3: storm water utility credit program

Land Development Land Development Ordinance ChangesOrdinance Changes

Greenville County, SC Greenville County, SC

PART 2PART 2

Clemson UniversityClemson UniversityICAR CampusICAR Campus

AT&T AuditoriumAT&T Auditorium

June 24, 2009June 24, 2009

Land Development Ordinance Changes – Greenville County, SC

SECTION 3: STORM WATER UTILITY

CREDIT PROGRAM

3: Storm Water Utility Credit 3: Storm Water Utility Credit ProgramProgram


Purpose Applicability Credit Schedule County Inspections Facility and BMP Maintenance Maintenance Agreement Facility/ BMP not in Dedicated

Easement Disqualifying Provisions



Purpose

Provide credits against Storm Water Service Fee for Class 2 properties (developed non-residential properties)

Encourage sound technical design practices and use of applicable storm water control facilities and water quality BMPs to reduce impact of development on drainage system and environment



Applicability

Class 2 property (developed non-residential

Approved, on-site, post-construction storm water control facility or water quality BMP

Facility/ BMP within a recorded sanitary sewer/ drainage easement (or equivalent restrictions to future changes in use)

Must have applicable permits



Applicability

Constructed in compliance with approved plans

Owner responsible for all O & M costs Maintained in compliance with

County standards County permitted access for

inspection No significant changes in land use or

impervious service within facility/ BMP service drainage area



Credit Schedule

Properties can qualify for:− Water Quantity Credits (up to 25%)− Water Quality Credits (up to 25%)

A total maximum of up to 25% credit against the Storm Water Service Fee

Credit applied by reducing the number of billable ERUs

Adjusted ERU includes credit for both water quantity and water quality

Minimum adjusted ERU is one (1)



Water Quantity Credits

Tree Preservation Policy Credit (up to 10%)

Upgrade Existing Detention/Retention Facility Credit (up to 15%)

Over-Detention Credit (up to 25%)

Discharge Elimination Credit (up to 25%)

Total Water Quantity Credit – NOT TO EXCEED 25%



Tree Preservation Policy Credits

Up to 10% credit for going above and beyond requirements of Greenville County Tree Ordinance

Preservation of natural undisturbed areas of at least 1 contiguous acre

Must meet standards to qualify for conservation use per SC Nature Conservancy guidelines



Tree Preservation Policy Credits

Must be recorded in restrictive covenants

Impervious surface runoff treated by stream buffers will also be considered for credit

Allow 1% credit for each acre of contiguous area up to 10%



Upgrade Existing Detention/ Retention Facility Credit

Up to 15% credit for reconstruction of existing detention/retention basins that comply with current storm water regulations

Engineer’s certification of compliance required



Over-Detention Credit

Up to 25% credit for detention/ retention of runoff in excess of current regulations

Engineer’s certification required Maximum credit per storm event allowed as

follows:− 100-year = 1%− 50-year = 2%− 25-year = 11%− 10-year = 6%− 2-year = 5%

Calculations must reflect a pre-development land use without development and/or prior land disturbing activities



Discharge Elimination Credit

Up to 25% credit for properties that do not discharge storm water runoff or pollutants to the County MS4

These areas treat, store, dispose, transpire, evaporate, infiltrate or otherwise manage runoff from all rainfall events up to and including 100-year

Engineer certification required



Water Quality Credits

New Development, New BMPs Credit (up to 10%)

Retrofit Existing Facility Credit (up to 25%)

Offsite Storm Water Quality Control Credit (up to 25%)

Total Water Quality Credit – NOT TO EXCEED 25%



New Development, New BMPs Credit

New Storm Water Quality Control BMP Credit = % impervious area of property routed through BMP x Water Quality Factor % x 0.10

Up to 10% credit for installing water quality facilities/ BMPs

BMPs designed in accordance with Greenville Co. Storm Water Design Manual

List of Approved BMPs – Appendix G of Design Manual




Water Quality Factors: available for approved BMPs in Appendix G of Design Manual

Innovative solutions encouraged (may require valid documentation from full scale testing by independent 3rd party for verification of pollutant removal efficiency)

Engineer’s Certification required (verifying that flow from the specified % of impervious area of property is routed through BMP)




APPROVED BMPS Water Quality Factor (%)NON-STRUCTURAL BMPSOpen vegetated conveyance systems 20Natural stream buffers 25Disconnected rooftop to pervious area 15Grass or alternative paving surfaces 15Natural Infiltration 65

STRUCTURAL BMPS – GENERAL APPLICATIONDry Detention Basin 65Wet Detention Pond 80Storm Water Wetlands 80Biofilter 65Media Filter 65Media Filter (Manufactured Devices) 65Hydrodynamic Device (Manufactured Devices) 35

STRUCTURAL CONTROLS – LIMITED APPLICATION Vegetated Filter Strip (L < 150 ft.) 20Vegetated Filter Strip (L > 150 ft.) 50Vegetated Channels and Swales 20



Retrofit Existing Facility Credit

Up to 25% credit allowed for retrofit of existing facilities to meet current standards

File credit application and obtain development permit prior to making changes

One credit application per parcel



Retrofit Existing Facility Credit

Site map prepared by SC licensed engineer or land surveyor showing key site characteristics

Storm water design analysis, H & H report, as-builts by SC licensed PE

Service fee credit for 5-year term Annual report and certification of

proper O & M



Offsite Storm Water Quality Control Credit

Offsite Storm Water Quality Control Credit = Offsite Drainage Area/ Onsite Drainage Area x Water Quality Factor % x 0.25

Up to 25% credit allowed if demonstrated that on-site storm water treatment facility adequately treats offsite runoff from one or more developed properties (for which no storm water control exists at time of application)

No credit granted for non-point source pollution control for offsite undeveloped properties



Offsite Storm Water Quality Control Credit

Offsite drainage area contiguous with onsite drainage area

No contractual BMP maintenance agreement between owners (notarized certification from licensed SC engineer)

At such time as offsite runoff is treated prior to draining to onsite BMP or maintenance agreement is executed between on-site and off-site parties, credit may be reevaluated for reduction or cancellation



Storm Water Service Fee Credit Application Form

Application Form available on Greenville County website at: http://www.greenvillecounty.org/land_development/pdf/sw_fee_credit_app_form.pdf

Credit application documentation requirements checklist

Credit calculation worksheets Engineer’s Certification sheets Maintenance Agreement



County Inspections

Periodic evaluations of facilities/ BMPs to ensure proper maintenance and function

Failure of evaluation will lead to NOV− Fee credit rescinded if adequate

corrections not made within specified timeframe

− Reapplication is required for reinstatement of credit (after one year waiting period)



Facility and BMP Maintenance

Prior to submittal of Credit Application:− Must be constructed in compliance with

approved plans− Functioning as intended− Properly maintained

Inspections by property owner’s engineer to be done using County provided forms

Annual report and certification of proper O&M required to maintain credit



Maintenance Agreement

Master Agreement for all types of storm water control facility or water quality BMP

Use for on-site facilities/ BMPs (between property owner and County)

Use for off-site facilities/BMPs (between applicant and facility/ BMP owner)




Storm Water Facility/ BMP Location Map

Legal Description of Facilities/ BMPs Long Term Maintenance Plan:

− BMP schematics− Schedule of inspections− List techniques to inspect and maintain

systems (Use documentation checklists provided by County on website - available for all approved BMPs)




Long Term Maintenance Plan (continued): − Describe where and how trash, sediment,

and other pollutants removed will be disposed

− Identify person(s) responsible for inspection and maintenance

− Provisions for permanent access and maintenance easements



Facility/BMP not Located in Dedicated Easement

May be allowed Applicant must enter into a

Maintenance Agreement with County Acceptance at discretion of County Contact County prior to requesting

Credit Application



Disqualifying Provisions

Development/ construction in floodplain

Development/ construction on slopes in excess of 15%

Siting on porous or erodible soil Excessive soil removal and

excavation Severe topography modifications



Disqualifying Provisions

Channelization Development in sensitive areas Clear cutting Excessive grading Windborne dust and soils Transfer of pollution by vehicles

and equipment



QUESTIONS ???



SECTION 4: CHANGES TO STORM

WATER DESIGN MANUAL

4: Changes to Storm Water Design 4: Changes to Storm Water Design ManualManual


List of Chapters with Major Changes

Ch.2.2 Engineer Minimum Plan Ch.2.3 Special Pollution Abatement

Permit Ch.3.1.2 Preferred Storm Water

Management Facilities Ch.3.1.3 Fee-in-lieu Ch.3.1.4 Minimum Preliminary Site

Development Plan Requirements

Ch.3.3.3 Storm Water Management Design Standards

Ch.3.3.4 Erosion & Sediment Control Design Standards

(Note: Items in blue discussed elsewhere in presentation.)




Ch.3.3.5 Single and Multi-Family Development Regulations

Ch.3.3.7 Storm Water Facility Ownership & Maintenance

Ch.3.4 Digital submittal requirements Ch.3.7 Performance Security Ch.3.9.8 Service Fee Credit Calculations Ch.3.9.9 Approved BMPs Ch.4.4 Easement Widths Ch.5.6 First Flush Water Quality

Volume Ch.7.2.3 Detention Structure Design Ch.8.4.8 Final Stabilization





Ch.9.4 Water Quality Regulations Ch.9.5 First Flush Water Quality

Volume Ch.9.10 Special Pollution Abatement

Permit Ch.10Low Impact Development Ch.12.2.2 Inspections During Construction Ch.12.3 Correction Orders Ch.12.6 Civil Citations Ch.12.7 Consent Process Ch.12.8 Criminal Penalties App. G Approved BMPs, Fee Credits




Ch.2.2 Engineer Minimum Plan

Small scope projects with design criteria requiring professional designer due to one of the following will submit an Engineer Minimum Plan:− Quantity control in place as part of large

common plan but quality control may or may not be in place and EPSC plan is required

− Redevelopment requires post-construction BMP upgrades and an EPSC plan

− Minor modification or reconstruction of existing facility/ BMP




Small scope projects with design criteria requiring professional designer due to one of the following will submit an Engineer Minimum Plan (continued):

− Site drains to 303(d) or TMDL waterbody or have potential impact requiring BMPs for correction of violation of grading without permit

− Project has negative downstream impacts− Site requires storm drain pipe or

alterations to existing pipe




Application, permit process same as Non-Simplified Plan except for design criteria and fees

Minimum design criteria set on case-by-case basis during pre-design meeting

Fees are same as Simplified Permit




Plans require oversight by Design Professional

CEPSCI inspections and engineer of record certification may be required

Plan may be forwarded to SCDHEC for general permit based on disturbed area and if part of larger common plan



Ch.3.1.3 Fee-in-lieu

Ordinance language additions are presented in Part 1 of presentation. (Ordinance Location: Division 1 – Storm Water Management, Sec. 8-78. Fee-In-Lieu.)

Additional guidance is provided in Design Manual:− Purpose− Application− Criteria− Procedures




Purpose: To allow payment of a fee-in-lieu of providing storm water detention on a development site: − At sites where county intends to

construct downstream storm water conveyance upgrades or regional controls, or

− To encourage use of LID practices




Application: − Larger sites:

• Prove no downstream impacts• Be in specified watersheds where county

intends to construct storm water conveyance upgrades or regional controls

− Sites with < 1 acre impervious: • Preferred method• Fee waived if LID used

− Certain practices required (enhanced infiltration with permeable pavements, bio-swales, bio-retention cells, rain gardens, storm water harvesting and reuse, green roofs)




Criteria:− Modeling shows on-site detention results

in unfavorable downstream impacts (increase in peak discharge, flooding depth, erosion, water quality)

− Runoff from area is controlled via regional, county maintained conveyance system, storage and water quality enhancements

− Site with one acre or less impervious area, or with a flow increase of 1 or more cfs




Criteria (continued):− MS4 conveyance and natural system

provide adequate capacity and demonstrate no adverse effects to all upstream, adjacent and downstream properties in full build out watershed conditions

− Development adds a minimum of 5,000 square feet of impervious area (does not apply to individual residential homes, separately built)




Criteria (continued):− Development located in watershed

where model and master plan exists for impact evaluation purposes (currently: Gilder/Horsepen Creek, Brushy Creek, Rocky Creek, and Reedy River)

− Can show site specific controls constitute a hardship case and fee-in-lieu is only option

− Proposals presented during pre-design meeting

− Fee paid prior to issuance of land disturbance or grading permit




Procedures:− For requiring and collecting fee-in-lieu of

revenues: • Submit written request (will be rejected

or approved within 45 days unless additional engineering studies are required)

• Fee-in-lieu = estimated construction cost of proposed and approved on-site storm water storage, including land costs

− County maintained fund for identifying and controlling all revenues and expenditures resulting from fee-in-lieu approvals.




Procedures (continued):− Revenues received from each watershed

to be deposited in these funds for use within that watershed

− Revenues may be used to plan, design or construct upgrade to existing or future storm water management systems if upgrades are consistent with a storm water master plan, floodplain study or storm water system improvement approved by Director



Ch.3.1.4 Minimum Preliminary Site Development Plan

All Site Development Plan Requirements, as listed in revised Ordinance Sec. 8-68, have been added to Design Manual in Ch.3.1.4.

The only revisions to Site Development Plan Requirements in Ordinance are (also discussed in Part 1 of presentation):− Plans must meet all other applicable plan

requirements in effect at time of submittal



Ch.3.1.4 Minimum Preliminary Site Development Plan

The only revisions to Site Development Plan Requirements in the Ordinance are (continued):− Requires a tree saving and planting plan

consistent with GC Tree Ordinance and Landscape Plan requirements of Design Manual

− Certification that land clearing, construction, development and drainage done in accordance with approved plans

− Approved plans remain valid for 2 or 5 years (depending on fee paid)



Ch.3.4 Digital Submittal Requirements

Submit electronic copy of plans with preliminary approval per Greenville County’s Electronic Submission Standards and Procedures posted at: http://www.greenvillecounty.org/land_development/Planning.asp

Will be used only for anonymous inclusion in GC GIS

Submit drawings in DWG or DXF format to County’s ftp site or on approved standard storage media

Land disturbance permit will not be issued until electronic submittal has been received and approved



Ch.4.4 Easement Widths

Total easement width (permanent and temporary) sufficient to allow contractor flexibility in construction

No excessive widths requiring needless clearing/ cutting of wooded/ vegetated areas

Provide minimum requirements:− Adequate access to drainage system and structures− Sufficient land area for maintenance equipment and

personnel to adequately and efficiently maintain drainage system and storm water facilities;

− Prohibit all fences and structures that interfere with access and/or maintenance function



Ch.7.2.3 Detention Structure Design

General Design Criteria:− Criteria to ensure long term function of

structure while minimizing maintenance responsibilities

− Includes criteria for: basins on slopes; inlet and outlet locations; inlet design; relationship to groundwater; scour; access; outlet protection; minimum buffer/ setback; safety fence




Surface Detention Design Criteria:− Includes criteria for: basin side slopes;

basin shape; dry detention bottom slopes; underdrains, permanent pools; emergency spillways (location, exit channel grade); Safe Dams Act; principal spillways (trash racks, seepage control, anti-flotation)




Subsurface Detention Design Criteria:− Includes criteria for: emergency

spillways; pretreatment; observation wells; access port




Landscaping Criteria:− Criteria established to ensure

engineering function is protected− Criteria included for: types of

vegetation; spacing of plantings; location of plantings; side slopes; soil types; maintenance



Ch.9.4 Water Quality Regulations

Minimum Water Quality Requirements:− All storm water runoff generated from a

site to be adequately treated before discharge

− Presumed compliance if:• Preferred method – size water quality

device to trap 85% of TSS based on annual loadings by particle class (use IDEAL to model)

• Alternative as default criteria – size device to capture First Flush (first inch of runoff from site impervious area) and discharge over 24-hrs




Minimum Water Quality Requirements:− Appropriate structural storm water

controls or non-structural practices are selected, designed, constructed or preserved, and maintained according to the specific criteria in this manual

− More stringent controls may be required in environmentally sensitive areas

− All development/ redevelopment projects disturbing > 1 and resulting in > 1 cfs increase in peak runoff to meet these requirements even if no change in land use




IDEAL Model:− The Greenville County IDEAL Model or

other models such as the USEPA SWMM or Overflow Rate Model may be used to design BMPs to meet 85% TSS removal requirement

− Updated IDEAL Users Manual available on Greenville County website describes how to use the model to design several BMPs to this standard




IDEAL Model:− Updated IDEAL Users Manual includes:

• Trapping Efficiency Curves for Engineered Storm Water Quality Devices

• Method for calculating trapping efficiency for treatment trains (multiple BMPs in series or in parallel)



Ch.9.5 First Flush

Same as First Flush design requirements described in Ch.9.4. Water Quality Regulations, Minimum Water Quality Requirements



Ch.10 Low Impact Development

What is LID? − An ENGINEERING design approach to

STORMWATER MANAGEMENT focusing on mimicking natural state hydrologic regime through infiltration, separation, filtration, evaporation, retention, and detention.

− Synonymous with USEPA’s Green Infrastructure or Better Site Design

− LID attempts to offset environmental impacts of development by copying nature




What LID is NOT:− LEED (Leadership in Energy and

Environmental Design)− Smart Growth− New Urbanism− Sustainable development

… but is a potential element in all of these.




Basic Principles of LID:− Minimization of impact− Conservation of ecological and natural

resources− Maintain predevelopment runoff

patterns− Source control of runoff and pollution− Public/property owner education and

buy-in− Economic feasibility




Common Impacts of Land Development:− Increased storm water runoff volumes,

rates, and pollutant transport− Higher pollutant loads (sediment/debris,

fertilizers, SSOs, and leaks)− Modification of natural

streams/floodplains− Reduced biodiversity




How Do We Maintain Pre-Development Conditions?− Reduce Limits of Clearing and Grading

• Preserve existing trees• Preserve permeable soils• Preserve vegetated areas (especially

trees)− Site Fingerprinting

• Minimize disturbance• Re-vegetate

− Maintain flow pathways for large events




Preserve and Maintain Predevelopment Runoff Volume:− Reduce impervious surfaces− Disconnect impervious surfaces− Reduce road widths− Use retention and rainwater harvesting− Promote infiltration (e.g., porous pavers)




Preserve and Maintain Predevelopment Runoff Velocity: − Use open swales instead of pipe− Increase roughness − Flatten slopes and widen swales− Lengthen flow path



QUESTIONS ???


3: storm water utility credit program

Documents

total water quantity

water qualityminimum

storm water service

water quality credits

storm event

water quality bmps

discharge elimination

water quality bmpfacility