SC - City of Charleston: TECHNICAL REVIEW COMMITTEE

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TECHNICAL REVIEW COMMITTEE

4.
Acceptance and Dedication of Daniel Island, Parcel S, Tract 2- a portion of Farr Street (50' RM/, 1679 LF) a. Title to Real Estate b. Affidavit for Taxable or Exempt Transfers c. Exclusive Stormwater Drainage Easement Agreement d. Plat

No additional detail provided

Tagged Passions:streets, zoning, property, easement, and stormwater

E.
Temporary Encroachments Approved by The Department of Public Service (For information only)

No additional detail provided

Tagged Passions:encroachment

1.
122 Spring St. - 124 Spring, LLC - Installing 40 X 18 right angled sign above the public right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

2.
45 1/2 Spring St. -Warehouse - Installing 36 X 12 right angled sign above the public right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

3.
457 Spring Hollow Dr. - Installing driveway encroaching into City drainage easement. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment, easement, and stormwater

4.
544 Yellow Tower- Installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:cell tower, Cell tower, and encroachment

5.
967 Foliage Ln. - Installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

6.
1167 Elliotts Cut Dr. - Installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

7.
1519 Charming Nancy Rd. - Installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

8.
1659 Emmets Rd. - Installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

Department of Public Service 2 George Street Charleston, South Carolina 29401 Tel: (843) 724-3754 Fax: (843) 973-7261

Tagged Passions:streets

10.
1954 Bellona St. - Installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

11.1608 Juliana St. - Transfer installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

12.1620 Juliana St. - Transfer installing irrigation encroaching into City right-of-way. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment

13.
2556 Daniel Island Dr. - Transfer installing 6ft wood fence and drain basin encroaching into City drainage easement. This encroachment is temporary. Approved September 20, 2019.

No additional detail provided

Tagged Passions:encroachment, easement, and stormwater

F.
Stormwater Management Deparbnent Update

No additional detail provided

Tagged Passions:stormwater

1.
Stormwater Fee - Assistance Program Discussion

No additional detail provided

Tagged Passions:program and stormwater

2.
Stormwater Design Standard Manual Update Discussion

No additional detail provided

Tagged Passions:stormwater

3.
Dupont Wappoo Project Area Recommendations Discussion

No additional detail provided

4.
An ordinance amending Chapter 27, Stormwater Management and Flood Control, of the Code of the City of Charleston, by amending the definitions in the Flood Hazard Prevention and Control Requirements in Article 11, Division 3, Section 27-103 to add a new definition for market value for the purpose of making final determinations of substantial damage and substantial improvement under this Division allowing the appraised value of a structure to be used in place of the assessed value. (AS AMENDED) (Requested by Councilmember Perry K. Waring)

No additional detail provided

Tagged Passions:ordinance, market, flooding, and stormwater

5.
Church Creek Task Force Discussion

6. Project Update

Tagged Passions:church

7.
Floodplain Management Update

No additional detail provided

8.
Update on Spring/Fishburne and Low Battery STIB grant applications

No additional detail provided

Tagged Passions:grant

Department of Public Service 2 George Street Charleston, South Carolina 29401 Tel: (843) 724-3754 Fax: (843) 973-7261

Tagged Passions:streets

CITY OF CHARLESTON

STORMWATER DESIGN STANDARDS MANUAL

AUGUST 2019 Prepared for:
Tagged Passions:stormwater

CITY OF CHARLESTON DEPARTMENT OF STORMWATER MANAGEMENT

Tagged Passions:stormwater

2
GEORGE STREET CHARLESTON, SOUTH CAROLINA 29401

Prepared by: AECOM 4016 SALT POINTE PARKWAY
Tagged Passions:streets

NORTH CHARLESTON, SOUTH CAROLINA 29405

Project No. 60552163

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 i
Tagged Passions:stormwater

City of Charleston Signature Page1 I hereby certify that I have examined this Stormwater Design Standards Manual and,2 being familiar with the South Carolina Department of Health and Environmental Control3 (SCDHEC) National Pollutant Discharge Elimination System (NPDES) General Permit for4 Stormwater Discharges from Regulated Small Municipal Separate Storm Sewer5 Systems (MS4s) and the City of Charleston Department of Stormwater Management,6 attest that this Manual has been prepared in accordance with the applicable MS47 permit requirements. My signature below constitutes authorization for the commitment8 of resources necessary for implementation of the Manual.9

Tagged Passions:health, environment, and stormwater

10
11 12 13 14 15 16 17

Director, Department of Stormwater Management Date18
Tagged Passions:stormwater

19
City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 ii

Tagged Passions:stormwater

Contacts1 Phone Number Address

General Stormwater Questions
Tagged Passions:stormwater

(843) 724-3754 Fax: (843) 973-7261

No additional detail provided

2
George Street Suite 2100

Charleston, SC 29401 Stormwater Technical/Design Questions
Tagged Passions:streets and stormwater

(843) 724-3754 Fax: (843) 973-7261

No additional detail provided

2
George Street Suite 2100

Charleston, SC 29401 Stormwater Permitting (843) 724-3761 2 George Street
Tagged Passions:streets and stormwater

Suite 2100 Charleston, SC 29401

Building Inspections: Administration Plan Review

Services (843) 577-1685
Tagged Passions:services

2
George Street Ground Floor

Charleston, SC 29401
Tagged Passions:streets

Building Inspections: Inspection Services (843) 724-7441

Tagged Passions:services

2
George Street Ground Floor

Charleston, SC 29401 Building Inspections: Permit Center (843) 577-5550
Tagged Passions:streets

2
George Street Ground Floor

Charleston, SC 29401 2
Tagged Passions:streets

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 iii
Tagged Passions:stormwater

Record of Revisions1 Date Revision

June 2008 Draft Stormwater Design Standards Manual
Tagged Passions:stormwater

February 2009 Stormwater Design Standards Manual Draft Final

Tagged Passions:stormwater

January 2010 Stormwater Design Standards Manual - Final

Tagged Passions:stormwater

February 2011 Stormwater Design Standards Manual Updated Final

Tagged Passions:stormwater

March 2013 Stormwater Design Standards Manual Updated Final

Tagged Passions:stormwater

August 2014 Appendix Update

2019 Major Revision

2
This manual is intended to be a dynamic document. As design technology and criteria evolve3 and change or it becomes evident that additional measures are needed to ensure the public4 general welfare, this manual shall be amended with City Council s approval. This manual can5 also be found on the City of Charleston s website at https://www.charleston-sc.gov/.6

Tagged Passions:council, Technology, and technology

7
City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 iv Acknowledgements1 The development of the Stormwater Design Standards Manual represents the culmination of a2 cooperative, collaborative effort among the City of Charleston, the Stormwater Design3 Standards Task Force, and AECOM.4

Tagged Passions:development, Development, and stormwater

City of Charleston5 Mayor John Tecklenburg6 Council Member Peter7 Shahid8 Council Member Gary White9 Council Member Carol10 Jackson11 Matthew Fountain12 Tom O Brien13

Tagged Passions:council

Kinsey Holton14 Matt Blackwell15 Stephen Julka16 Steve Kirk17 Chris Morgan18 Katie McKain19 Tracy McKee20 Frank Newham21

The Stormwater Design Standards Task Force provided guidance and feedback on the content22 of this document, reviewed drafts, developed and participated in workshops, and engaged23 stakeholders. We would like to thank them for their enthusiasm, knowledge, experience, and24 commitment to the process.25
Tagged Passions:stormwater

26
Dianne Aghapour, Citizen at Large27 Jared T. Bramblett, Davis Floyd28 Andrew Todd Burke, HLA, Inc.29 Abraham Champagne, Clemson University30 Stuart Coleman, CC T31 Kelsey Gagnon, Berkeley County32 Jeannie Lewis, SCDHEC OCRM33 Bill McKenzie, Daniel Island Associates, LLC34 Betty Niermann, Seamon, Whiteside Associates35 Kirk Richards, SCDOT36 Jack Smith, Nelson Mullins37 Lisa Vandiver, Johns Island Community Association, NOAA38 Guinn Wallover, Clemson Extension, Ashley Cooper Stormwater Education Consortium39 Chris Wannamaker, Charleston County40 James L. Ward, College of Charleston41 Patrick Arnold, Charleston Homebuilder s Association42 Josh Dix, Charleston Trident Association of Realtors43

No additional detail provided

Tagged Passions:Clemson, university, education, and stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 v
Tagged Passions:stormwater

Table of Contents1 City of Charleston Signature Page .......................................................................................................................... i2 Contacts ............................................................................................................................................................................ ii3 Record of Revisions ..................................................................................................................................................... iii4 Acknowledgements ..................................................................................................................................................... iv5 Table of Contents .......................................................................................................................................................... v6 Acronyms and Abbreviations .................................................................................................................................. vi7 Definitions ........................................................................................................................................................................ ix8 Executive Summary ................................................................................................................................................. xxiii9

10
11

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 vi Acronyms and Abbreviations1 AASHTO American Association of State Highway and Transportation Officials2 AEP Annual Exceedance Probability3 AO Administrative Order4 ASCE American Society of Civil Engineers5 ASTM American Society of Testing and Materials6 BMP Best Management Practice7 CAA Construction Activity Application8 CAP Citizen Access Portal9 CEPSCI Certified Erosion Prevention and Sediment Control Inspector10 CFR Code of Federal Regulations11 CGP Construction General Permit12 City City of Charleston13 CPMSF Covenant for Permanent Maintenance of Stormwater Facilities14 CRS Community Rating System15 CSPR Certified Stormwater Plan Reviewer16 C-SWPPP Comprehensive Stormwater Pollution Prevention Plan17 CTWA Coastal Tidelands and Wetlands Act of 197718 CWA Clean Water Act19 CZC Coastal Zone Consistency20 CZMA (Federal) Coastal Zone Management Act (of 1972)21 CZMP Coastal Zone Management Plan22 DO Dissolved Oxygen23 EPA Environmental Protection Agency24 EPSC Erosion Prevention and Sediment Control25 FEMA Federal Emergency Management Agency26 FIPS Federal Information Processing Standard27 FIRM Flood Insurance Rate Map28 GI Green Infrastructure29 GIS Geographic Information System30 H:V Horizontal to Vertical31 HEC Hydrologic Engineering Center32 HEC-RAS Hydrologic Engineering Center s River Analysis System33 HOA Home Owners Association34 HSG Hydrologic Soil Group35 HSPF Hydrological Simulation Program Fortran36 HY8 Culvert Hydraulic Analysis Program37 ICPR Interconnected Pond Routing38 IGP Industrial General Permit39
Tagged Passions:construction, GIS, utility, industrial, Utility, union, transportation, program, emergency, water, insurance, environment, watershed, flooding, FEMA, and stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 vii LCP Larger Common Plan1 LID Low Impact Development2 LOS Level of Service3 MEP Maximum Extent Practicable4 MHHW Mean Higher High Water5 MS4 Municipal Separate Storm Sewer System6 NAD North American Datum7 NAVD North American Vertical Datum8 NFIP National Flood Insurance Program9 NGVD National Geodetic Vertical Datum10 NOAA National Oceanic and Atmospheric Administration11 NOI Notice of Intent12 NOT Notice of Termination13 NOV Notice of Violation14 NPDES National Pollutant Discharge Elimination System15 NRCS Natural Resources Conservation Service16 NURP National Urban Runoff Program17 NWS National Weather Service18 OCRM Ocean and Coastal Resource Management19 OSHA Occupational Safety and Health Administration20 OS-SWPPP On-site Stormwater Pollution Prevention Plan21 PCA South Carolina Pollution Control Act22 PDF Portable Document Format23 QLP Qualifying Local Program24 RCP Reinforced Concrete Pipe25 SC811 South Carolina 81126 SCDHEC South Carolina Department of Health and Environmental Control27 SCDOT South Carolina Department of Transportation28 SCS Soil Conservation Service29 SEDCAD Sediment Erosion Discharge by Computer Aided Design30 SEDPRO Sediment Erosion Discharge Program31 SFHA Special Flood Hazard Area32 SFR Single Family Residence33 SLR Sea Level Rise34 SMS4 Small Municipal Separate Storm Sewer System35 SMSRA South Carolina Stormwater Management and Sediment Reduction Act of 199136 SOP Standard Operating Procedure37 SPCC Spill Prevention, Control, and Countermeasure38 SRC Subdivision Review Committee39 SWAT Soil and Water Assessment Tool40
Tagged Passions:health, sewer, utility, Utility, public safety, transportation, subdivision, water, Conservation, insurance, environment, flooding, and stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 viii SWDSM Stormwater Design Standards Manual1 SWMM Stormwater Management Model2 SWMP Stormwater Management Plan or Stormwater Management Program3 SWPPP Stormwater Pollution Prevention Plan4 TMDL Total Maximum Daily Load5 TRC Technical Review Committee6 TSS Total Suspended Solids7 UOS Uniform Ordinance Summons8 USACE United States Army Corps of Engineers9 USDA United States Department of Agriculture10 USDOT United States Department of Transportation11 USGS United States Geological Survey12 WOTUS Waters of the United States13
Tagged Passions:ordinance, utility, Utility, water, military, and stormwater

14
City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 ix Definitions1 Words used in this manual shall have their customary meanings as determined by the standard2 dictionary definition except for the following specific words and terms that are herein defined3 or are otherwise defined in the City of Charleston s Stormwater Management Ordinance, City4 Code, authorizing regulations listed in Section 1.5, or in applicable Federal Emergency5 Management Agency (FEMA) regulations. The Department of Stormwater Management shall6 have the right to define or interpret any other word or term contained within this manual.7 Accommodate: water elevation not exceeding the crown of the pipe or culvert crossing under8 a roadway; coming within 12 inches of the top of the ditch or channel for the design9 storm; or encroaching on more than one-third of a travel lane for street drainage, curbs,10 and gutters for the design storm event.11

Tagged Passions:regulation, ordinance, streets, travel, utility, Utility, events, water, FEMA, and stormwater

Algal Bloom: the rapid increase in the population of algae in an aquatic system.12 Applicant: a person, firm, governmental agency, partnership, limited liability company, or any13

other entity who seeks to obtain approval under the requirements of Chapter 27 in the14 City of Charleston Stormwater Ordinance and who, in addition to the property owner or15 operator, will be responsible for the land disturbing activity(ies) and related maintenance16 thereof. The Applicant executes the necessary forms to obtain approval for a permit for17 a land disturbing activity.18
Tagged Passions:ordinance, property, and stormwater

Appropriate Plan Approval Authority: SCDHEC, local government, or conservation district19 that is responsible in a jurisdiction for review and approval of Stormwater Management20 and Erosion Prevention and Sediment Control Plans. This function shall be carried out21 by the City of Charleston.22

No additional detail provided

Tagged Passions:Conservation and stormwater

Bankfull Events: the flow condition where the highest stresses are applied to streambanks,23 causing streambank erosion and channel enlargement.24

Tagged Passions:events

Best Management Practice (BMP): any structural or non-structural measure or drainage25 facility used for the control of stormwater runoff, be it for quantity or quality control.26 BMPs also include schedules of activities, prohibitions of practices, maintenance27 procedures, treatment requirements, operating procedures, and other management28 practices to control site runoff, spillage or leaks, sludge or waste disposal, drainage29 from raw material storage, or measures that otherwise prevent or reduce the pollutant30 loading of receiving water(s).31

Brownfield: a formal industrial or commercial site where future use is affected by32 environmental contamination.33

Tagged Passions:facility, utility, industrial, Utility, procedure, water, environment, commercial, and stormwater

Building: any structure built for support, shelter, or enclosure for any occupancy or storage.34

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 x Certified Erosion Prevention and Sediment Control Inspector (CEPSCI): a person with the1 responsibility for conducting inspections during construction and maintenance2 inspections after the land disturbing activity is completed as certified by SCDHEC.3 Certified Stormwater Plan Reviewer (CSPR): a person with the responsibility for reviewing4 Stormwater Management and Erosion Prevention and Sediment Control Plans for the5 City as certified by SCDHEC.6 Channel: a stormwater conveyance open to the atmosphere flowing under the influence of7 gravity, including, but not limited to, natural waterways, canals, ditches, swales, and8 flumes.9
Tagged Passions:construction, zoning, watershed, and stormwater

City of Charleston Ordinance: stormwater regulations set forth in the Stormwater10 Management and Flood Control Ordinance, specifically Chapter 27, Article 1, of the City11 of Charleston Code of Ordinances; in addition to applicable sections of Chapter 54,12 Zoning Ordinance.13

Tagged Passions:regulation, ordinance, zoning, flooding, and stormwater

Clean Water Act (CWA): the federal Water Pollution Control Act (33 U.S.C. section 1251 et seq.)14 and any subsequent amendments thereto.15

No additional detail provided

Tagged Passions:utility, Utility, union, and water

Construction or Construction Activity: an activity involving clearing, grading, transporting,16 filling, or any other activity that causes land to be exposed to the danger of erosion, or17 that might create an alteration to an existing drainage way or other component of the18 City s stormwater management system or drainage facility.19

Construction Activity Application: the set of drawings, specifications, design calculations,20 Stormwater Pollution Prevention Plan (SWPPP), and other documents necessary to21 apply for a construction activity permit.22
Tagged Passions:construction, facility, grading, and stormwater

Contour: representative line on a topographic map connecting points of equal elevation.23 Covenants: the Covenants for Permanent Maintenance of Stormwater Facilities (CPMSF),24

which is a permanent maintenance agreement between the property Owner and the City25 of Charleston, for maintenance of permanent stormwater BMPs described in26 construction plans approved by the City, and any other permanent stormwater BMPs27 thereafter constructed on the Owner s property.28 Conveyance System: private and public drainage facilities other than sanitary sewers within29 the City s MS4 by which stormwater runoff may be conveyed to receiving waters, and30 includes but is not limited to roads, streets, constructed channels, storm drains, pipes,31 street gutters, inlets to storm drains or pipes, or catch basins.32

Tagged Passions:construction, sewer, streets, utility, Utility, water, property, and stormwater

Culvert: an enclosed symmetrical channel of comparatively short length installed to convey33 water from one side of an embankment to the other, typically under a roadway, and34 mainly used to divert stream or rainfall runoff to prevent erosion or flooding on35 roadways.36

Tagged Passions:utility, Utility, water, flooding, and stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xi Detention: the collection and storage of stormwater runoff in a surface or subsurface facility1 for subsequent controlled discharge to a conveyance system or receiving water.2 Detention Structure: a permanent stormwater management structure whose primary purpose3 is to temporarily store stormwater runoff and release the stored runoff at controlled4 rates.5 Development: any of the following actions undertaken by a person, a firm, a governmental6 agency, a partnership, a limited liability company, or any other individual or entity,7 without limitation:8 Division or subdivision of a lot, tract, parcel, or other divisions by plat or deed;9 Construction, installation, or alteration of land, a structure, impervious surface, or drainage10
Tagged Passions:construction, utility, development, Utility, zoning, subdivision, water, Development, property, commercial, rates, detention, and stormwater

facility;11 Clearing, scraping, grubbing, or otherwise significantly disturbing the soil, vegetation, mud,12

sand, or rock of a site; or13 Adding, removing, exposing, excavating, leveling, grading, digging, burrowing, dumping,14 piling, dredging, or otherwise disturbing the soil, vegetation, mud, sand, or rock of a site.15 Discharge: when used without a qualifier, refers to discharge of a pollutant as defined at16 South Carolina Water Pollution Control Permits Regulation 61-9, section 122.2.17 Ditch: a drainage channel in the earth created by natural or artificial means to convey surface18 and/or subsurface water, flowing continuously or intermittently. Ditches are generally19 smaller than those conveyances referred to as channels.20 Drainage: a general term applied to the removal of surface or subsurface water from a given21 area either by gravity via natural means or by systems constructed to remove water,22 and is commonly applied herein to surface water.23

Tagged Passions:regulation, facility, utility, solid waste, Utility, water, grading, and stormwater

Drainage Area: an area contributing stormwater runoff to a single point.24 Drainage Easement: the right of access of stormwater runoff from adjacent drainage basins25

into the drainage way within the defined easement as defined by Section 54-1051(i) Ord.26 No. 2018-031 11, 4-10-18.27

Tagged Passions:easement and stormwater

Drainage Facility: any component of the drainage system.28 Drainage System: the surface and/or subsurface system that collects and conveys29

stormwater and surface water, and includes watercourses, waterbodies, receiving30 waters, and wetlands.31
Tagged Passions:facility, utility, Utility, water, and stormwater

Easement: an authorization by a property owner to the general public, a corporation, or a32 certain person or persons for the use of any designated part of his property for a33 specific purpose, as defined by Ord. No. 2007-158, 2, 8-21-07; Ord. No. 2017-110, 34 1, 9-13-17). An easement is also defined in the Zoning Ordinance as the right of use for35

No additional detail provided

Tagged Passions:ordinance, zoning, property, and easement

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xii
Tagged Passions:stormwater

access granted on, above, under, or across a tract of land by the landowner to another1 person or entity (Section 54-1051(i) Ord. No. 2018-031 11, 4-10-18).2

Elevation: height in feet above a given known datum, such as NGVD29.3 Embankment or Fill: a deposit of soil, rock, or other material placed by man.4 Erosion: the general process by which soils or rock fragments are detached and moved by the5
Tagged Passions:grant

action of wind, water, ice, and gravity.6 Erosion Prevention: measures employed to prevent erosion including soil stabilization7

practices, limited grading, mulch, temporary or permanent cover, compost application,8 and construction phasing.9 Eutrophication: the process by which a body of water becomes enriched in nutrients that10 stimulate growth of aquatic plant life, usually resulting in the depletion of dissolved11 oxygen.12 Evapotranspiration: the process by which water is transferred from the land to the13 atmosphere by evaporation from the soil and other surfaces and by transpiration from14 plants.15 Final Stabilization: having 70 or more of the entire site with permanent coverage in good16 condition.17 Flood or Flooding: a temporary rise in the level of water that results in the inundation of areas18 not ordinarily covered by water. The types of flood events that occur in the City of19 Charleston are:20 Coastal (Tidal) Flooding: occurs during high tides and is not dependent on weather21 conditions. Frequency of tidal flooding increases with effects of sea level rise and moon22 phases.23 Extreme Event (Flash) Flooding: occurs when intense rainfall makes water rise quickly and24 flow at a high speed for a short amount of time.25 Fluvial (Riverine) Flooding: occurs when the capacity of a river s channel is exceeded as a26
Tagged Passions:construction, utility, Utility, events, water, watershed, flooding, plant, grading, and growth

result of intense or sustained rainfall across the catchment.27 Groundwater Flooding: occurs when the water table rises up to the surface during a28

prolonged wet period. Low lying areas, areas near aquifers, and properties with cellars or29 basements are more likely to experience groundwater flooding.30 Surface Flooding: occurs when the volume of rainfall is unable to drain away through the31 drainage systems or infiltrate into the land, and instead flows over land.32 Floodplain: an area of low-lying ground that may be submerged by floodwaters.33 Grading: the excavating, filling (including hydraulic fill), or stockpiling of earth material, or any34 combination thereof, including the land in its excavated or filled condition.35
Tagged Passions:utility, Utility, water, flooding, grading, and stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xiii
Tagged Passions:stormwater

Green Infrastructure: an adaptable term used to describe an array of materials, technologies,1 and practices that use natural systems or engineered systems that mimic natural2 processes to enhance overall environmental quality and provide utility services. As a3 general principal, green infrastructure techniques use soils and vegetation to infiltrate,4 evapotranspirate, and/or recycle stormwater runoff. Examples of green infrastructure5 include green roofs, porous pavement, rain gardens, and vegetated swales.6

No additional detail provided

Tagged Passions:utility, Utility, materials, services, environment, and stormwater

Green Spaces: an area of grass, trees, or other vegetation set apart for recreational or7 aesthetic purposes in an otherwise urban environment.8

Hydrologic Soil Group: a classification of soils based on the soil s runoff potential used by the9 Natural Resource Conservation Service.10 Illicit Discharge or Illegal Discharge: any activity that results in a discharge to the City of11 Charleston stormwater management system or drainage facility or receiving waters12 that is not composed entirely of stormwater except:13 Discharge pursuant to a NPDES permit (other than the NPDES permit for discharges from14 the City of Charleston MS4) and15 Discharges resulting from fire-fighting activities.16
Tagged Passions:facility, Conservation, environment, trees, recreation, and stormwater

Impaired Waters: water bodies with pollutant load exceeding the Total Maximum Daily Load17 level established by the State in which it is located and approved by the Environmental18 Protection Agency.19

Impervious surface: a surface that has been compacted or covered with a layer of material so20 that it is highly resistant to infiltration by water, including conventionally surfaced21 streets, roofs, sidewalks, parking lots, and other similar structures.22 Infiltration: the passage or movement of water through the soil profile.23 King Tide: the highest seasonal tides that occur each year.24 Land Disturbing Activity: any use of the land by any person that results in a change in the25 natural cover or topography that may cause erosion and contribute to sediment and26 alter the quality and quantity of stormwater runoff.27
Tagged Passions:streets, utility, Utility, water, Pedestrian, parking, and stormwater

Larger Common Plan (LCP): broadly defined as any announcement or piece of documentation28 (including a sign, public notice or hearing, sales pitch, advertisement, drawing, permit29 application, zoning request, computer design, etc.) or physical demarcation (including30 boundary signs, lot stakes, surveyor markings, etc.) indicating construction activities31 may occur on a specific plot. A common plan for development or sale identifies a site32 where multiple separate and distinct construction activities (areas of disturbance) are33 occurring on contiguous areas. Such sites may have one operator or owner or several34 operators and owners. Construction activities may take place at different times on35 different schedules, in separate stages, and/or in separate phases, and/or in36

No additional detail provided

Tagged Passions:construction, sites, sale, development, zoning, advertising, Development, and hearing

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xiv
Tagged Passions:stormwater

combination with other construction activities. Each Developer, Operator, or Owner for1 each Site or Project determined to be a part of an LCP are subject to permitting2 requirements as defined by Chapter 27 in the City of Charleston Ordinance and the City3 of Charleston Stormwater Design Standards Manual.4

No additional detail provided

Tagged Passions:ordinance, construction, and stormwater

Level Spreader: structure that is designed to uniformly distribute concentrated stormwater5 runoff over a large area. Level spreaders come in many forms, depending on the peak6 rate of inflow, the duration of use, the type of pollutant, and the site conditions. All7 designs follow the same principle:8 1) Concentrated flow enters the spreader through a pipe, ditch, or swale.9 2) The flow is retarded, energy is dissipated.10 3) The flow is distributed throughout a long linear shallow trench or behind a low berm.11 4) Water then flows over the berm/ ditch, theoretically, uniformly along the entire length.12

No additional detail provided

Tagged Passions:utility, Utility, water, and energy

Low Impact Development (LID): a set of principles and design components used to manage13 stormwater runoff by mimicking natural conditions and limiting pollutant transport14 through source control.15

Maintenance: any action necessary to preserve stormwater system components, including16 conveyances, facilities, and BMPs in proper working condition, in order to serve the17 intended purposes and to prevent structural failure of such components.18 Maximum Extent Practicable (MEP): a technology-based control standard used in the19 municipal stormwater program against which SCDHEC Bureau of Water and permittees20 assess whether an adequate level of control has been proposed in the SWMP.21
Tagged Passions:utility, development, Utility, program, water, Technology, Development, technology, and stormwater

Municipal Separate Storm Sewer System (MS4): conveyances or system of conveyances22 (including roads with drainage systems, highways, rights-of-way, municipal streets,23 catch basins, curbs, gutters, ditches, man-made channels, storm drains, detention24 ponds, and other stormwater facilities) that receives, transports, stores, or treats25 stormwater runoff and that is:26 Owned or operated by the City of Charleston;27 Designed or used for collecting or conveying stormwater;28 Not a combined sewer system; and29 Not a part of a publicly owned treatment works (POTW).30

Tagged Passions:sewer, streets, utility, Utility, commercial, and stormwater

National Pollutant Discharge Elimination System (NPDES) Permit: NPDES permit for31 stormwater discharges issued by SCDHEC pursuant to the CWA and the federal32 stormwater discharge regulations (40 C.F.R. 122.26) that allows for restricting pollutant33 loads as necessary to meet water quality standards.34

Tagged Passions:regulation, utility, Utility, union, water, and stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xv Navigable Waters: According to the EPA, a water body qualifies as a navigable water of the1 United States if it meets any of the tests set forth in 33 C.F.R. Part 329 (e.g., the water2 body is (a) subject to the ebb and flow of the tide, and/or (b) the water body is presently3 used, or has been used in the past, or may be susceptible for use [with or without4 reasonable improvements] to transport interstate or foreign commerce.5 Non-erodible: a material (e.g., natural rock, riprap, concrete, plastic, etc.,) that will not6 experience surface wear due to natural forces of wind, water, ice, gravity, or a7 combination of those forces.8 Nonpoint Source Pollution: pollution contained in stormwater runoff from ill-defined, diffuse9 sources.10 Non-stormwater Discharge: any discharge to the stormwater system or Waters of the State11 that is not composed entirely of stormwater.12 Operator: the person who is operating the property, the operator s agent, or any other person13 who acts in the operator s behalf.14
Tagged Passions:utility, Utility, transportation, water, property, and stormwater

Outlet Facility: stormwater management facility designed to regulate the elevation, rate, and15 volume of stormwater discharge from detention facilities.16

Owner: the legal property owner, the owner's agent, or any other person who acts in the17 owner's behalf.18
Tagged Passions:legal, facility, property, detention, and stormwater

Oxygen Demand: the amount of oxygen needed by aerobic organisms to break down organic19 material present in water.20

Tagged Passions:utility, Utility, and water

Person: any and all persons, natural or artificial and includes any individual, association, firm,21 corporation, limited liability company, business trust, estate, trust, partnership, two or22 more persons having a joint or common interest, or an agent or employee thereof, or23 any other legal entity.24

No additional detail provided

Tagged Passions:business and legal

Person Responsible for Land Disturbing Activity:25 Person who has or represents having financial or operational control over the land disturbing26

activity; and/or27 Landowner or person in possession or control of the land who directly or indirectly allowed28 the land disturbing activity or has benefited from it or who has failed to comply with any29 provision of this ordinance.30

Tagged Passions:ordinance and finance

pH: a quantitative measure of the acidity or basicity of aqueous or other liquid solutions. The31 scale ranges from 0 to 14 where low pH indicates the solution is acidic, high pH indicates32 the solution is basic/alkaline, and a pH of 7 indicates the solution is neutral.33

Pollutant: anything that may cause or contribute to exceedances of water quality standards,34 including but not limited to sediment, bacteria, nutrients, dredged spoil, solid waste,35

No additional detail provided

Tagged Passions:utility, solid waste, Utility, and water

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xvi
Tagged Passions:stormwater

incinerator residue, filter backwash, sewage, garbage, sewage sludge, munitions,1 chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded2 equipment, rock, sand, soil, and industrial, municipal, and agricultural waste discharged3 into receiving waters.4

Pollutant Load: a numeric value representing an estimate of the mass of a given pollutant5 entering a stormwater system or receiving water.6 Post-Development: the conditions that exist following the completion of the land disturbing7 activity in terms of topography, vegetation, land use and rate, volume, quality, and8 direction of stormwater runoff.9 Pre-Development: the conditions that existed prior to the initiation of the land disturbing10 activity, or at the time of Application, whichever is earlier, in terms of topography,11 vegetation, land use and rate, volume, quality, and direction of stormwater runoff.12 Qualified Individual: a licensed professional (as defined by the South Carolina Construction13 General Permit) who is authorized to prepare, amend, certify, and stamp a construction14 SWPPP. The Qualified Individual is knowledgeable in the principles and practices of15 erosion prevention and sediment controls and possesses the skills to assess16 conditions at the construction site that could impact stormwater quality and to assess17 the effectiveness of any EPSC measures selected to control the quality of stormwater18 discharges from the construction activity.19

Tagged Passions:construction, equipment, agriculture, utility, development, industrial, Utility, materials, water, Development, license, and stormwater

Project: improvements and structures proposed by the applicant to be built on a defined site20 as part of a common plan of construction, development, or re-development.21

No additional detail provided

Tagged Passions:construction, development, and Development

Public Infrastructure: Infrastructure that is owned by the public, represented by the22 government, for public use. Includes public water, sewer and stormwater facilities,23 electric lines, gas lines, telephone or cable television lines, curbs, and sidewalks located24 within the public right-of-way, and other public improvements.25

No additional detail provided

Tagged Passions:sewer, streets, utility, Utility, water, electric, Pedestrian, and stormwater

Rate: volume of water passing a point per unit of time, generally expressed in cubic feet per26 second (cfs).27

No additional detail provided

Tagged Passions:utility, Utility, and water

Receiving Water(s) or Waters of the State: refers to any lakes, bays, sounds, ponds,28 impounding reservoirs, springs, wells, rivers, streams, creeks, estuaries, marshes, inlets,29 canals, the Atlantic Ocean within the territorial limits of the State of South Carolina, and30 all other bodies of surface or underground water, natural or artificial, public or private,31 inland or coastal, fresh or salt.32

Tagged Passions:utility, Utility, water, and watershed

Redevelopment: development on a previously developed site where the impervious surface33 on the developed site is equal to or greater than 20 percent of the total site and where34 any repair, reconstruction, or improvement to an existing site and/or to any structures35 located on that site such that the cumulative costs of repairs, over a five-year period36

Tagged Passions:development and Development

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xvii equals or exceeds 50 percent of the fair market value of the property and the structures1 located on that property; but excludes ordinary maintenance activities, remodeling of2 existing building interiors, resurfacing of paved areas, and exterior building changes or3 improvements that do not materially increase or concentrate stormwater runoff, or4 cause additional nonpoint source pollution.5 Regulation: any regulation, rule, or requirement prepared by and/or adopted by the City of6 Charleston, the state, and federal regulatory agency(ies).7 Retention: the collection and storage of stormwater runoff without subsequent discharge to8 surface waters.9 Retention Structure: a permanent structure whose primary purpose is to permanently store a10 given volume of stormwater runoff. Release of the given volume is by infiltration, reuse,11 and/or evaporation.12 Retrofit: the process of altering an existing drainage system to function properly or more13 efficiently than currently exists.14
Tagged Passions:regulation, market, streets, utility, Utility, water, property, commercial, and stormwater

Sediment: solid particulate matter, both mineral and organic, that has been or is being15 transported by water, air, ice, or gravity from its site of origin.16

Tagged Passions:utility, Utility, and water

Sediment Control: the control of solid material, both mineral and organic, during a land17 disturbing activity to prevent its transport out of the disturbed area by means of air,18 water, gravity, or ice.19

Sedimentation: the process that operates at or near the surface of the ground, which deposits20 soils, debris, and other materials either on other ground surfaces or in the waterbody.21 Sedimentation Facility: any structure or area which is designed to retain suspended22 sediments from collected stormwater runoff, including sediment basins, and allows the23 sediment to settle out of the stormwater.24
Tagged Passions:facility, utility, Utility, materials, water, and stormwater

SEDPRO: Computer software program for modeling the hydrology and erosivity of a land25 development site and the sediment transfer and trapping efficiency of specific26 management practices.27

Tagged Passions:development, program, Development, government efficiency, information technology, and Information Technology

Sensitive Waters: any waters with approved or established TMDLs; any waters included in the28 most recent SCDHEC Bureau of Water CWA Section 303(d) list; and/or any waters29 pursuant to South Carolina s Classification Standards (R.61-68) and Classified Waters30 (R.61-69) regulations that are classified as either Outstanding National Resource31 Waters, Outstanding Resource Waters, Trout Waters, or Shellfish Harvesting Waters;32 and/or in Source Water Protection Areas.33

Single-Family Residence-Separately Built: a noncommercial dwelling that is occupied34 exclusively by one family and not part of a residential and subdivision development.35
Tagged Passions:regulation, utility, development, Utility, union, subdivision, water, and Development

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xviii Site: the land or water area where any development is physically located or conducted1 including adjacent land used in connection with the development, and borrow and spoil2 locations associated with the development.3 Small Municipal Separate Storm Sewer (SMS4 or as referenced herein MS4): Defined in4 South Carolina Water Pollution Control Permits Regulation 61-9, section 122.26(b)(16)5 and refers to all small separate storm sewer systems that are owned or operated by the6 United States, a state, city, town, borough, county, parish, district, association, or other7 public body (created by or pursuant to state law) having jurisdiction over disposal of8 sewage, industrial wastes, stormwater, or other wastes, including special districts under9 state law such as a sewer district, flood control district or drainage district, or similar10 entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and11 approved management agency under section 208 of the CWA that discharges to waters12 of the United States, but is not defined as large ' or medium municipal separate storm13 sewer system. This term includes systems similar to separate storm sewer systems in14 municipalities, such as systems at military bases, large hospital or prison complexes,15 and highways and other thoroughfares. The term does not include separate storm16 sewers in very discrete areas, such as individual buildings.17 Special Stormwater Management Area: areas within the City of Charleston that require some18 additional stormwater management controls due to existing concerns.19 Stabilization: the installation of vegetative or structural measures to establish a soil cover to20 reduce soil erosion by stormwater runoff, wind, ice, and gravity.21
Tagged Passions:regulation, sewer, hospital, utility, development, industrial, Utility, union, water, healthcare, flooding, Development, military, jail, and stormwater

Storm Frequency: the probability of recurrence of a storm event.22 Two-Year Frequency Storm: a storm that is capable of producing rainfall expected to be23

Tagged Passions:events

equaled or exceeded on the average of once in two years. It may also be expressed as an24 exceedance probability with a 50 percent chance of being equaled or exceeded in any given25 year.26 Five-Year Frequency Storm: a storm that is capable of producing rainfall expected to be27

equaled or exceeded on the average of once in five years. It may also be expressed as an28 exceedance probability with a 20 percent chance of being equaled or exceeded in any given29 year.30 Ten-Year Frequency Storm: a storm that is capable of producing rainfall expected to be31

equaled or exceeded on the average of once in 10 years. It may also be expressed as an32 exceedance probability with a 10 percent chance of being equaled or exceeded in any given33 year.34 Twenty-Five-Year Frequency Storm: a storm that is capable of producing rainfall expected35

to be equaled or exceeded on the average of once in twenty-five (25) years. It may also be36 expressed as an exceedance probability with a four (4) percent chance of being equaled or37 exceeded in any given year.38

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xix
Tagged Passions:stormwater

Fifty-Year Frequency Storm: a storm that is capable of producing rainfall expected to be1 equaled or exceeded on the average once in 50 years. It may also be expressed as an2 exceedance probability with a 2 percent chance of being equaled or exceeded in any given3 year.4 One Hundred Year Frequency Storm: a storm that is capable of producing rainfall expected5

to be equaled or exceeded on the average of once in 100 years. It may also be expressed as6 an exceedance probability with a 1 percent chance of being equaled or exceeded in any7 given year.8 Storm Surge: rising sea levels as a result of atmospheric pressure changes and wind9 associated with a storm.10 Stormwater: runoff or excess water caused by precipitation.11 Stormwater Management:12
Tagged Passions:utility, Utility, water, and stormwater

Quantitative control, a system of vegetative or structural measures, or both, that ensure no13 increase in volume and rate of stormwater runoff caused by man-made changes to the land14 Qualitative control, a system of vegetative, structural, or other measures that reduce or15

Tagged Passions:stormwater

eliminate pollutants that might otherwise be carried by stormwater runoff.16 Stormwater Management and Sediment Control Plan: a set of drawings, other documents,17

and supporting calculations submitted as a prerequisite to obtaining a permit to18 undertake a land disturbing activity, which contains all the information and19 specifications required by the City of Charleston. This plan is considered to be a part of20 the SWPPP.21
Tagged Passions:stormwater

Stormwater Management Program (SWMP): the City of Charleston's Stormwater22 Management Program, which describes the components to be used by the City of23 Charleston to control stormwater discharges, address flooding, and meet water quality24 standards. SWMP may also refer to the City of Charleston s Stormwater Management25 Plan developed to implement the Stormwater Management Program.26

No additional detail provided

Tagged Passions:utility, Utility, program, water, flooding, and stormwater

Stormwater Management System(s) and Drainage Facility(ies): natural and man-made27 channels, swales, ditches, swamps, rivers, streams, creeks, branches, reservoirs,28 ponds, drainage ways, inlets, catch basins, pipes, head walls, storm sewers, lakes and29 other physical works, properties, and improvements which transfer, control, convey, or30 otherwise influence the movement of stormwater runoff, be it for quantity or quality31 control.32

Tagged Passions:facility, sewer, utility, Utility, watershed, and stormwater

Stormwater Pollution Prevention Plan (SWPPP): a site-specific written document that33 Identifies potential sources of stormwater pollution;34 Describes stormwater control measures to reduce or eliminate pollutants in stormwater35

discharges; and36

Tagged Passions:stormwater

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xx
Tagged Passions:stormwater

Identifies procedures the operator will implement to comply with the terms and conditions1 of a permit.2

The SWPPP includes site map(s), drawings and plans, other documents, and supporting3 calculations, and identification of activities that could cause pollutants in the4 stormwater, and a description of measures or practices to control these pollutants. A5 SWPPP may be prepared for construction sites, municipal facilities, or industrial6 facilities.7 Stormwater Runoff or Runoff: the direct response of a watershed to precipitation and includes8 the surface and subsurface runoff that enters a ditch, stream, storm sewer or other9 concentrated flow during and following the precipitation. The part of rainfall that is not10 absorbed into the site but flows over the site as surface waters.11
Tagged Passions:construction, sewer, sites, utility, Utility, procedure, water, watershed, and stormwater

Structure: anything constructed or erected, the use of which requires a location on the ground,12 or attached to something having a location on the ground, including, but not limited to,13 tennis courts, swimming pools, fences, and buildings.14

No additional detail provided

Tagged Passions:legal and court

Subdivision: The division of a tract of land or of a parcel of land into two or more lots, building15 sites, or other divisions, for the purpose, whether immediate or future, of sale, legacy, or16 building developments, which includes any of the following:17 Creation of a new City road or the alteration of an existing road18 Need for drainage, sedimentation, or flood control measures,19 Installation of a water delivery system, or20 Installation of a sanitary sewerage system.21 Subdivision shall not include the division of a tract of land wherein each lot created22 meets the standards of the City of Charleston Department of Public Service regarding23 the use of individual wells and septic tanks and does not involve any of the activities24 referenced in items (1) through (4) above. When appropriate to the context, the term25 subdivision relates to the process of subdividing or to the land area subdivided.26

Tagged Passions:sites, streets, sale, utility, development, Utility, subdivision, water, flooding, Development, property, and stormwater

Subsurface: relating to or situated in an area beneath a surface or body of water.27 Swale: a vegetated open channel for the purposes of conveying stormwater with side slopes28

no steeper than 3H:1V. The cross-sectional shape may be triangular or trapezoidal.29 Tailwater: the water depth downstream of a hydraulic structure that restricts the flow of water30 from the structure.31 Total Maximum Daily Load (TMDL): a calculation of the maximum amount of a specific32 pollutant that a waterbody can receive and still meet water quality standards. It is the33 sum of the allowable loads or allocations of a given pollutant from all contributing point34 and nonpoint sources. It also incorporates a margin of safety and consideration of35

Tagged Passions:utility, Utility, water, and stormwater

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May 2019 xxi
Tagged Passions:stormwater

seasonal variation. For impaired waters, the TMDL document specifies the level of1 pollutant reductions needed for waterbody use attainment.2

Undeveloped Land: property not altered from its natural state by construction or installation3 of improvements such as roads, drainage improvements, buildings, structures, or other4 impervious surfaces, or which has less than 20 percent of its property covered by5 impervious surfaces.6 Variance: the modification of the minimum stormwater management requirements contained7 in Chapter 27 of the City of Charleston s Stormwater and Flood Ordinance and the8 SWMP for specific circumstances where strict adherence to the requirements would9 result in unnecessary hardship and not fulfill the intent of Chapter 27 of the City of10 Charleston s Stormwater and Flood Ordinance.11 Violator: a person who violates any provision of Chapter 27 of the City of Charleston s12 Stormwater and Flood Control Ordinance, the SWMP, the Stormwater Design Standards13 Manual, or any permit or authorization issued by the City of Charleston pursuant to the14 ordinance, SWMP, or SWDSM.15 Vegetation: all plant growth, especially trees, shrubs, mosses, and grasses.16 Waiver: the relinquishment from certain EPSC and stormwater management requirements by17 the Appropriate Plan Approval Authority for a specific land disturbing activity on a case-18 by-case review basis.19 Water Quality: characteristics of stormwater runoff or receiving waters that relate to the20 physical, chemical, biological, or radiological integrity of water.21 Water Quantity: characteristics of stormwater runoff that relate to the rate, duration, and22 volume of the stormwater runoff including characteristics of receiving waters.23

Tagged Passions:ordinance, construction, streets, utility, Utility, water, flooding, plant, trees, property, growth, and stormwater

Watercourse: any natural or man-made conveyance used to transport runoff from one location24 to the next.25

Waters of South Carolina, or Waters of the State: defined as lakes, bays, sounds, ponds,26 impounding reservoirs, springs, wells, rivers, streams, creeks, estuaries, marshes, inlets,27 canals, the Atlantic Ocean within the territorial limits of the State, and all other bodies of28 surface or underground water, natural or artificial, public or private, inland or coastal,29 fresh or salt, which are wholly or partially within or bordering the State or within its30 jurisdiction and all waters of the United States within the political boundaries of the State31 of South Carolina. Waste treatment systems, including treatment ponds or lagoons32 designed to meet the requirements of CWA, are not waters of South Carolina. This33 exclusion applies only to man-made bodies of water that neither were originally created34

Tagged Passions:utility, Utility, union, water, and watershed

City of Charleston Stormwater Design Standards Manual Upfront Sections

May 2019 xxii in waters of South Carolina (such as disposal areas in wetlands) nor resulted from the1 impoundment of waters of South Carolina.2
Tagged Passions:utility, Utility, water, and stormwater

Waters of the United States, or Waters of the U.S. (WOTUS):3 All waters that are currently used, were used in the past, or may be susceptible to use in4

interstate or foreign commerce, including all waters that are subject to the ebb and flow of5 the tide;6 All interstate waters, including interstate wetlands ;7 All other waters such as interstate lakes, rivers, streams (including intermittent streams),8 mudflats, sandflats, wetlands, sloughs, wet meadows, or natural ponds the use, degradation,9 or destruction of which would affect or could affect interstate or foreign commerce including10 any such waters:11 o That are or could be used by interstate or foreign travelers for recreational or other12
Tagged Passions:utility, Utility, transportation, water, watershed, and recreation

purposes;13 o From which fish or shellfish are or could be taken and sold in interstate or foreign14

commerce; or15 o That are used or could be used for industrial purposes by industries in interstate16
Tagged Passions:industrial and transportation

commerce;17 All impoundments of waters otherwise defined as waters of South Carolina under this18

No additional detail provided

Tagged Passions:utility, Utility, and water

definition;19 Tributaries of waters identified in paragraphs (a) through (d) of this definition;20 The territorial sea; and21 Wetlands adjacent to waters (other than waters that are themselves wetlands) identified in22

No additional detail provided

Tagged Passions:utility, Utility, and water

paragraphs (a) through (f) of this definition.23 Watershed: the drainage area contributing stormwater runoff to a single point.24 Wetlands: Those areas that are inundated or saturated by surface or groundwater at a25

frequency and duration sufficient to support, and that under normal circumstances do26 support, a prevalence of vegetation typically adapted for life in saturated soil conditions.27 Wetlands generally include swamps, marshes, bogs, and similar areas. Wetland areas28 typically fall under the jurisdiction of one or more of the following agencies: OCRM or29 the United States Army Corps of Engineers (USACE).30
Tagged Passions:watershed, military, and stormwater

31
City of Charleston Stormwater Design Standards Manual Upfront Sections

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Tagged Passions:stormwater

Executive Summary1 The objective of the City of Charleston Stormwater Design Standards Manual is to provide2 guidance on the design process during all phases of construction and the latest and best3 permanent construction stormwater management practices available to minimize the negative4 impacts of increasing stormwater runoff and its associated pollutants. Building on the previous5 version, this updated manual will help the City of Charleston take a comprehensive approach6 to stormwater management that integrates drainage design, stormwater quantity, and water7 quality considerations. The goal is to provide an effective tool for the City of Charleston and the8 development community to reduce both stormwater quality and quantity impacts and protect9 downstream areas and receiving waters.10 Stormwater management has entered a new era, and the City of Charleston recognizes the11 need for more innovative policies and practices. The requirements for NPDES municipal and12 industrial permits, TMDLs, and watershed assessments and the desire to protect human life,13 property, aquatic habitats, and the quality of life in the City of Charleston, have brought home14 the pressing need to manage both stormwater quality and quantity from developed and15 developing areas.16 To enhance its utility and ease of use, this manual has been divided into eight chapters. Each17 section provides information that supports the implementation of an integrated, green18 infrastructure-based approach to natural resource protection, stormwater management, and19 site design that can be used to protect the City of Charleston s and coastal South Carolina s20 valuable natural resources from the negative impacts of land development and nonpoint21 source pollution. The eight chapters presented in the document include:22

Chapter 1 Introduction and Legal Authority: Chapter 1 provides an introduction to the23 Stormwater Design Standards Manual and summarizes the legal authority the City of24 Charleston has been authorized to review and approve stormwater construction permits25 through federal, state, and local laws, regulations, and ordinances.26 Chapter 2 Conceptual Overview: Chapter 2 provides a conceptual overview of27 stormwater concepts, water quality and quantity, management and planning, LID design,28 various types of development, BMPs, and sea level rise.29 Chapter 3 Design Requirements: Chapter 3 provides information necessary to develop30 adequate systems that will control the rate, volume, and pollutants released from31 construction, development, and re-development projects. Chapter 3 also includes32 requirements for Special Stormwater Management Areas, sea level rise, landscape design,33 and additional design considerations.34 Chapter 4 Development Permitting: Chapter 4 provides information on the permitting35
Tagged Passions:planning, regulation, ordinance, recognition, construction, legal, utility, development, industrial, Utility, water, watershed, Development, property, buildings and grounds, and stormwater

process prior to any land disturbing activity. The chapter includes roles and responsibilities,36 types of projects and permits, approvals of applications, and any changes made after project37 approval, fees, and exemptions and exceptions.38

No additional detail provided

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Tagged Passions:stormwater

Chapter 5 Construction Phase: Chapter 5 provides requirements during the land1 disturbing phase of the construction process. The chapter includes implementation of2 temporary BMPs, requirements for changes to approved designs and approved stormwater3 pollution prevention plans, inspections by the construction applicant, owner, and/or4 operator during construction, and erosion prevention and sediment controls.5 Chapter 6 Post-Construction: Chapter 6 provides requirements for closeout operations6

during the post-construction phase. The chapter includes information on final stabilization7 of the site, inspections, and in situ testing by the construction applicant, owner, and/or8 operator, stormwater record drawings, city roadways inventory, final plats, stormwater GIS,9 maintenance plans and covenants, and stormwater facility warranties.10 Chapter 7 Inspections and Enforcement: Chapter 7 provides requirements for11 inspections and enforcement actions conducted by the City of Charleston. The inspection12 section of Chapter 7 includes duties and responsibilities for the City of Charleston, inspector13 qualifications, associated fees, and inspection reports. The enforcement section of Chapter14 7 includes information about common violations, correction orders, notices of violations,15 stop work orders, penalties, and uniform ordinance summons.16 Chapter 8 - References: Chapter 8 provides a singular location for all references in this17 manual. It includes references to laws, regulations, standards, ordinances, manuals, permits,18 studies, and websites.19 This manual is intended to provide guidance for the City of Charleston s government officials20 and staff on implementing stormwater management programs. Developers planning land21 disturbance activities in the City of Charleston will use this manual for the minimum22 requirements needed throughout the design process from the beginning of the project to23 closeout.24 Other interested parties and the general public may also find this manual helpful because it25 describes how managing stormwater improves water quality and quantity, helps protect the26 City of Charleston s valuable natural resources, and contributes to other social and economic27 benefits. Adoption of new comprehensive management strategies using LID concepts, such as28 green infrastructure, will reduce the negative impacts of stormwater runoff. These LID29 concepts help reduce runoff from new and re-development sites by using BMPs that30 encourage infiltration, evaporation, harvest, and use of stormwater runoff onsite.31
Tagged Passions:planning, regulation, ordinance, construction, facility, sites, GIS, utility, development, Utility, public safety, zoning, program, water, Development, and stormwater

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 1
Tagged Passions:stormwater

City of Charleston Signature Page ............................................................................................................ i

Contacts ............................................................................................................................................................ ii Record of Revisions......................................................................................................................................iii Acknowledgements ..................................................................................................................................... iv

Table of Contents ...........................................................................................................................................v

Acronyms and Abbreviations ................................................................................................................... vi Definitions........................................................................................................................................................ix Executive Summary ................................................................................................................................. xxiii Chapter 1. Introduction and Legal Authority ................................................................................... 1-1 1.1 Purpose ....................................................................................................................................................... 1-1 1.2 Scope ........................................................................................................................................................... 1-1 1.3 Legal Authority......................................................................................................................................... 1-1 1.4 Authorization ............................................................................................................................................ 1-2 1.5 Stormwater Related Laws, Regulations, and Permits ............................................................. 1-2
Tagged Passions:regulation, legal, and stormwater

1.5.1 Federal Clean Water Laws .................................................................................................... 1-3 1.5.2 Required Federal Permits ...................................................................................................... 1-4 1.5.3 South Carolina Water Laws .................................................................................................. 1-4 1.5.4 South Carolina Stormwater Related Regulations ....................................................... 1-5 1.5.5 Required South Carolina Permits ....................................................................................... 1-6

1.6 Section 303(d) Listed Waters and TMDLs ................................................................................... 1-7 1.7 City of Charleston Ordinances, Regulations, and Standards .............................................. 1-7
Tagged Passions:regulation, ordinance, utility, Utility, water, and stormwater

1.7.1 Qualifying Local Program ...................................................................................................... 1-7 1.7.2 1984 Master Drainage Plan .................................................................................................. 1-8 1.7.3 Level of Service for Maintenance ...................................................................................... 1-8

1.8 Easements ................................................................................................................................................. 1-8 1.9 Standards Superseded ........................................................................................................................ 1-9 1.10 Other Standards Sought ..................................................................................................................... 1-9 1.11 Duty to Comply ........................................................................................................................................ 1-9
Tagged Passions:program, easement, and stormwater

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 2 1.12 Engineering Design Accountability................................................................................................. 1-9 1.13 Severability ............................................................................................................................................. 1-10 1.14 Language and Interpretation of Text .......................................................................................... 1-10 1.15 Disclaimer ............................................................................................................................................... 1-11
Tagged Passions:accountability and stormwater

Chapter 2. Conceptual Overview ......................................................................................................... 2-1 2.1 Introduction ............................................................................................................................................... 2-1 2.2 Stormwater and Watersheds ............................................................................................................ 2-1

No additional detail provided

Tagged Passions:watershed and stormwater

2.2.1 Introduction to Stormwater .................................................................................................. 2-1 2.2.2 What is a Watershed? ............................................................................................................. 2-3 2.2.3 Changes from Natural Conditions to Development .................................................. 2-4 2.2.4 Effects of Development ......................................................................................................... 2-5

2.3 Introduction to Soils .............................................................................................................................. 2-6 2.4 Water Quality ............................................................................................................................................ 2-8 2.4.1 Suspended Solids.................................................................................................................. 2-10 2.4.2 Oxygen Demanding Matter and Bacteria .................................................................... 2-10 2.4.3 Nutrients .................................................................................................................................... 2-10 2.4.4 Illicit Discharge Detection and Elimination ................................................................. 2-11 2.5 Water Quantity ...................................................................................................................................... 2-12 2.5.1 Coastal and Tidal Flooding ................................................................................................ 2-13 2.5.2 Extreme Event (Flash) Flooding ....................................................................................... 2-14 2.5.3 Fluvial (Riverine) Flooding ................................................................................................... 2-14 2.5.4 Groundwater Flooding ......................................................................................................... 2-15 2.5.5 Surface Flooding .................................................................................................................... 2-16

Tagged Passions:utility, development, Utility, events, water, watershed, flooding, Development, and stormwater

2.6 Principles of Floodplain Management ........................................................................................ 2-17 2.7 Master Planning for Stormwater ................................................................................................... 2-18 2.8 Principles of Stormwater Management ..................................................................................... 2-18

No additional detail provided

Tagged Passions:planning and stormwater

2.8.1 Introduction to Stormwater Management .................................................................. 2-19 2.8.2 Innovative Design .................................................................................................................. 2-19 2.8.3 Site Planning ............................................................................................................................ 2-19

No additional detail provided

Tagged Passions:planning and stormwater

2.9 Types of Development ...................................................................................................................... 2-22 2.9.1 New Development ................................................................................................................. 2-22

No additional detail provided

Tagged Passions:development and Development

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 3 2.9.2 Redevelopment ...................................................................................................................... 2-22 2.9.3 Brownfields ............................................................................................................................... 2-23
Tagged Passions:environment and stormwater

2.10 Introduction to Permanent Best Management Practices .................................................. 2-23 2.11 Sea Level Rise ....................................................................................................................................... 2-24

No additional detail provided

Chapter 3. Design Requirements ......................................................................................................... 3-1 3.1 Introduction .................................................................................................................................................. 3-6 3.2 Determination of Construction Activity ........................................................................................... 3-6 3.3 Design Approach ....................................................................................................................................... 3-6 3.4 Stormwater Hydrology and Routing .................................................................................................. 3-8

No additional detail provided

Tagged Passions:construction and stormwater

3.4.1 Introduction to Hydrologic Requirements ........................................................................... 3-8 3.4.2 Rainfall and Design Storms ........................................................................................................ 3-9 3.4.3 Recommended Methods and Design Procedures ........................................................ 3-10 3.4.4 Collection and Conveyance Requirements ...................................................................... 3-12 3.4.5 Roadway Drainage Design ....................................................................................................... 3-19 3.4.6 Green Infrastructure ................................................................................................................... 3-22

No additional detail provided

Tagged Passions:procedure and stormwater

3.5 Special Stormwater Management Areas ...................................................................................... 3-22 3.5.1 Areas Associated With Flooding ........................................................................................... 3-23 3.5.2 Areas Discharging to TMDLs and Impaired Waters ..................................................... 3-24 3.5.3 Church Creek Drainage Basin Requirements .................................................................. 3-26

Tagged Passions:utility, Utility, water, church, flooding, and stormwater

3.6 Sea Level Rise .......................................................................................................................................... 3-27 3.7 Soils and Geotechnical Information - Germantown ................................................................. 3-27 3.8 Permanent Stormwater Design ........................................................................................................ 3-28

Tagged Passions:stormwater

3.8.1 Introduction to Permanent Stormwater Design Requirements ............................... 3-28 3.8.2 Design Volumes ........................................................................................................................... 3-29 3.8.3 Recommended Methods and Design Procedures ........................................................ 3-30

3.9 Detention, Retention, and Infiltration Requirements ............................................................... 3-34 3.9.1 Detention and Retention Requirements ............................................................................ 3-34 3.9.2 Detention Specific Requirements ........................................................................................ 3-35 3.9.3 Retention Specific Requirements ......................................................................................... 3-35 3.9.4 Infiltration Requirements .......................................................................................................... 3-36 3.10 Equalization Pipes and Submerged Systems .......................................................................... 3-37

Tagged Passions:procedure, detention, and stormwater

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 4 3.11 Accepted Permanent Structural and Non-Structural BMPs .............................................. 3-38 3.11.1 Stormwater Quantity BMPs .................................................................................................. 3-44 3.11.2 Stormwater Quality BMPs ..................................................................................................... 3-50
Tagged Passions:stormwater

3.12 Site Grading Requirements .............................................................................................................. 3-51 3.13 Erosion Prevention and Sediment Control................................................................................ 3-52

Tagged Passions:grading

3.13.1 Introduction to EPSC Requirements................................................................................. 3-52 3.13.2 Rainfall, Design Storms, and Design Volumes .............................................................. 3-52 3.13.3 Recommended Methods and Design Procedures ..................................................... 3-53 3.13.4 Accepted EPSC BMPs ............................................................................................................ 3-53 3.13.5 EPSC BMP Design Requirements ...................................................................................... 3-57

3.14 Landscape Design ............................................................................................................................... 3-60 3.14.1 BMP Soils and Compaction .................................................................................................. 3-61 3.14.2 Plant Selection ........................................................................................................................... 3-61 3.14.3 Fertilizer, Pesticides, Irrigation, and Mulch .................................................................... 3-63 3.15 Maintenance Access and Easements ......................................................................................... 3-66 3.15.1 Stormwater Pipe ........................................................................................................................ 3-66 3.15.2 Open Conveyances ................................................................................................................. 3-66 3.15.3 Detention and Retention Ponds ......................................................................................... 3-67 3.15.4 Other Stormwater Facilities and BMPs ............................................................................ 3-67 3.15.5 Offsite Easements .................................................................................................................... 3-67

Tagged Passions:agriculture, procedure, plant, buildings and grounds, pesticide, selection, detention, easement, and stormwater

3.16 Additional Design Considerations ................................................................................................ 3-67 3.16.1 Safety ............................................................................................................................................. 3-68 3.16.2 Signage and Stenciling ........................................................................................................... 3-68

Tagged Passions:advertising and signage

Chapter 4. Development Permitting ................................................................................................... 4-1 4.1 Overview of Application/Approval Process ................................................................................ 4-2 4.2 Roles and Responsibilities .................................................................................................................. 4-2

4.2.1 City of Charleston Stormwater Management ............................................................... 4-2 4.2.2 Applicant, Owner/Operator (Permittee) .......................................................................... 4-2 4.2.3 Engineer-of-Record ................................................................................................................. 4-3
Tagged Passions:development, Development, and stormwater

4.3 Permanent Structural Stormwater Facility Ownership ........................................................... 4-3 4.3.1 Residential ................................................................................................................................... 4-3

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Tagged Passions:facility and stormwater

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 5 4.3.2 Non-Residential ......................................................................................................................... 4-3 4.3.3 Easements ................................................................................................................................... 4-4
Tagged Passions:easement and stormwater

4.4 Construction Activity Applications ................................................................................................. 4-4 4.4.1 Who Must Submit an Application ....................................................................................... 4-5

Tagged Passions:construction

4.5 Types of Applications ........................................................................................................................... 4-5 4.5.1 Single Family Residence Applications ............................................................................. 4-6 4.5.2 Small Construction Activity Applications (Type I) ....................................................... 4-6 4.5.3 Medium Construction Activity Applications (Type II) ................................................ 4-6 4.5.4 Large Construction Activity Applications (Type III) ................................................. 4-13 4.5.5 Linear/Utility Applications .................................................................................................. 4-15

4.6 Additional Permits and Approvals ................................................................................................ 4-15 4.6.1 South Carolina Department of Transportation Encroachment Permits ........ 4-16 4.6.2 US Army Corps of Engineers Permits ........................................................................... 4-16 4.6.3 SC DHEC OCRM Coastal Zone Consistency Certification................................... 4-16

Tagged Passions:construction, utility, Utility, transportation, military, and encroachment

4.7 Approval of Applications .................................................................................................................. 4-17 4.8 Changes After Project Approval ................................................................................................... 4-17

No additional detail provided

4.8.1 Changes to Approved Applications ............................................................................... 4-17 4.8.2 Transfer of Responsibility (Change of Owner) .......................................................... 4-17 4.8.3 Expiration of City Approval ................................................................................................ 4-18

4.9 Fees ........................................................................................................................................................... 4-18 4.9.1 Construction Activity Fee................................................................................................... 4-18 4.9.2 Major Modification ................................................................................................................. 4-19

Tagged Passions:construction

4.10 Exemptions and Design Exceptions ............................................................................................ 4-19

No additional detail provided

Chapter 5. Construction Phase............................................................................................................. 5-1 5.1 Roles and Responsibilities .................................................................................................................. 5-2

5.1.1 City of Charleston Stormwater Management ............................................................... 5-2 5.1.2 Applicant, Owner/Operator (Permittee) .......................................................................... 5-2 5.1.3 Inspector ...................................................................................................................................... 5-2
Tagged Passions:construction and stormwater

5.2 Pre-Construction Requirements...................................................................................................... 5-2 5.2.1 Pre-Construction Activities .................................................................................................. 5-3 5.2.2 Inspection Fees ......................................................................................................................... 5-3

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Tagged Passions:construction

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 6 5.2.3 Other Planning Considerations........................................................................................... 5-3 5.2.4 Pre-Construction Meeting .................................................................................................... 5-4 5.3 Construction Requirements............................................................................................................... 5-5 5.3.1 Implement and Maintain EPSC BMPs ............................................................................... 5-5 5.3.2 Conduct Inspections ............................................................................................................... 5-5 5.3.3 Maintain Stormwater Documents On-Site ..................................................................... 5-7 5.3.4 Spills and Illicit Discharge Detection and Elimination ............................................... 5-7 5.4 Changes During Construction .......................................................................................................... 5-7 5.4.1 Changes to Approved Design ............................................................................................. 5-8 5.4.2 Changes to Approved SWPPP ............................................................................................ 5-8 5.4.3 Qualifications .............................................................................................................................. 5-9 5.4.4 Transfer of Responsibility (Change of Owner) ............................................................. 5-9 5.4.5 Expiration of City Approval ................................................................................................ 5-10 5.4.6 Notifications ............................................................................................................................. 5-10 Chapter 6 - Post-Construction ............................................................................................................. 6-1 6.1. Overview of Project Closeout Requirements ............................................................................. 6-4 6.2. Final Stabilization and Project Closeout ....................................................................................... 6-4
Tagged Passions:planning, construction, and stormwater

6.2.1. Single-Family Residential (SFR) .......................................................................................... 6-4 6.2.2. Site Plan (Commercial, multi-family) Projects ............................................................... 6-4 6.2.3. Subdivision/Road Construction Plan Projects ............................................................. 6-5 6.2.4. Utility Projects ............................................................................................................................ 6-5

No additional detail provided

Tagged Passions:construction, streets, utility, Utility, subdivision, and commercial

6.3. Stormwater Record Drawings (As-Builts) ..................................................................................... 6-5 6.3.1. Piped Drainage Systems ....................................................................................................... 6-6 6.3.2. Open Channel Drainage Systems...................................................................................... 6-6 6.3.3. Stormwater Management Pond or Basin ....................................................................... 6-6 6.3.4. Project Datum ............................................................................................................................ 6-7 6.3.5. Certifications Statement ....................................................................................................... 6-7

6.4. Maintenance Plan and Covenants ................................................................................................... 6-7 6.5. Final Plat...................................................................................................................................................... 6-8 6.6. Stormwater Video Inspection ........................................................................................................... 6-8 6.7. Stormwater Facility Warranty ............................................................................................................ 6-9

Tagged Passions:facility, zoning, and stormwater

City of Charleston Stormwater Design Standards Manual Table of Contents

May 2019 Page 7 6.8. Hydrostatic Testing and Dye Testing ......................................................................................... 6-11 6.9. In-Situ Testing of BMPs .................................................................................................................... 6-12 6.10. City Roadways Inventory/Stormwater GIS ............................................................................... 6-16 Chapter 7. City Inspection and Enforcement ................................................................................... 7-1 7.1 Stormwater Management Inspections .......................................................................................... 7-1
Tagged Passions:GIS and stormwater

7.1.1 City Inspection Duties and Responsibilities .................................................................. 7-1 7.1.2 Inspector Qualifications ......................................................................................................... 7-2 7.1.3 Inspection Reports ................................................................................................................... 7-2

7.2 Enforcement ............................................................................................................................................. 7-2 7.2.1 Administrative Order ............................................................................................................... 7-3 7.2.2 Notice of Violation .................................................................................................................... 7-5 7.2.3 Uniform Ordinance Summons ............................................................................................. 7-6 7.2.4 Civil and Criminal Penalties................................................................................................... 7-6

Tagged Passions:ordinance

Chapter 8. References ............................................................................................................................. 8-1

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City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

CHAPTER 1. INTRODUCTION AND LEGAL AUTHORITY1 1.1 Purpose2 Stormwater management is extremely important, particularly in coastal cities, such as the City3 of Charleston (City). With sea level rise, king tides, and the increase in population density, the4 City has and will continue to implement high standards in regard to public infrastructure,5 development, and redevelopment projects. The purpose of the Stormwater Design Standards6 Manual (SWDSM) is to provide guidance on the design of the City s stormwater system. The7 SWDSM addresses issues related to pre-construction and permitting, construction, and post-8 construction for public infrastructure, development, and redevelopment projects within the9 City. The SWDSM describes the policies and procedures that shall be used by the City s10 Department of Stormwater Management to implement the City s ordinances related to11 stormwater. The SWDSM provides:12 Application submittal requirements and approval process.13 Technical design standards, to include standards that address flow rates, runoff volume,14 and pollutant load/concentration, as well as standards applicable during construction, and15 post construction performance.16 General information on measures to improve water quality, prevent illicit discharges, and17 minimize stormwater runoff impacts due to construction activity, development, and18 redevelopment.19 Other protection provisions related to stormwater discharges such as wetlands and20 watercourse conservation.21
Tagged Passions:ordinance, construction, legal, utility, development, Utility, procedure, performance, water, Conservation, Development, rates, and stormwater

1.2 Scope22 The SWDSM is intended to be a resource for City officials, staff, designers, and developers on23 the stormwater design requirements approved by the City s Department of Stormwater24 Management. Additionally, the SWDSM provides information to the interested citizen regarding25 the City s approach to stormwater management.26

Tagged Passions:stormwater

1.3 Legal Authority27 Federal regulatory agencies delegate authority to the states, providing that state requirements28 meet or exceed federal requirements. The United States Environmental Protection Agency29 (EPA) delegates authority for the Clean Water Act (CWA) and other environmental laws to the30 state of South Carolina. In turn, South Carolina Department of Health and Environmental31

Tagged Passions:health, regulation, legal, utility, Utility, union, water, and environment

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

Control (SCDHEC) is the regulating and permitting agency of the state. SCDHEC has the1 authority to delegate authority to local stormwater management programs, if said programs2 meet or exceed federal and state requirements. The City has combined federal, state, and local3 laws, regulations, and ordinances for stormwater into the SWDSM.4 The SWDSM incorporates design standards that are required by the regulatory agencies. The5 City requires any construction activity to incorporate the standards stated in the manual, or6 enforcement and correct actions will be taken. The strict adherence the City takes with the7 SWDSM and future construction activities will improve flood control, water quality, and8 infrastructure integrity.9
Tagged Passions:regulation, ordinance, construction, legal, utility, Utility, program, water, flooding, and stormwater

1.4 Authorization10 The SWDSM has been prepared under the direction of the Department of Stormwater11 Management, which has been granted the authority by the City Council to develop engineering12 design standards and enact programs and policies to ensure compliance with state and federal13 laws for the purposes previously described. A detailed description of the laws, regulations, and14 assigned authorizations to the City is provided below.15

No additional detail provided

Tagged Passions:grant, regulation, council, program, and compliance

1.5 Stormwater Related Laws, Regulations, and Permits16 Any construction activity is required by law to regulate water quality and quantity to protect the17 waters of the State and waters of the United States (WOTUS). Federal laws and regulations18 provide the overarching guidelines for the United States. South Carolina laws include Federal19 laws, and require other regulations specific to the state. This section contains the Federal and20 State laws, regulations, and permits that are included and required by the City s Stormwater21 Ordinance and are encompassed in the SWDSM (Figure 1).22

Tagged Passions:regulation, ordinance, construction, utility, Utility, water, and stormwater

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

Tagged Passions:legal and stormwater

1
Figure 1. The hierarchy of laws and regulations from Federal to Local Governments.2

Tagged Passions:regulation

1.5.1 Federal Clean Water Laws3 1.5.1.1 Clean Water Act4

The Federal Water Pollution Act, as amended by the Clean Water Act (CWA) requires the5 reduction of water pollution and gives EPA the congressional authority to develop programs to6 improve the health of navigable waters. EPA developed regulations that created a program of7 discharge permits as part of the National Pollutant Discharge Elimination System (NPDES) to8 regulate point sources from a variety of discharges. The 1987 amendments to the CWA9 extended NPDES permits to industrial discharges, including stormwater runoff associated with10 land disturbing activity. The 1987 CWA Amendments also require NPDES permitting for11 stormwater runoff from urbanized areas. A Municipal Separate Storm Sewer System (MS4)12 NPDES permit is required based on population. Authority to administer the NPDES permit13 program was delegated to state agencies, such as SCDHEC, by EPA.14
Tagged Passions:health, regulation, sewer, utility, industrial, Utility, union, program, water, and stormwater

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

Tagged Passions:legal and stormwater

1.5.1.2 Federal Coastal Zone Management Act of 19721 The United States Congress recognized the fragile balance between economic growth and2 preservation of the environment and passed the Coastal Zone Management Act (CZMA) in3 1972. The goal of CZMA is to preserve, protect, develop, and where possible, to restore or4 enhance the resources of the nation s coastal zone. CZMA is administered by the National5 Oceanic and Atmospheric Administration (NOAA) and provides for the management of the6 nation s coastal resources. Coordination between Federal and State jurisdictions is a7 requirement, and allows flexibility to local programs to address their specific needs.8

1.5.2 Required Federal Permits9 1.5.2.1 United States Army Corps of Engineers 404 Permit10 Under the CWA Section 404(b)(1) Guidelines, EPA established regulations and guidelines for11 discharges of dredged or fill materials into the WOTUS, including wetlands. The United States12 Army Corps of Engineers (USACE) are charged with evaluating applications of the 404 Permit13 under a public interest review, CWA, and additional regulations promulgated by EPA. The basis14 of the 404 Permit is to show that steps have been taken to avoid discharges of dredged or fill15 material into WOTUS, potential impacts have been minimized, and compensation will be16 provided for all remaining unavoidable impacts. Activities requiring a 404 Permit include but are17 not limited to fill for development, water resources projects (e.g., dams and levees),18 infrastructure development (e.g., highways and airports), and mining activities.19
Tagged Passions:compensation, regulation, recognition, airport, utility, development, Utility, union, materials, program, water, Conservation, environment, Development, preservation, military, and growth

1.5.3 South Carolina Water Laws20 1.5.3.1 South Carolina Pollution Control Act21

The South Carolina Pollution Control Act (PCA) was originally enacted in 1950 and was last22 amended in 1970 during the initial stages of the environmental movement. It was written very23 broadly and is applicable to essentially any activity that could negatively impact the24 environment by requiring attainment of a permit and implementation of measures to mitigate25 potential negative impacts.26
Tagged Passions:utility, Utility, water, Conservation, and environment

1.5.3.2 South Carolina Stormwater Management and Sediment Reduction27 Act28

The South Carolina Stormwater Management and Sediment Reduction Act of 1991 (SMSRA)29 S.C. Code Ann. 48-14-10 et seq. was enacted to address the increase in stormwater runoff30 rate and quantity, the decrease of rainwater infiltration, and the increase in erosion associated31

Tagged Passions:stormwater

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

with the extensive urban development occurring throughout the state. SMSRA gave legislative1 authority to SCDHEC to enact programs to meet its purpose.2
Tagged Passions:legal, development, program, Development, and stormwater

1.5.3.3 South Carolina Coastal Zone Management Act3 CZMA provides grants to states that develop and implement federally approved coastal zone4 management plans. The Office of Ocean and Coastal Resource Management (OCRM), a division5 of SCDHEC, implements this management plan for the state s eight coastal counties as6 established by the Coastal Zone Management Act of 1976. Within the coastal zone, the7 program provides authority to review any project requiring a state permit (certification), a8 federal permit or license (including NPDES), federal funding, as well as direct federal activities9 to determine whether the project is consistent with the policies and procedures of the South10 Carolina Coastal Zone Management Program.11

No additional detail provided

Tagged Passions:funding, grant, procedure, program, and license

1.5.4 South Carolina Stormwater Related Regulations12 South Carolina became the permitting authority over the NPDES Stormwater Program through13 SMSRA in 1991. SCDHEC has the responsibility of enforcing the stormwater regulations. These14 regulations provide information about stormwater standards and the regulatory process.15 Below is a list of regulations from SCDHEC:16

Reg. 61-9 Water Pollution Control Permits17 Reg. 61-68 Water Classifications and Standards18 Reg. 61-69 Classified Waters19 Reg. 61-110 Total Maximum Daily Loads (TMDLs) for Pollutants in Water20 Reg. 72-101 through 72-108 Erosion and Sediment Reduction and Stormwater21 Management22 Reg. 72-300 through 72-316 Standards for Stormwater Management and Sediment23 Reduction24 Reg. 70-405 through 72-445 Standards for Stormwater Management and Sediment25 Reduction26

Tagged Passions:regulation, utility, Utility, program, water, and stormwater

1.5.5 Required South Carolina Permits27 1.5.5.1 Ocean and Coastal Resource Management Coastal Zone Consistency28

Under the guidelines of CZMA and South Carolina Coastal Tidelands and Wetlands Act of 197729 (CTWA), the South Carolina Coastal Management Program was established to manage coastal30
Tagged Passions:program

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

Tagged Passions:legal and stormwater

resources. Under the program, a Coastal Zone Consistency (CZC) Certification is required for1 any land disturbing activities in the coastal counties, including Charleston County, prior to2 receiving coverage under the NPDES Permit Program. All CZC Certifications are granted3 through the OCRM in SCDHEC. CZC Certification guarantees a balance of environmental4 protection and economic and social improvements of the coastal zone. A CZC Certification5 must be obtained prior to applying for any Federal or State permit.6

Tagged Passions:program

1.5.5.2 NPDES General Permit for MS4s (Permit No. SCR030000)7 The City is required to have a NPDES permit to discharge stormwater from MS4, officially titled8 as the State of South Carolina NPDES General Permit for Storm Water Discharges from9 Regulated Small Municipal Separate Storm Sewer Systems (SMS4). Since land disturbing10 activities contribute to the discharge of pollutants, the NPDES permit requires that the City11 encourage, promote, and implement certain practices, programs, and procedures for the12 purpose of reducing or limiting discharge of pollutants into receiving waters of the State. The13 permit requires that the City develop and implement a Stormwater Management Program14 (SWMP) to control the discharge of pollutants from its MS4 to the maximum extent practicable15 (MEP).16

Tagged Passions:sewer, utility, Utility, procedure, program, water, and stormwater

1.5.5.3 NPDES Industrial General Permit (Permit No. SCR000000)17 All stormwater runoff from industrial activities is considered an illegal discharge without an18 NPDES discharge permit. The permit is titled NPDES General Permit for Storm Water19 Discharges Associated with Industrial Activities (Except Construction), and is informally known20 as the Industrial General Permit (IGP). These permits require certain industries to develop and21 implement a Stormwater Pollution Prevention Plan (SWPPP), which must include appropriate22 best management practices (BMPs) to minimize pollution to receiving waters. The two general23 types of industrial activity permits are construction related and other. Coverage under the24 NPDES General Permit for Stormwater Discharges from Construction Activities is required for25 all construction sites that disturb one-half ( ) or more acres of land. Coverage is required for26 all construction activities within mile of a receiving water. The requirements for obtaining and27 complying with this type of permit are the focus of the SWDSM.28

Tagged Passions:construction, sites, utility, industrial, Utility, water, and stormwater

1.5.5.4 NPDES Construction General Permit (Permit No. SCR100000)29 All stormwater runoff from construction activities is considered an illegal discharge without a30 NPDES discharge permit. The NPDES General Permit for Stormwater Discharges from31 Construction Activities, also known as a Construction General Permit (CGP), addresses32 discharges during and post construction activities. Requirements for discharges during33 construction activities set forth in the permit are based on the CWA, 33 U.S.C. 1251 et seq.34 and the PCA, S.C. Code Sections 48-1-10 et seq. Additional requirements are established35

Tagged Passions:construction, union, and stormwater

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

in South Carolina Regulation 61-9. Water Pollution Control Permits, South Carolina1 Regulation 72-300, SMSRA, and coastal zone citation. EPA has delegated the authority to2 implement the CGP to SCDHEC within the state of South Carolina.3 The Larger Common Plan (LCP) is any announcement, piece of documentation, or physical4 demarcation indicating construction activities may occur on a specific plot of land (63 Federal5 Register No. 128). Any land disturbing activities (e.g., clearing, grading, or excavating) are6 required to obtain coverage for stormwater discharges under the NPDES CGP. This7 requirement includes disturbed area of less than 1 acre.8 1.6 Section 303(d) Listed Waters and TMDLs9 Through the provision of Section 303(d) of the CWA, EPA requires the states to submit a list of10 all waterbodies (303(d) Listed Waters) that do not meet minimum water quality standards every11 two years. The 303(d) list allows water quality impairments to be identified and corrective12 actions to be implemented. Once on the Section 303(d) List, a TMDL for the waterbody must13 be developed within 2 to 13 years of the initial listing by the state. SCDHEC develops the TMDL14 and forwards the information to the EPA Region 4 office for final approval.15 1.7 City of Charleston Ordinances, Regulations, and Standards16 1.7.1 Qualifying Local Program17 EPA gives authority of NPDES permitting agencies SCDHEC to recognize when a local18 sediment and erosion control program meets or exceeds the requirements of the stormwater19 regulation 40 C.F.R. 122.44(s). SCDHEC has the authority to incorporate the local program by20 reference in its permit for construction activities. The local program is then known as a21 Qualifying Local Program (QLP). The advantages of a QLP include streamlining the permit22 process and providing one set of requirements for construction activities. QLPs allow23 municipalities to modify stormwater programs to meet local needs as long as the requirements24 are met on a state and federal level. QLPs undertake the responsibility of reviewing and25 approving erosion and sediment control plans, inspecting sites to ensure compliance, and26 taking corrective actions when needed to protect water quality.27 The City has promulgated and adopted ordinances and standards based on State and Federal28 regulations to address concerns associated with uncontrolled stormwater runoff. A number of29 ordinances and standards for the City may affect construction activities, and the development30 and redevelopment of land, such as:31
Tagged Passions:regulation, ordinance, recognition, construction, legal, sites, utility, Utility, union, program, water, compliance, grading, and stormwater

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

Building1 Design, Development, and2 Preservation3 Floodplain4
Tagged Passions:legal, development, Development, and stormwater

Stormwater Management5 Ordinances6 Utilities7 Zoning8

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Tagged Passions:stormwater

Other ordinances and standards may also be applicable and should be consulted as necessary.9

No additional detail provided

Tagged Passions:ordinance

1.7.2 1984 Master Drainage Plan10 The 1984 Master Drainage Plan was the first phase of a four-phase plan to improve the existing11 stormwater facilities in the City. The plan was submitted in compliance with the agreement12 between the City and the Engineers and constituted the completion of the first phase of13 identifying the existing drainage problems and recommendations for improvement. The Master14 Drainage Plan included all areas within the 1984 City boundaries.15

Tagged Passions:compliance and stormwater

1.7.3 Level of Service for Maintenance16 Level of Service (LOS) is a set of standards and services the community can expect from the17 stormwater management program. The citizens of the City are ensured consistent and18 reasonable standards of service through paying the monthly stormwater fee. The City will19 maintain the MS4 and certify the system is serviceable and has minimal negative impact on the20 receiving waters in order to comply with the requirements set forth by SCDHEC. The LOS and21 fee can only be applied within the City boundaries and MS4 jurisdiction.22

No additional detail provided

Tagged Passions:utility, Utility, services, program, water, and stormwater

1.8 Easements23 An easement is a right of use for access granted on, above, under, or across a tract of land by24 the landowner to another person or entity (Section 54-1051(k) Ord. No. 2018-031 11, 4-10-25 18). Specifically, a drainage easement is the right of access of stormwater runoff from adjacent26 drainage basins into the drainage way within the defined easement (Section 54-1051(i) Ord.27 No. 2018-031 11, 4-10-18). Easements are permanent and exist even after transfer of28 ownership of property. An example of an easement agreement with the City is located in29 Appendix A. The City uses easements for maintenance and repairs of stormwater30 infrastructure and other utilities within the easement.31

No additional detail provided

Tagged Passions:grant, utility, Utility, property, easement, and stormwater

1.9 Standards Superseded32 When the SCDHEC or the City updates design standards associated with stormwater33 discharges, the City must provide notification of the new design standards and the cancellation34

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City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

of current design standards via the City s website. The City must also provide a timeline when1 the new design standards will be implemented.2 1.10 Other Standards Sought3 The City shall require the most restrictive standard as the driver of design standards:4 Whenever the provisions of this article impose more restrictive standards than5 are required in or under any other law, regulation, or article, the requirements6 contained in this article shall prevail. Whenever the provisions of any other law,7 regulation, or ordinance require more restrictive standards than are required in8 this article, the requirements of such law, regulation, or ordinance shall prevail.9 (Ord. No. 2007-158, 2, 8-21-07) 10
Tagged Passions:regulation, ordinance, legal, and stormwater

1.11 Duty to Comply11 Unless otherwise allowed by the Stormwater Management Ordinance or the SWDSM, the12 surface of land in the City shall not be disturbed or altered for any purpose whatsoever, nor any13 major drainage channel or component of the stormwater system impeded or encroached upon14 without approval from the Department of Stormwater Management. Construction,15 development, and redevelopment activities cannot commence prior to approval from the16 Department of Stormwater Management and other City Departments as necessary.17

1.12 Engineering Design Accountability18 The SWDSM will assist engineers, plan reviewers, inspectors, and contractors in the design and19 layout of most land disturbance projects. The user of the SWDSM is hereby cautioned that20 many aspects of engineering design must be considered, including but not limited to:21

Tagged Passions:ordinance, construction, development, Development, and stormwater

Public health and safety22 Site-specific conditions or unusual features of a project site that warrant special designs23 Current versions of design texts, manuals, technical documents, and research24

The design engineer must have sufficient education and experience to perform a complete and25 thorough design of each element shown on the construction plans and must also have26 complete control to change or alter the plans during the design phase. The design engineer27 shall thoroughly investigate field conditions and coordinate all design efforts with the City.28 Construction plans, site plans, details, calculations, construction specifications, and other29 technical documents must be designed, stamped, and sealed by a Professional Engineer30

Tagged Passions:health, construction, public safety, education, and unusual

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

or Tier B Land Surveyor actively licensed in the state of South Carolina, unless otherwise1 stated in the SWDSM.2 The SWDSM is not intended to restrain or inhibit engineering creativity, freedom of design, or3 the need for engineering judgment. When shown to be applicable, it is encouraged that new4 procedures, techniques, and innovative stormwater BMPs be submitted with supporting5 documentation. However, the use of such approaches shall be substantiated with submitted6 documentation by design engineers showing that the proposed design is equal to or exceeds7 the traditional procedures in terms of performance and economic feasibility.8
Tagged Passions:legal, procedure, performance, license, and stormwater

1.13 Severability9 It is the declared intent of the City that if any portion of the SWDSM is ruled to be invalid or10 unconstitutional by any court with adequate jurisdiction over the City, then such portion shall11 be considered to have been selectively removed from the SWDSM without affecting the overall12 applicability, validity, or enforceability of any remaining provisions, and it is the intent of the City13 that such remaining provisions shall continue in full force and effect.14

Tagged Passions:legal and court

1.14 Language and Interpretation of Text15 The following language rules are applicable to the SWDSM:16

The imperative case is always mandatory. The words shall and must are always17 mandatory. These actions must be performed unless sufficient engineering justification is18 submitted to the City s Department of Stormwater Management and written approval has19 been specifically granted.20 The word should indicates an action that is highly recommended under most conditions.21 The word may indicates an allowable action or choice that is usually beneficial in meeting22 the minimum City requirements.23 Use of the singular or plural case of a noun shall not affect the applicability of the SWDSM,24
Tagged Passions:grant and stormwater

or any other law, regulation, or ordinance, unless the context of the sentence specifically25 indicates that the singular/plural case affects the intended use or function on a scientific or26 engineering basis. The use of a singular or plural noun does not necessarily indicate27 whether to design or construct a single unit or multiple units.28 Any reference to the Department of Stormwater Management shall mean the duly29

authorized representatives, sections, or employees under the Director s supervision who30 have delegated responsibilities. Areas of delegated responsibility may include, but are not31 limited to, review and approval of plans, review and approval of survey plats, interpretation32 of standards or requirements, approval of special conditions, review and issuance of33
Tagged Passions:regulation, ordinance, zoning, and stormwater

City of Charleston Stormwater Design Standards Manual Introduction and Legal Authority

Tagged Passions:legal and stormwater

approvals, inspections and field investigations, enforcement actions, issuing notices of1 violation, conducting public meetings, etc.2 The use of and shall imply conjunction of items in lists of required elements, in which all3

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items must be complied with.4 The use of or shall imply the disconnection of items in lists of required elements, in which5

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either or one or the other items in the list must be complied with.6 The rules of verbal construction found in the Stormwater Management Ordinance apply to7

the SWDSM.8

Tagged Passions:ordinance, construction, and stormwater

1.15 Disclaimer9 The SWDSM is not intended as a textbook or as a comprehensive engineering design10 reference. It was developed under the assumption that the user possesses a thorough11 understanding of stormwater control design, construction, and land development. Guidance12 documents from federal, state, and local agencies as well as other relevant references are13 given throughout the SWDSM and are only for the purposes of providing additional references14 and information. See Chapter 8 for a complete listing of recommended references.15

Tagged Passions:construction, development, Development, textbook, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

Tagged Passions:stormwater

CHAPTER 2. CONCEPTUAL OVERVIEW1 2.1 Introduction2 This chapter provides a conceptual overview of stormwater, the site conditions that dictate3 stormwater runoff quantity and quality, and the impacts that urban development have on4 stormwater. The topics introduced throughout this chapter are intended to establish a baseline5 understanding of stormwater concepts for developers, engineers, and any other members of6 the general public who have an interest in the many factors that impact stormwater7 management in the Charleston area. Later chapters will go more in depth into the stormwater8 considerations that factor into design, permitting, and construction.9

2.2 Stormwater and Watersheds10 The City is flush with water resources that we all enjoy. This chapter describes how proper11 stormwater management can protect and preserve these water resources for generations to12 come.13

Tagged Passions:construction, utility, development, Utility, water, Development, and stormwater

2.2.1 Introduction to Stormwater14 During a storm, rainfall can either be intercepted by plants and trees, or fall on the land. In a15 natural condition, the land is able to absorb the majority of rainfall by a process called16 infiltration. As the land is developed and becomes urbanized, more of the landscape is covered17 by impervious surfaces, such as rooftops, pavement, and compacted soil. As shown on Figure18 2-1, an increasing percentage of impervious surface results in less rainfall being infiltrated into19 the soil, and more of the rainfall running off. These hard surfaces generate a larger volume of20 stormwater runoff, and without the natural obstacles that would otherwise slow the water down,21 the runoff travels at a faster rate. Fast-moving, large volumes of water cause erosion and22 flooding, and can damage land and property downstream. Additionally, as the runoff travels23 over the land, it picks up pollutants. Pollutants are any substance or material not naturally24 present in rainwater or surface water, or a natural substance that is present in excessive25 quantities (such as sediment). Impaired waters cannot be used as intended, for recreation,26 water supply, fishing or shellfishing, etc., due to pollution, or may lose their ability to support27 aquatic life.28

No additional detail provided

Tagged Passions:travel, utility, Utility, water, flooding, plant, trees, property, buildings and grounds, recreation, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

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1
Figure 2-1: Diagram depicting changes in runoff and infiltration with increasing amounts of2 impervious surface (Source: City of Charleston Redevelopment Standards for Stormwater).3

The basis for stormwater design in the City is the storm annual exceedance probability (AEP)4 percentage, or the percent chance that a 24-hour rain event will occur in any given year, for the5 area. For example, a 1 probability storm event in Charleston will result in 10.3 inches of6 precipitation over a 24-hour period. The AEP is determined using historical rainfall and tide7 gage data within a given region. AEP will be used as opposed to recurrence intervals to avoid8 the public confusion that occurs in certain situations, such as when multiple 100 year storm9 events occur over a period of five years. Table 2-1 shows the equivalents for the most10 commonly used storm recurrence intervals and AEPs.11
Tagged Passions:historical, events, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

Table 2-1: Recurrence Interval Compared to Annual Exceedance Probability1 Recurrence Interval (years) Annual Exceedance Probability (percent)
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2
years 50 5 years 20

10
years 10 25 years 4 50 years 2

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100 years 1 2

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2.2.2 What is a Watershed?3 A watershed is an area of land that drains to a single point, bounded by higher elevations at the4 edges. Within a watershed, water travels over land until it reaches a body of water, and as the5 water passes farther downstream, draining a larger area, pollutants can accumulate. Ultimately,6 the rivers and streams reach the ocean, and any accumulated pollutants are discharged into7 the ocean. In coastal areas, wetlands fringe the edge of the land, and many of the local streams8 and creeks enter wetlands before discharging to the ocean. Wetlands perform a crucial9 function in the watershed, intercepting pollutants carried downstream and removing them from10 the water in a natural treatment process. Additionally, wetlands slow the water down, allowing11 some of the runoff to infiltrate or be stored in the wetlands and slowly released long after the12 storm has passed. Figure 2-2 depicts how wetlands work.13

Tagged Passions:travel, utility, Utility, water, watershed, and commercial

City of Charleston Stormwater Design Standards Manual Conceptual Overview

Tagged Passions:stormwater

1
Figure 2-2: Diagram depicting role of wetlands in a watershed (Source: City of Charleston2

Redevelopment Standards for Stormwater).3 2.2.3 Changes from Natural Conditions to Development4 Land development is the process of converting natural landscapes, such as forests, swamps,5 and grasslands, to developed, urban, or residential areas. This process typically begins with site6 clearing, which is the removal of trees, shrubs, and other vegetation. The landscape is then7 graded using a combination of cut and fill of the existing soil surface to provide clear, level8 building sites. In place of the previously vegetated land, developed, impervious areas such as9 buildings, roads, and parking lots are constructed. By altering the landscape from a natural to a10 developed condition, the hydrology of the site is also changed. The natural drainage pathways11 that dominate the undisturbed stormwater system are replaced with a system of gutters, pipes,12 and channels designed to efficiently move water offsite.13
Tagged Passions:sites, streets, utility, development, Utility, water, watershed, trees, Development, buildings and grounds, parking, and stormwater

Due to the continued increase in the stringency of stormwater management regulations, as14 outlined in Chapter 1, the inclusion of vegetated land and natural drainage pathways in site15 development designs has become more common. By including natural systems into their16 designs, developers can help offset the impact of urbanization on the stormwater system.17

Tagged Passions:regulation, development, Development, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

2.2.4 Effects of Development1 The development and redevelopment of urban and residential areas is necessary in the City as2 the economy and population continue to grow. Given that development will continue for the3 foreseeable future, the key is to consider the impacts that development will have on the4 landscape and receiving waterbodies. Chapter 3 through Chapter 8 of this document outlines5 the design, permitting, and construction standards that should be implemented to ensure that6 stormwater management is a major consideration in development going forward.7 As outlined in Section 2.1.4, changing a landscape from a natural condition to a developed8 condition also alters the hydrology of the site. By compacting the soil, installing roads, and9 constructing buildings, the overall impervious area of a site is dramatically increased. The10 reduction in evapotranspiration and infiltration, increase in impervious area, and traditional11 stormwater management principle of moving stormwater runoff offsite as fast as possible12 often lead to increased stream flow downstream of a development. This increased stream flow13 offsite can be seen in the increased runoff volume, peak runoff discharges, and runoff14 velocities. The high runoff rates and decreased infiltration rates caused by development also15 lead to decreases in groundwater recharge rate, which reduces the base flow in streams.16 Urbanization also leads to significant changes in the geometry of streams in a watershed.17 Traditionally, farmers and developers would straighten stream channels to reduce the area18 covered by a meandering stream channel and to increase the speed at which stormwater flows19 offsite. Additionally, the increase in runoff volume and velocity offsite increases the amount of20 channel forming bankfull and near bankfull events. Bankfull events are the flow condition where21 the highest stresses are applied to streambanks, causing streambank erosion and channel22 enlargement. Figure 2-3 shows a typical stream progression as a watershed is developed.23
Tagged Passions:construction, streets, agriculture, development, events, watershed, Development, buildings and grounds, rates, economy, and stormwater

24
Figure 2-3: Changes to a stream s geometry due to watershed development (Source: GA25

Stormwater Management Manual, 2016 Edition).26 The direct and indirect changes to the landscape following development have an impact on the27 aquatic habitats of these ecosystems. The increase in channel-forming bankfull events causes28 increased streambank erosion rates that undercut and uproot riparian vegetation. The29 streambed is scoured away as a result of more intense storm events that mobilize the native30 bed material downstream. In addition to the loss of valuable habitat along the streambank and31 bed, increased erosion causes higher sediment loads to downstream aquatic ecosystems. The32

Tagged Passions:development, events, watershed, Development, buildings and grounds, rates, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

additional sediment load often accumulates in downstream stream reaches and wetlands,1 degrading their aquatic habitat value. In wetlands, the higher runoff rates and volumes resulting2 from development cause greater fluctuations in water levels. Water levels fluctuating from3 extreme high levels to extreme low levels can stress wetland ecosystems causing a decline in4 aquatic plants and wildlife. Stormwater runoff from developed areas also has a higher5 temperature than runoff from natural landscapes. Aquatic organisms are typically sensitive to6 water temperatures, so the addition of warmer water from runoff can have a harmful effect on7 habitat diversity.8 Stormwater runoff due to development also increases the pollutant loads associated with9 runoff, degrading the water quality in aquatic resources. As stormwater runoff flows over10 developed areas, hydrocarbons from oil and gasoline, heavy metals, pesticides, and other11 pollutants are picked up and transported to receiving waters. Sediment contaminated by oil12 spills, pesticides, or construction operations also may discharge into receiving waters as a13 result of surface erosion from runoff. Green spaces (e.g., parks, recreational fields, gardens) in14 urbanized areas can be over fertilized or fertilized immediately prior to a rain event. The excess15 fertilizer is transported in stormwater runoff to bodies of water, increasing nutrient loads. The16 added nutrient load causes a rapid increase in the algal growth, which in turn increases nutrient17 competition for other organisms. In extreme cases, the increased algal growth can lead to algal18 blooms that can harm other plants, animals, and humans and lead to no oxygen being present19 in the water when the sun goes down.20 The increased stormwater runoff rates caused by development may also result in property21 damage and public safety concerns. Surface erosion around building foundations, scour22 around roadways, and streambank loss due to erosion are potential sources of property23 damage and safety concerns due to the increased stormwater runoff in developed areas.24 Additionally, algal blooms caused by increased nutrient loads in waterways can cause human25 health hazards.26 Surface runoff over roadways and parking lots often picks up and deposits loose trash and27 debris into rivers, ponds, and lakes. The discharge of trash into waterways and degradation of28 natural ecosystems contribute to a loss in the aesthetic value of the areas surrounding29 developments. The decline in wildlife abundance and diversity resulting from the loss and30 degradation of terrestrial and aquatic ecosystems also reduces the recreational value of these31 areas.32
Tagged Passions:health, construction, agriculture, utility, Fossil Fuels - Oil, development, Utility, public safety, events, water, watershed, plant, Development, buildings and grounds, pesticide, rates, diversity, parking, growth, recreation, and stormwater

2.3 Introduction to Soils33 Soils provide nutrients for plant growth, filtration of pollutants, and the storage or release of34 stormwater. The soil characteristics at a site should be considered when designing a35 development or redevelopment. Soil characteristics often dictate which practices are36

No additional detail provided

Tagged Passions:development, plant, Development, growth, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

Tagged Passions:stormwater

necessary for the management of stormwater during and after construction. Site factors that1 impact stormwater drainage include soil texture, soil permeability, vegetation, topography,2 groundwater levels, and climate. Based on these soil characteristics, one of four hydrologic soil3 groups (HSGs) are used to classify the infiltration rates of different soil units: Group A, Group B,4 Group C, and Group D. Additionally, characteristics such as the pH and organic content of soil5 influence the type of vegetation that can thrive at a particular site. The growth of vegetation on6 a site can help to stabilize the soil, improve infiltration, and promote pollutant removal from7 stormwater.8

Soils are generally made up of four main components: mineral elements; pore space, organic9 matter, and living organisms. Soil texture is determined by the concentration of the three sizes10 of mineral elements found in soil. From smallest to largest, these particles are clay, silt, and11 sand. Soils with a higher concentration of sand are considered coarse textured and tend to be12 well draining, have low nutrient content, and are highly erodible. A higher concentration of clay13 will result in fine-textured soils that have reduced air and water movement, tend to shrink and14 swell, and become slippery when saturated (Figure 2-4).15
Tagged Passions:construction, utility, Utility, water, environment, rates, growth, and stormwater

16
Figure 2-4: Soil Mineral Sizes (Source: Rain Machine Soil Types)17

Soil permeability is the measure of the ability of fluids to pass through soil. Permeability is18 determined based on a combination of soil texture, structure, and density. Soils with very low19 permeability have dense, clayey mineral elements restricting the movement of air and water20 between pores. Highly permeable soils have loose, sandy minerals allowing fluids to easily21

City of Charleston Stormwater Design Standards Manual Conceptual Overview

infiltrate into pore spaces. In terms of stormwater management, this characteristic is one of the1 main factors in determining how quickly an area will drain following a storm event. The ability,2 or in some cases inability, of water to infiltrate through soil may determine the design3 requirements for a development s stormwater management.4 While soil texture and permeability are important to site stormwater infiltration, many other site5 conditions and soil characteristics influence the overall drainage of a particular soil unit. To6 simplify the determination of soil infiltration rates, the NRCS classifies soils as one of four HSGs7 (Table 2-2). Group A is characterized by low runoff potential, high infiltration rates even when8 wetted, and large amounts of sand and gravel. Group B soils have moderate infiltration rates9 when wetted and are composed of fine to moderately coarse sand. Soils in Group C have low10 infiltration rates when wetted, have a layer that impedes the infiltration of water, and are11 composed of fine-textured soils. Group D soils have a high runoff potential, have low infiltration12 rates, and consist of clay soils with a permanent high water table or shallow soils over nearly13 impervious material. The infiltration rates for all of these hydrologic soil groups are reduced14 when the soil is saturated due to large storm events.15
Tagged Passions:utility, development, Utility, events, water, Development, rates, and stormwater

Table 2-2: Characteristics of NRCS Hydrologic Soil Group Classifications16 Soil Group Description Runoff Potential Infiltration Rate A Deep sandy soils Very low High B Shallow sandy soils over

low permeability layer Low Low C Sandy soil with high clay or mineral content Medium to high Low D Clayey soils Very high Low to none 17 The characteristics influencing the hydrologic soil groups are often site-specific; however, the18 addition of vegetation to a site design can stabilize the soil, improve infiltration, and promote19 pollutant removal from stormwater. Soil characteristics such as pH and organic content20 influence the ability for vegetation to grow in soil. Topsoil and compost can be added to the21 upper layer of the existing soil onsite to provide the nutrients and chemical composition for22 vegetation to establish.23 2.4 Water Quality24 The potential impacts to water quality should be considered when designing developments and25 redevelopments. Stormwater pollutants most often come from nonpoint sources, and are an26

Tagged Passions:utility, development, Utility, water, Development, and stormwater

City of Charleston Stormwater Design Standards Manual Conceptual Overview

indirect impact of land development. As stormwater runoff washes over streets and parking1 lots, garbage, vehicle-related chemicals, pesticides, and other debris are picked up and2 discharged into ditches and receiving waterbodies. Common pollutants associated with land3 development are provided in Table 2-3 and include suspended solids, oxygen demanding4 matter and bacteria, and nutrients. High levels of these pollutants in stormwater runoff can lead5 to multiple issues for receiving waterbodies, including reduced dissolved oxygen (DO) levels;6 increased algal growth, which may lead to eutrophication; and habitat degradation.7 Table 2-3: Typical stormwater pollutants and sources8 Pollutant Source Pollutants of Concern Erosion Sediments and attached soil nutrients, organic matter, and other adsorbed pollutants. Atmospheric Deposition Hydrocarbons emitted from automobiles, dust, metals, nutrients, and other chemicals released from industrial and commercial activities.
Tagged Passions:streets, agriculture, development, industrial, transportation, Development, commercial, pesticide, growth, and stormwater

Roadways/Transportation Related Areas

Hydrocarbons emitted from automobiles, dust, and metals. Construction Sites Sediment, metals, paint, and wood preservatives. Manufactured Products (Industrial Land Uses) Heavy metals, phenols, and oils from automobiles, and zinc and cadmium from tire wear. Lawn and Landscape Maintenance Fertilizer and pesticides. Plants and Animals Plant debris, grass clippings and animal excrement. Septic Tanks Coliform bacteria, nitrogen, and NO3. Non-Stormwater Connections Sanitary sewage, industrial wastewater, commercial discharge, swimming pool discharge, and water line flushing. Accidental Spills Pollutants of concern depend on the nature of the spill. Animal Waste Management Coliform bacteria, nitrates, and phosphorus. Pesticide Applications Pollutants of concern depend on the pesticide being used and the type of crop or pest being treated. Agricultural Land Disturbance Sediment and attached soil nutrients, organic matter, and other adsorbed pollutants. Fertilizer Applications Nitrogen and phosphorus.
Tagged Passions:construction, sewer, sites, agriculture, utility, Fossil Fuels - Oil, industrial, Utility, transportation, water, plant, buildings and grounds, commercial, pesticide, and stormwater

Source: U.S. Environmental Protection Agency, June 1992.9

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Tagged Passions:environment

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