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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 S 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.