HomeMy WebLinkAboutNotes Applicant 12/9/2024 (7)Favreau Engineering, LLC
2206 Country Haven Dr
Eugene, OR 97408
(541) 556-4425
DRAINAGE AREA =3,035 SQ. FT. = 0.070 ACRES
AVERAGE RUNOFF COEFFICIENT (C) = 0.90
LENGTH OF DRYWELL = 40 FEET
WIDTH OF DRYWELL = 8 FEET
DEPTH OF DRYWELL = 6 FEET
VOID RATIO OF DRYWELL =35%
AVERAGE PERMEABILITY OF SOIL = 1.50 INCHES/HR
SURFACE AREA OF BOTTOM =320 SQ. FT.
SURFACE AREA OF SIDES =576 SQ. FT.
OUTFLOW CAPACITY OF DRYWELL = 40.0 CU. FT./HR = 4.99 GALLONS PER MINUTE
MAXIMUM STORAGE CAPACITY OF DRYWELL = 672 CU. FT. OF WATER
DRYWELL VOLUME = 71.1 CUBIC YARDS
10 YEAR TOTAL
RECURRENCE RAINFALL TOTAL OUTFLOW
DURATION DURATION RAINFALL DURING STORM EVENT FROM STORAGE
OF STORM OF STORM INTENSITY STORM RUNOFF DRYWELL REQUIRED DRYWELL
IN MINUTES IN HOURS IN/HR INCHES CU. FT. CU. FT. CU. FT. SIZING
5 0.08 3.10 0.26 59 3 55 OK
10 0.17 2.10 0.35 80 7 73 OK
15 0.25 1.65 0.41 94 10 84 OK
20 0.33 1.40 0.47 106 13 93 OK
30 0.50 1.10 0.55 125 20 105 OK
60 1.00 0.70 0.70 159 40 119 OK
120 2.00 0.50 1.00 228 80 148 OK
180 3.00 0.44 1.32 300 120 180 OK
240 4.00 0.41 1.64 373 160 213 OK
360 6.00 0.36 2.16 492 240 252 OK
480 8.00 0.32 2.56 583 320 263 OK
600 10.00 0.28 2.80 637 400 237 OK
720 12.00 0.25 3.00 683 480 203 OK
900 15.00 0.21 3.15 717 600 117 OK
1,080 18.00 0.20 3.60 819 720 99 OK
1,260 21.00 0.19 3.99 908 840 68 OK
1,440 24.00 0.18 4.32 983 960 23 OK
1,800 30.00 0.17 5.10 1,161 1,200 EMPTY OK
SOAKAGE TRENCH CALCULATIONS FOR
503 17th St, Springfield - Roof Runoff
See Infiltration Report by:
Attached
Page 1 of 1
SOAKAGE TRENCH NOTES:
1. SOAKAGE TRENCH = 40' x 8' x 6' OR EQUIVALENT SQUARE FOOTAGE.
2. TOTAL IMPERVIOUS AREA DRAINED = 3,035 SQUARE FEET.
3. SEE THE CITY OF EUGENE STORMWATER MANAGEMENT MANUAL FOR ADDITIONAL
INFORMATION.
4. FILTER FABRIC MUST BE ONE OF THE FOLLOWING TYPES/BRANDS: LINQ 125EX; LINQ
TYPAR3201; TNS E040; TNS R035; TNS R040; TNS R042; AMOCO 4535; MARAFI 140NL OR
APPROVED EQUAL.
5. DRAINAGE ROCK SHALL BE A MINIMUM 2 1/2" TO 1 1/2" DRAIN ROCK.
6. THE PIPE WITHIN THE TRENCH SHALL EITHER BE PVC D2729 OR HDPE LEACH FIELD PIPE.
7. THE TRENCH BOTTOM IS TO BE INSTALLED LEVEL IN ALL DIRECTIONS.
8. BAR RUN MATERIAL ENCOUNTERED AT APPROXIMATELY 7' DEEP. ENSURE THAT
BOTTOM OF SOAKAGE TRENCH IS AT LEAST 1' INTO BAR RUN MATERIAL.
9. OVERFLOW TO CONNECT TO PUBLIC STORMWATER SYSTEM IN 17TH STREET.
NO SCALE
503 17TH STREET, SPRINGFIELD
SOAKAGE TRENCH DESIGN FOR
DRAIN ROCK WRAPPED IN FILTER FABRIC, NOT BOTTOM
NATIVE SOIL BACKFILL
ORENCO CATCH
BASIN MODEL
SCB1236-6L
6" SOLID PIPE
FINISH GRADE
6" SOLID PIPE6" PERFORATED PIPE
LENGTH = 40'
WIDTH = 8'6'2'4" DIA. OPEN
GRATE/CLEANOUT
OVERFLOW PER
NOTE #9
6" SOLID PIPE
DATE: 8/1/24
503 17TH STREET
SOAKAGE TRENCH DETAIL FAVREAU ENGINEERING
SCALE = N.T.S.
E
RIC J. F A V R E A US
E
P. 12 , 2 0 1 7OREGONREGISTERED PROFES
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I
ONALE N G I N EER
TL: 17-03-36-24-03300
Stormwater Management Manual 4-33 Eugene 2014
4.5.14 Soakage Trench O & M Plan
Soakage Trenches are infiltrating flood control devices. Soakage Trenches are linear excavations backfilled with sand and gravel injecting stormwater runoff into the ground recharging groundwater. There are various components within the system – inlet piping, aggregate storage basin and perforated piping. The trench surface may be covered with grating, stone, sand, or a grassed cover with a surface inlet and may also be installed under hard surfaces such as driveways. All facility components, vegetation, and source controls shall be inspected for proper operations and structural stability. These inspections shall occur, at a minimum, quarterly for the first two years from the date of installation, then two times per year afterwards, or within 48 hours after each major storm.
Training and/or Written Guidance information for operating and maintaining Soakage Trenches shall be provided to all property owners and tenants. A copy of the O & M Plan shall be provided to all property owners and tenants.
Inspection Logs shall be kept by the facility owner demonstrating the following items have been inspected and are being maintained properly:
• Access to the Soakage Trench shall be safe and efficient. Obstacles preventing maintenance personnel and/or equipment access to the components of the facility shall be removed.
• Algae Growth located on top of the soakage trench should be removed and disposed of properly.
• Debris/Sediment that is found to clog the pipe shall be removed and disposed of in accordance with applicable federal and state requirements.
• Failing Soakage Trenches shall be repaired and/or replaced if water is noticed on top of trench within 48 hours of a major storm.
• Piping shall be cleared of sediment and debris to maintain conveyance. If piping is clear of sediment and debris and yet conveyance is poorly maintained, fabric around the pipe shall need replacing.
• Shut-Off Valve or Flow-Blocking Mechanism may have been required with the construction of the drywell to temporarily prevent stormwater from flowing into it, in the event of an accidental toxic material spill. This may also involve mats kept on-site that can be used to cover inlet drains in parking lots. The shut-off valve shall remain in good working order, or if mats or other flow-blocking mechanisms are used, they shall be kept in stock on-site.
• Sediment in the aggregate obstructing storage and infiltration shall be excavated and replaced.
• Vegetation such as trees should not be located in or around the soakage trench because roots from trees can penetrate the unit body, and leaves from deciduous
Stormwater Management Manual 4-34 Eugene 2014
trees and shrubs can increase the risk of clogging the intake pipe. Large shrubs or trees that are likely to interfere with operation will be identified at each inspection and removed.
Spill Prevention Measures shall be exercised on site when handling substances that contaminate stormwater. Releases of pollutants shall be corrected as soon as identified.
Non-Chemical Pest Control measures shall be taken to prevent development of insects, mosquitoes, and rodents.