1. Gwinnett County’s Post Development Stormwater Management Program

2. Three Stage of Stormwater Management
Stage One: Plan Review
Approve designs
Assure proper erosion and sediment control
Check calculations and drainage areas
Make necessary comments for revision
Stage Two: Development
Conducts detention pond inspections
Assure compliance with codes and regulations
Issue violations and fines
Stage Three: Post Development
Maintenance of infrastructure
Citizen complaints
Post development detention pond inspections
Compile post development statistics

3. Post Development Customer Service Construction & Maintenance
Drainage Complaints
Construction & Maintenance
County Crews and Demand Contractors
Engineering Department
Creates the Designs for County Projects
Watershed Improvement
Watershed Assessments and Stream Restoration
Environmental Compliance
Illicit Discharge and Water Quality Monitoring

4. Customer Service
Gwinnett County maintains all the pipes and structures within and connected to the Public right-of-way*
*Do not maintain drainage structures on commercial property
*Do not maintain drainage structure within city limits, except Lilburn
Citizens may call or go on-line to report a problem
Broken structures
Clogged pipes
Failed pipe
Siphon holes
Illicit discharge, part of environmental compliance

5. Broken Structures

6. Clogged Structures

7. Failed Pipe

8. Siphon Holes

9. Investigative Tools GIS data is extremely helpful
The Final Plat is the official record of property and inventory
Our camera is definitely the most useful tool
Basic equipment- Gloves, manhole hook, safety vest, flashlight, and map book

10. Investigations

11. Construction and Maintenance
Service ticket is turned in
Construction manager assigns project
County work crews
Demand Contractor
List completed by priority
Emergencies first
Received date

12. Construction Project

13. Lining Contractor

14. Finishing Up

15. Cost of Project
Lined 467 feet of pipe, replaced 1 headwall, and rocked ditches
Estimated Cost $214,000
Actual Cost $142,000
Cost per foot ≈ $304.07

16. Replacement Project

17. Impact of Collapse

18. Excavation

19. New System

20. Finishing Up

21. Cost of Project Replaced approximately 100 ft. of pipe
Set two new junction boxes
Replaced water vault and relocated sewer line
Excavation and repaving
Estimated Construction $325,000
Actual Cost ???
Cost per foot ≈ $3,250

22. Cost Benefit for Developer
Always the bottom line
Do the bare minimum
Use the cheapest pipe possible
HDPE: 18”x20’ $ Cost per foot $7.06
CMP: 18”x20’ $ Cost per foot $12.54
RCP: 18”x8’ $ Cost per foot $13.86
Installation costs are much lower with the CMP*

23. Gwinnett County Infrastructure
Gwinnett County is 437 square miles
Population of nearly 800,000
Approx. 2,091.5 miles of stormwater pipes
53.4% Corrugated Metal
25.6% Aluminized Steel
18.8% Reinforced Concrete
2% HDPE/PVC
.2% Miscellaneous
Gwinnett maintains 1,296.2 miles
Approx. 178,914 stormwater structures
Gwinnett Maintains 111,575 structures

24. Gwinnett County Strategic Asset Management Plan
“To plan, create, acquire, maintain, operate, rehabilitate, replace and dispose of assets in the most cost-effective manner while providing established level of service for present and future generations.”
Rate or grade pipes and/or pipe systems on the following criteria
Corrosive Soils
Age, % of remaining useful life
Material
Number of Recorded Failures
Maintenance History
Goal: Ensure that desired service levels and other operational objectives are achieved at optimal cost.

25. Affects of Urbanization

26. Lake Haven

27. Lake Haven

28. Total cost including engineering and construction $426,805
Post Construction
Total cost including engineering and construction $426,805

29. Illicit Discharge