| 3.1 |
Introduction |
3-1 |
| 3.2 |
Federal
Regulations |
3-1 |
| 3.2.1 |
Phase I NPDES
Stormwater Permits |
3-2 |
| 3.2.2 |
Phase II NPDES
Stormwater Permits |
3-2 |
| 3.2.3 |
Endangered
Species Act |
3-3 |
| 3.3 |
State
Regulations |
3-6 |
| 3.3.1 |
Phase I NPDES
and State Waste Discharge Stormwater Permits for Municipalities |
3-6 |
| 3.3.2 |
Phase II NPDES
and State Waste Discharge Stormwater Permits for Municipalities |
3-7 |
| 3.3.3 |
The Puget Sound
Water Quality Management Plan |
3-7 |
| |
Local
Government Planning and Stormwater Programs (SW-1) |
3-7 |
| |
Stormwater
Technical Manual (SW-2.1) |
3-8 |
| 3.4 |
County
Regulations |
3-9 |
| 3.5 |
Town
Regulations |
3-9 |
| 3.6 |
Washington
State Department of Transportation Regulations |
3-10 |
| 3.7 |
Jurisdictional
Coordination |
3-10 |
| 4.1 |
Introduction |
4-1 |
| 4.2 |
Drainage System
Inventory for Model |
4-2 |
| 4.2.1 |
Drainage Basin
No. 1 |
4-2 |
| 4.2.2 |
Drainage Basin
No. 2 |
4-3 |
| 4.2.3 |
Drainage Basin
No. 3 |
4-3 |
| 4.2.4 |
Drainage Basin
No. 4 |
4-4 |
| 4.2.5 |
Drainage Basin
No. 5 |
4-5 |
| 4.2.6 |
Drainage Basin
No. 6 |
4-5 |
| 4.2.7 |
Drainage Basin
No. 7 |
4-6 |
| 4.3 |
Hydrologic/Hydraulic Modeling |
4-6 |
| 4.3.1 |
Design Storm |
4-7 |
| 4.3.2 |
Runoff
Parameters |
4-8 |
| 4.3.2.1 |
Drainage Basin
Area |
4-8 |
| 4.3.2.2 |
CN Values |
4-8 |
| 4.3.2.3 |
TC
Values |
4-9 |
| 4.3.3 |
Computer
Applications/Hydra Model |
4-10 |
| 4.3.4 |
Model
Calibration/Verification |
4-19 |
| 4.4 |
Model Results |
4-19 |
| 4.4.1 |
Drainage Basin
No. 1 Model Results |
4-20 |
| 4.4.2 |
Drainage Basin
No. 2 Model Results |
4-20 |
| 4.4.3 |
Drainage Basin
No. 3 Model Results |
4-21 |
| 4.4.4 |
Drainage Basin
No. 4 Model Results |
4-22 |
| 4.4.5 |
Drainage Basin
No. 5 Model Results |
4-23 |
| 4.4.6 |
Drainage Basin
No. 6 Model Results |
4-24 |
| 4.4.7 |
Drainage Basin
No. 7 Model Results |
4-24 |
| 4.5 |
Town Identified
Stormwater Problem Areas |
4-25 |
| 4.6 |
Previous
Hydraulic Studies |
4-26 |
| 5.1 |
Introduction |
5-1 |
| 5.2 |
Impacts to
Water Quality |
5-1 |
| 5.3 |
Water Quality
Standards |
5-3 |
| 5.3.1 |
Parameters of
Concern |
5-4 |
| 5.3.2 |
Water Quality
Criteria |
5-7 |
| 5.4 |
Existing
Background Water Quality Surveys |
5-9 |
| 5.5 |
Sources of
Nonpoint Pollutants |
5-9 |
| 5.5.1 |
Urban
Development |
5-10 |
| 5.5.2 |
County and
State Highways |
5-11 |
| 5.6 |
General
Considerations in Urban Stormwater Quantity and Quality Control |
5-12 |
| 5.6.1 |
Stormwater
Quality versus Quantity Control |
5-13 |
| 5.6.2 |
Construction
Phase versus Long-Term Site Operation Phase |
5-13 |
| 5.6.3 |
Structural
versus Nonstructural Controls |
5-13 |
| 5.6.4 |
Source Control
versus Downstream Treatment |
5-14 |
| 5.6.5 |
Control in New
versus Existing Developments |
5-14 |
| 5.6.6 |
Control of
Acute versus Chronic Impacts |
5-14 |
| 5.6.7 |
Special
Sensitive Area Considerations |
5-14 |
| 5.7 |
Stormwater
Management Alternatives |
5-14 |
| 5.7.1 |
Structural
Alternatives |
5-15 |
| 5.7.1.1 |
Storage and
Regulated Release |
5-15 |
| 5.7.1.2 |
Minimize
Directly Connected Impervious Area |
5-16 |
| 5.7.1.3 |
Swales and
Filter Strips |
5-17 |
| 5.7.1.4 |
Parking Blocks |
5-18 |
| 5.7.1.5 |
Infiltration
Devices |
5-18 |
| 5.7.1.6 |
Summary |
5-20 |
| 5.7.2 |
Non-Structural
Alternatives |
5-21 |
| 5.7.2.1 |
Facilities
Maintenance |
5-21 |
| 5.7.2.2 |
Changes to
Municipal Codes and Regulations |
5-23 |
| 5.7.2.3 |
Enforcement |
5-24 |
| 5.7.2.4 |
Public
Involvement and Education |
5-24 |
| 5.7.2.5 |
Best Management
Practices |
5-26 |