Locations where vehicles enter or exit the site must be inspected for evidence of off-site sediment tracking.
      (6)   Utility line installation, pipeline construction, and other examples of long, narrow, linear construction activities may limit the access of inspection personnel to the areas described above. Inspection of these areas could require that vehicles compromise temporarily or even permanently stabilized areas, cause additional disturbance of soils, and increase the potential for erosion. In these circumstances, controls must be inspected on the same frequencies as other construction projects, but representative inspections may be performed. For representative inspections, personnel must inspect controls along the construction site for one-quarter mile above and below each access point where a roadway, undisturbed right-of-way, or other similar feature intersects the construction site and allows access to the areas described above. The conditions of the controls along each inspected quarter mile segment may be considered as representative of the condition of controls along that reach extending from the end of the quarter mile segment to either the end of the next quarter mile inspected segment, or to the end of the project, whichever occurs first. Representative inspections must include any areas where stormwater discharges to environmental sensitive waters (such as waters classified as outstanding resource waters, shellfish harvesting waters, and the like).
      (7)   An inspection report must be completed for each inspection required above. At a minimum, the inspection report must include:
         (a)   The inspection date;
         (b)   Names, titles, and, if not previously given in an inspection report, the qualifications of personnel making the inspection;
         (c)   Weather information for the period since the last inspection (or since commencement of construction activity if the first inspection), including a best estimate of the beginning of each storm event, duration of each storm event, approximate amount of rainfall for each storm event (in inches), and whether any discharges occurred;
         (d)   Weather information and a description of any discharges occurring at the time of the inspection;
         (e)   Location(s) of discharges of sediment or other pollutants from the site;
         (f)   Location(s) of BMPs that need maintenance;
         (g)   Location(s) of BMPs that failed to operate as designed or proved inadequate for a particular location;
         (h)   Location(s) where additional BMPs are needed that did not exist at the time of inspection; and
         (i)   Corrective action required, including any changes to the SWPPP necessary and implementation dates.
         (j)   A record of each inspection and of any actions taken in accordance with this section must be retained as part of the SWPPP for at least three years from the date that permit coverage expires or is terminated. The report must be signed in accordance with of § 122.22 of S.C. Regulation 61-9
      (8)   For construction sites disturbing ten acres or more, a monthly report must be submitted to the town.
         (a)   The report must be signed in accordance with § 122.22 of S.C. Regulation 61-9.
         (b)   In lieu of submitting monthly reports, the reports may be stored electronically in a manner in which town personnel will have access to review this data, such as on a dedicated website to which town personnel will have unlimited access.
         (c)   Other forms of electronic storage of monthly reports may be utilized once arrangements have been made with the town.
      (9)   For construction sites that disturb less than ten acres, the town may require monthly reports to be submitted on either a project-by-project basis or an operator-by-operator basis.
      (10)   If the information required in this subsection is already included on the inspection forms, only copies of the inspection forms need to be submitted to the town. If the information required in this subsection is not included on the inspection form, then the monthly reports must include, at a minimum, the following additional information:
         (a)   A summary of the results of the inspections conducted during the month;
         (b)   A listing of all deficiencies noted during inspections, with the date each deficiency was noted;
         (c)   For each deficiency noted that required corrective action:
            1.   A listing of the name(s), address(es), and telephone number(s) of the party or parties responsible; and
            2.   A statement whether this deficiency was previously listed in a monthly report;
         (d)   A listing of the corrective actions that were taken to remedy any deficiencies noted, and the date each corrective action was completed;
         (e)   A statement on whether or not the SWPPP was updated to deal with any deficiencies noted; and
         (f)   A copy of each inspection conducted during the month attached in an appendix to the monthly report.
      (11)   For construction sites disturbing ten acres or more, in addition to the information required above, the first monthly report submitted after construction has started must include one copy of the co-permittee and contractor certifications. Subsequent monthly reports on construction sites that disturb ten acres or more must include copies of certifications for co-permittees and contractors added after construction has started. For each co-permittee and contractor certification submitted to the town, the preparer of the SWPPP, or someone with a registration equivalent to that of the preparer of the SWPPP, must certify that either an on-site or, when applicable, an off-site pre-construction conference was held with the co-permittee or contractor in accordance with this permit. This certification must give the date of the conference and the responsibilities of each co-permittee and contractor.
      (12)   For construction sites disturbing less than ten acres, the owners/operators may be required to submit the co-permittee and contractor certifications on a case-by-case basis. When the owner/operator is required to submit the co-permittee and contractor certifications, the preparer of the SWPPP, or someone with a registration equivalent to that of the preparer of the SWPPP, must certify that either an on-site or an  off-site pre-construction conference was held with the co-permittees and contractors in accordance with this permit. This certification must give the date of the conference and the responsibilities of each co-permittee and contractor.
      (13)   Each monthly report with one copy must be submitted to the Town Stormwater Program Manager on or before 28th day of the month following the reporting period. For example, the monthly report for July 2007 is due after July 31, 2007, and on or before August 28, 2007.
      (14)   Until construction starts, the monthly report may just state that construction activity has not started.
      (15)   When required, monthly reports must be submitted until the notice of termination is submitted to DHEC. When the notice of termination is submitted, it must contain a signed statement by the preparer of the SWPPP, or a person with a registration equivalent to that of the preparer of the SWPPP, that all work was completed to the best of his or her knowledge and belief, in accordance with the approved SWPPP and this CGP. For projects disturbing more than one acre, the certifying person's knowledge and belief must be based on the results of the periodic inspections conducted by the preparer of the SWPPP (or a person with an equivalent registration), or by a qualified individual under his or her direct supervision in accordance with this CGP, or by an individual certified through a construction site inspector certification course that has been approved by DHEC.
      (16)   Copies of inspection forms and monthly reports must be submitted to the Stormwater Program Manager at the following address:
      Town of Mount Pleasant
      P.O. Box 745
      Mount Pleasant, SC 29465
or to a designated town email address, when available.
   (J)   Maintaining an updated plan.
      (1)   The SWPPP, including the site map, must be amended whenever there is a change in design, construction, operation or maintenance at the construction site that will result in discharges that will cause, have the reasonable potential to cause, or contribute to violations to South Carolina's water quality standards.
      (2)   The SWPPP must be amended if, during inspections or investigations by site staff or by local, state or federal officials, it is determined that the SWPPP is ineffective in either eliminating, when reasonably possible, or significantly minimizing pollutants in stormwater discharges from the construction site.
      (3)   Based on the results of an inspection, the SWPPP must be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP must be completed within seven calendar days following the inspection. Implementation of these additional or modified BMPs must be accomplished as described in this section.
   (K)   Signature, plan review and making plans available.
      (1)   A copy of the SWPPP (including a copy of the permit), DHEC notice of intent, and construction general permit coverage letter from DHEC must be retained at the construction site (or other location easily accessible during normal business hours to:  DHEC, EPA or town officials) from the date of commencement of construction activities to the date of final stabilization.
      (2)   If you have day-to-day operational control over SWPPP implementation, you must have a copy of the SWPPP available at a central location on-site for the use of all those identified as having responsibilities under the SWPPP whenever they are on the construction site. If an on-site location is unavailable to store the SWPPP when no personnel are present, notice of the plan's location must be posted near the main entrance at the construction site.
      (3)   For linear construction of roads or utilities (such as roads built by the South Carolina Department of Transportation and utility construction, including electrical power lines, gas lines, main sewer trunk lines, and water distribution lines that are not part of a development), neither of which are a part of a subdivision or other type of development project, the updated copies of the approved SWPPP must be sent to the town in situations where it is not practical to have the approved SWPPP on location. For South Carolina Department of Transportation Projects where there is no construction trailer on site, the SWPPP may be kept in the office of the SC DOT resident engineer.
      (4)   SWPPPs must be made available upon request by town. The copy of the SWPPP that is required to be kept on-site or locally available must be made available, in its entirety, to the town for review and copying at the time of an on-site inspection.
      (5)   All SWPPPs must be signed and certified in accordance with § 122.22 of S.C. Regulation 61-9.
   (L)   Management practices.
      (1)   All control measures must be properly selected, installed and maintained in accordance with any relevant manufacturer specifications and good engineering practices. If periodic inspections or other information indicate a control has been used inappropriately or incorrectly, the operator must replace or modify the control for site situations as soon as practicable.
      (2)   If sediment escapes the construction site, off-site accumulations of sediment must be removed at a frequency sufficient to minimize off-site impacts, unless:  access to the off-site property cannot be reasonably obtained from the property owner; or DHEC agrees that it is appropriate to leave the off-site accumulations in place.
      (3)   Litter, construction debris, oils, fuels, building products with significant potential for impact (such as stockpiles of freshly treated lumber), and construction chemicals that could be exposed to stormwater must be prevented from becoming a pollutant source in stormwater discharges.
      (4)   Except as provided below, stabilization measures must be initiated as soon as practicable in portions of the site where construction activities have temporarily or permanently ceased, but in no case more than 14 days after the construction activity in that portion of the site has temporarily or permanently ceased.
         (a)   Where stabilization by the 14th day is precluded by snow cover or frozen ground conditions, stabilization measures must be initiated as soon as practicable.
         (b)   Where construction activity on a portion of the site is temporarily ceased, and earth-disturbing activities will be resumed within 14 days, temporary stabilization measures do not have to be initiated on that portion of the site.
      (5)   A combination of sediment and erosion control measures is required to achieve maximum pollutant removal.
         (a)   Sediment basins.
            1.   For common drainage locations that serve an area with ten or more acres disturbed at one time, a temporary (or permanent) sediment basin that provides storage for a calculated volume of runoff from the drainage area from at least a ten-year, 24-hour storm, or equivalent control measures, must be provided, where attainable, until final stabilization of the site.
            2.   Where no such calculation has been performed, a temporary (or permanent) sediment basin providing at least 3,600 cubic feet of storage per acre drained, or equivalent control measures, must be provided, where attainable, until final stabilization of the site.
            3.   When computing the number of acres draining into a common location, it is not necessary to include flows from off-site areas and flows from on-site areas that are either undisturbed or have undergone final stabilization, where such flows are diverted around both the disturbed area and the sediment basin.
            4.   In determining whether installing a sediment basin is attainable, the operator may consider factors such as site soils, slope, available area on-site, and the like. In any event, the operator must consider public safety as a design factor for the sediment basin, and alternative sediment controls must be used where site limitations would preclude a safe design.
         (b)   Sediment controls for drainage locations serving ten or more acres.  For drainage locations that serve ten or more disturbed acres at one time, and where a temporary sediment basin or equivalent controls are not attainable, smaller sediment basins and/or sediment traps should be used. Silt fences, vegetative buffer strips, or a combination of sediment controls that are equivalent to sediment basins and/or sediment traps are required for all down-slope boundaries (and for those side-slope boundaries deemed appropriate as dictated by individual site conditions).
         (c)   Sediment controls for drainage locations serving less than ten acres.  For drainage locations serving less than ten acres, smaller sediment basins and/or sediment traps should be used.
            1.   At a minimum, silt fences, vegetative buffer strips, or equivalent sediment controls are required for all down-slope boundaries (and for those side-slope boundaries deemed appropriate, as dictated by individual site conditions) of the construction area, unless a sediment basin providing storage for a calculated volume of runoff from at least a ten-year, 24-hour storm, or at least 3,600 cubic feet of storage per acre drained, is provided.
            2.   If a basin is not provided, each structural control used must be designed to handle the entire drainage area it serves.
         (d)   Increased requirements.  On a case-by-case or watershed-by-watershed basis, the town may require the use of a larger storm event and/or a larger storage volume when designing sediment basins.
      (6)   Velocity dissipation devices must be placed at discharge locations and along the length of any outfall channel, to provide a non-erosive flow velocity from the structure to a water course so that the natural physical and biological characteristics and functions are maintained and protected (e.g., no significant changes in the hydrological regime of the receiving water).
(Ord. 07045, passed 8-14-07)