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TRANSCRIPT
Jadene Torrent Stensland, PE Senior Water Resources Engineer
North Bethany Area
Storm Implementation Plan
Jadene Torrent Stensland, PE
Senior Engineer
Water Resources
OBJECTIVES
• BACKGROUND
• HISTORY
• DRAINAGE MASTER PLAN
• IMPLEMENTATION PLAN
• DESIGNS
• LIDA REDUCTIONS
• COST ESTIMATES
BACKGROUND
• Clean Water Services
Washington County Special Service District
Over 40 years of service
Urban Sanitary and Stormwater Management
Natural Resource Management
Serve population 527,000+ residents
BACKGROUND
• North Bethany Sub Area
Planning began over 10 years ago
800 acres, rural and ag
458 developable acres
3650 – 4750 new dwelling units
Area of Distinction
Sustainability
Parks and Trails
Utilities Planning
North Bethany Area Map
History
• Drainage Master Plan
Complete in December 2010
Concept Planning Document
Design Criteria
Storm System concept layout
Preliminary Cost Estimates
Linear Storm Water System and Trails
Otak 2010 DMP
Greenworks 2009 Sketch
Implementation Plan
• North Bethany Implementation Plan
Regional Facilities
Major Conveyance System
30% Designs
Cost Estimates
Regional Facility Sizing
Facility Concepts 1. Conventional Extended Dry Basin (round design)
2. Linear Extended Dry Basin (cascade design)
3. Implementation Options for Upstream LIDA
Conventional Extended Dry Basin
Regional Stormwater Facility Design Criteria
Design Criteria* District
Maximum Depth 4.0 feet
Maximum Ponding Depth 3.0 feet
Freeboard 1.0 feet
Amended Soils 1.0 feet
Side Slopes (in treatment area) (H:V) 3:1
Overflow (Y/N) Y
Native Plantings Y
Fencing Y
* Locate facilities outside of the
stream and vegetated corridor
(vc).
Extended Dry Basin
Facility Design Alternatives
Conventional Extended Dry Basin
Linear Extended Dry Basin
Regional Stormwater Facility Design Criteria
Design Criteria Value
Maximum Depth 4.0 feet
Maximum Ponding Depth 3.0 feet
Freeboard 1.0 feet
Amended Soils 1.0 feet
Minimum Bottom Width 8 feet
Side Slopes (in treatment area) (H:V) 3:1
Bottom Slope 0.5%
Overflow (Y/N) Y
Native Plantings Y
Fencing Y
Cascade Storm Water System
Otak 2010 DMP
Greenworks 2009 Sketch
Facility Design Alternatives
Linear Extended Dry Basin Example (cascade)
Facility Design Alternatives
Linear Extended Dry Basin Example (cascade)
3. Credit for Upstream LIDA
Areas Where Site LIDA is Required
3. Credit for Upstream LIDA
Assumptions for LIDA
3. Credit for Upstream LIDA
Impact to Regional Facility Size
2
0
10000 15000 20000 25000 30000 35000 40000
7. LIDA Planter with Orifice to Meet Hydromod Stds. (100% LIDA)
6. LIDA Planter Current Requirements (100% LIDA)
5. LIDA Planter with Orifice to Meet Hydromod Stds. (Mandatory LIDAAreas Only)
4. LIDA Planter With Deeper Growing Medium (Mandatory LIDAAreas Only)
3. LIDA Planter Current Requirements (Mandatory LIDA Areas Only)
2. LIDA Swale (Mandatory LIDA Areas Only)
1. Regional Facility Only (No LIDA)
Regional Facility Surface Area (sq-ft)
3. Credit for Upstream LIDA
Regional Facility Sizing Reduction Factors
2
1
Round Extended Detention Facility
Subbasin
Impervious Area Treated
by Mandatory LIDA
(acres) Facility Size (ft2)
Facility Area
Reduction/Impervious Acre
Treated by LIDA (ft2)
BT3
0 20,146
582 7.0 16,074
BT2 and BT3
0 45,705
554 11.0 39,611
Linear Detention Facility
Subbasin
Impervious Area Treated
by Mandatory LIDA
(acres) Facility Size (ft2)
Facility Area
Reduction/Impervious Acre
Treated by LIDA (ft2)
BT3
0 28,758
423 7 25,800
BT4
0 4,816
406 3.4 3,440
Facility
ID
Subbasin
name
Total
contributing
area,
acres
Impervious
area,
acres
RSF top area
at 4-foot
depth,
sq ft
RSF top area
50% Implementation of
LIDA
sq ft
RSF top area
100% Implementation of
LIDA
sq ft
1 AB1 34.7 18.4 33,024 30,261 27,499
2 AB2 32.0 17.8 19,772 16,265 12,759
3 AB4 42.1 21.0 25,613 21,441 17,268
4 AB6 29.9 14.3 25,800 23,965 22,130
5 AB8 33.3 22.4 15,612 13,690 11,767
6 AB9 59.8 40.1 22,708 18,932 15,155
7 AB10 19.4 10.2 15,480 13,692 11,905
8 AB11 33.7 16.8 33,540 30,352 27,164
9 AB12 28.4 14.7 25,800 23,855 21,909
10 BT2 & BT3
combined 46.5 28.0 39,611 35,316 31,021
11a BT3 26.8 16.4 16,074 13,663 11,252
11b BT3 26.8 16.4 25,800 24,046 22,293
12 BT4 14.9 6.8 3,440 2,749 2,058
13 BT5 7.3 5.0 4,472 4,092 3,712
14 BT6 16.4 8.5 5,848 4,448 3,048
15 BT8 9.4 4.6 3,096 2,297 1,498
16 RU3 71.3 37.7 44,340 35,617 26,894
17 RU5 29.8 18.6 19,850 16,975 14,100
3. Credit for Upstream LIDA
Sizing Reduction Factors
4. Analysis of Alternative LIDA
Configurations
2
3
4. Analysis of Alternative LIDA
Configurations
2
4
LIDA
Configuration
LIDA Planter as
Shown in the
Manual
LIDA Planter
Plus Additional
Growing Media
LIDA Planter
Plus Additional
Ponding
LIDA Planter Plus
Ponding and
Growing Media and
Unlined
LIDA Planter
Plus Growing
Media and
Unlined
LIDA Planter
Plus Ponding
and Growing
Media and Dead
Storage and
Unlined
LIDA Planter
Plus Ponding
and Growing
Media and No
Underdrain and
Unlined
Max Ponding
Depth (in) 6 6 12 12 6 12 12
Growing Media
Depth (in) 18 24 18 24 30 30 30
Drain Rock Layer
Depth (in) 12 12 12 12 12 15 12
Dead Storage (in) 3 3 3 3 3 6 12
Lined Yes Yes Yes No No No No
INFILT Value for
Facility (in/hr) NA NA NA 0.2 0.2 0.2 0.2
Sizing Factor
(%Impervious
Area) 31.5% 12% 16.5% 8.5% 7.25% 6.75% 6.4%
Total Facility
Depth (ft) 3.17 3.67 3.67 4.17 4.17 4.92 4.67
5. Results - Overview of Regional
Facility Layout
• Required design elements:
Must meet District D&C Standards.
Footprint must match preliminary design.
Outflow restriction (orifice) must match
preliminary design.
• Flexibility in design:
Location of facility.
The District is open to alternative designs that
meet minimum requirements.
Modified LIDA to address water quantity.
5. Results
5. Results (example Preliminary Design)
5. Results (preliminary design)
5. Results - Costs
Questions and
General Discussion
Contact:
Jadene Stensland, PE
Phone: 503-681-3662
Email: [email protected]