Gwinnett County’s Post Gwinnett County’s Post Development Stormwater Development Stormwater

Management ProgramManagement Program

Three Stage of Stormwater Three Stage of Stormwater ManagementManagement

Stage One: Plan ReviewStage One: Plan Review– Approve designsApprove designs– Assure proper erosion and sediment controlAssure proper erosion and sediment control– Check calculations and drainage areas Check calculations and drainage areas – Make necessary comments for revisionMake necessary comments for revision

Stage Two: DevelopmentStage Two: Development– Conducts detention pond inspectionsConducts detention pond inspections– Assure compliance with codes and regulationsAssure compliance with codes and regulations– Issue violations and finesIssue violations and fines

Stage Three: Post DevelopmentStage Three: Post Development– Maintenance of infrastructureMaintenance of infrastructure– Citizen complaints Citizen complaints – Post development detention pond inspectionsPost development detention pond inspections– Compile post development statisticsCompile post development statistics

Post Development Post Development Customer ServiceCustomer Service

– Drainage ComplaintsDrainage Complaints

Construction & MaintenanceConstruction & Maintenance– County Crews and Demand ContractorsCounty Crews and Demand Contractors

Engineering DepartmentEngineering Department– Creates the Designs for County ProjectsCreates the Designs for County Projects

Watershed ImprovementWatershed Improvement – Watershed Assessments and Stream RestorationWatershed Assessments and Stream Restoration

Environmental ComplianceEnvironmental Compliance– Illicit Discharge and Water Quality MonitoringIllicit Discharge and Water Quality Monitoring

Customer ServiceCustomer Service

Gwinnett County maintains all the pipes and structures Gwinnett County maintains all the pipes and structures within and connected to the Public right-of-way*within and connected to the Public right-of-way*– *Do not maintain drainage structures on commercial property*Do not maintain drainage structures on commercial property– *Do not maintain drainage structure within city limits, except Lilburn*Do not maintain drainage structure within city limits, except Lilburn

Citizens may call or go on-line to report a problemCitizens may call or go on-line to report a problem– Broken structuresBroken structures– Clogged pipesClogged pipes– Failed pipeFailed pipe– Siphon holesSiphon holes– Illicit discharge, part of environmental complianceIllicit discharge, part of environmental compliance

Broken StructuresBroken Structures

Clogged StructuresClogged Structures

Failed PipeFailed Pipe

Siphon HolesSiphon Holes

Investigative ToolsInvestigative Tools

GIS data is extremely helpfulGIS data is extremely helpful The Final Plat is the official record of The Final Plat is the official record of

property and inventoryproperty and inventory Our camera is definitely the most useful toolOur camera is definitely the most useful tool Basic equipment- Gloves, manhole hook, Basic equipment- Gloves, manhole hook,

safety vest, flashlight, and map book safety vest, flashlight, and map book

InvestigationsInvestigations

Construction and MaintenanceConstruction and Maintenance

Service ticket is turned inService ticket is turned in Construction manager assigns projectConstruction manager assigns project

– County work crewsCounty work crews– Demand ContractorDemand Contractor

List completed by priorityList completed by priority– Emergencies firstEmergencies first– Received dateReceived date

Construction ProjectConstruction Project

Lining ContractorLining Contractor

Finishing UpFinishing Up

Cost of ProjectCost of Project

Lined 467 feet of pipe, replaced 1 headwall, Lined 467 feet of pipe, replaced 1 headwall, and rocked ditchesand rocked ditches

Estimated Cost $214,000Estimated Cost $214,000 Actual Cost $142,000Actual Cost $142,000 Cost per foot Cost per foot ≈ $304.07≈ $304.07

Replacement ProjectReplacement Project

Impact of CollapseImpact of Collapse

ExcavationExcavation

New SystemNew System

Finishing UpFinishing Up

Cost of ProjectCost of Project

Replaced approximately 100 ft. of pipeReplaced approximately 100 ft. of pipe Set two new junction boxesSet two new junction boxes Replaced water vault and relocated sewer Replaced water vault and relocated sewer

lineline Excavation and repavingExcavation and repaving Estimated Construction $325,000 Estimated Construction $325,000 Actual Cost ???Actual Cost ??? Cost per foot Cost per foot ≈ $3,250≈ $3,250

Cost Benefit for DeveloperCost Benefit for Developer

Always the bottom lineAlways the bottom line Do the bare minimum Do the bare minimum Use the cheapest pipe possibleUse the cheapest pipe possible

– HDPE: 18”x20’ $141.20HDPE: 18”x20’ $141.20 Cost per foot $7.06 Cost per foot $7.06– CMP: CMP: 18”x20’ $250.80 18”x20’ $250.80 Cost per foot $12.54 Cost per foot $12.54– RCP:RCP: 18”x8’ $110.88 18”x8’ $110.88 Cost per foot $13.86 Cost per foot $13.86

Installation costs are much lower with the Installation costs are much lower with the CMP*CMP*

Gwinnett County InfrastructureGwinnett County Infrastructure

Gwinnett County is 437 square milesGwinnett County is 437 square miles Population of nearly 800,000Population of nearly 800,000 Approx. 2,091.5 miles of stormwater pipesApprox. 2,091.5 miles of stormwater pipes

– 53.4% Corrugated Metal53.4% Corrugated Metal– 25.6% Aluminized Steel 25.6% Aluminized Steel – 18.8% Reinforced Concrete18.8% Reinforced Concrete– 2% HDPE/PVC2% HDPE/PVC– .2% Miscellaneous .2% Miscellaneous

Gwinnett maintains 1,296.2 milesGwinnett maintains 1,296.2 miles Approx. 178,914 stormwater structuresApprox. 178,914 stormwater structures Gwinnett Maintains 111,575 structures Gwinnett Maintains 111,575 structures

Gwinnett County Strategic Asset Gwinnett County Strategic Asset Management PlanManagement Plan

““To plan, create, acquire, maintain, operate, rehabilitate, replace and To plan, create, acquire, maintain, operate, rehabilitate, replace and dispose of assets in the most cost-effective manner while providing dispose of assets in the most cost-effective manner while providing established level of service for present and future generations.”established level of service for present and future generations.”

Rate or grade pipes and/or pipe systems on the following criteriaRate or grade pipes and/or pipe systems on the following criteria– Corrosive SoilsCorrosive Soils– Age, % of remaining useful lifeAge, % of remaining useful life– MaterialMaterial– Number of Recorded FailuresNumber of Recorded Failures– Maintenance HistoryMaintenance History

Goal: Ensure that desired service levels and other operational Goal: Ensure that desired service levels and other operational objectives are achieved at optimal cost. objectives are achieved at optimal cost.

Affects of UrbanizationAffects of Urbanization

Lake HavenLake Haven

Lake Haven Lake Haven

Post ConstructionPost Construction

Total cost including engineering Total cost including engineering and construction $426,805and construction $426,805

Illicit DischargeIllicit Discharge