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HomeMy WebLinkAboutBLD1998-00669 Stormwater Management Plan :st:" Clark Land Office PLLC ENGINEERING -lc:,:tilj.7: P.O. Box 2199 • 935 North Fifth Avenue LAND SURVEYING Sequim, WA 98382 WETLAND DELINEATION v (360) 681 2161 • Fax (360) 683-5310 DEVELOPMENT CONSULTING �`; Toll Free (888) 681-2161 November 1998 • Drainage Plan for PURCELL/MEIJER CABIN Prepared for: Discovery Bay Construction M.fl F o�wAS �� ow- • �`�FcrsTER�°� w 1/-3 - R' 01E3018-PRCLREP-110398 ZONAL t' EXPIRES 8-25-99 Drainage Plan for PURCELL/MEIJER CABIN II ABSTRACT Kevin Purcell and Lucia Meijer will be constructing a cabin on a 6 acre parcel on Marrowstone Island overlooking the north end of Kilisut Harbor from the top of a high bluff. It is desired to avoid changing the exist- ing drainage patterns as much as possible and especially, to prevent any point discharges of stormwater runoff from reaching the bluff. It is recommended that runoff from the narrow access driveway be diverted back into the very dense vegetation at regular intervals in a manner used successfully elsewhere in Jefferson County to prevent the formation of concentrated runoff. The upper few feet of soil in the area is dense and fairly impermeable. Deeper soils are clean and free draining. Roof run- off is to be directed into a deep, narrow infiltration trench. The trench is designed with provisions to release runoff in a dispensed man- ner in the event that the infiltration trench does not function as in- tended. iii Drainage Plan for PURCELL/MEIJER CABIN CONTENTS I. PROJECT OVERVIEW 1 A. SCOPE 1 B. PROJECT DATA 2 C. EXISTING SITE CONDITIONS 2 1. Topography 3 2. Vegetation 3 3. Drainage 4 4. Soils 4 5. Rainfall 6 6. Time of Concentration 6 II. STORMWATER RUNOFF FROM ROOF 6 III. DISPERSION OF DRIVEWAY RUNOFF 8 IV. REFERENCES 9 V. APPENDIX I - INFILTRATION CALCULATIONS 10 iv ., p I Drainage Plan for PURC'p•TJVMEIJER CABIN I I 1 I. PROJECT JE T OVERVIEW This project consists of the construction of a cabin, including a narrow access driveway, on an existing 6 acre parcel. The land is presently covered with second growth - I -- . `,. _ 4- s . timber and extremely dense t • brush. The building site -n: ,,. t� •• has been cleared and a - narrow access driveway * ; - ,Pr • constructed. There has • been minimal disturbance .-. • -s :, of the natural ve etation. +*�' �' g Photo 1 shows a view from the building site. A. SCOPE Due to the proximity to salt water, mitigation of the quantity of stormwater runoff is Photo 1 not of concern. This drainage plan was pre- pared with the goal of reducing or eliminating sources of point discharge that could cause accelerated erosion of the high bluff. Potential concentrated runoff from the driveway will be dispersed into the existing extremely dense vegetation where it will be allowed to sheet flow in its existing drainage pattern. Roof runoff will be directed into an infiltration trench. To ensure that protection is adequate even if additional impervious surfaces are created in the future, this plan provides a simple method for infiltration facilities to be sized, based on the size of impervious surfaces, at the time of construction of the improvements. 1 Ir B. PROJECT DATA Primary contact for Stormwater issues: David Hanna, PE Owners: Kevin Purcell Lucia Meijer Engineer: David Hanna, PE Clark Land Office 935 N. 5th Avenue Post Office Box 2199 Sequim, WA 98382 (360) 681-2161 (360) 638-5310 (fax) I Contractor: Rob Gruye Discovery Bay Construction Post Office Box 1410 Port Townsend, WA 98368 (360) 385-4372 (360) 385-9697 (fax) Architect: Victoria Carter 1 2618 Eastlake Avenue East Seattle, WA 98102 (206) 322-2065 (206) 328-2981 (fax) Location: The parcel is located near the southwest corner of Fort Flagler State Park on Mar- rowstone Island in the southeast quarter of the southeast quarter of Section 18, Township 30 North, Range 1 East, W. M. , in unincorporated Jefferson County. It over- looks Kilisut Harbor on the west and fronts on Reef Road, a private road, on the east. (See map at beginning of report) Stormwater Mitigat'n: Infiltration and dispersion Receiving Waters: Kilisut Harbor C. EXISTING SITE CONDITIONS The following site conditions represent existing conditions. 2 1. Topography The site is at the top of a high bank overlooking Kilisut Harbor. The ground landward of the bluff slopes gently toward the Harbor. �r a Photo 2 The eastern half of the parcel is nearly flat with a slight slope to the south and west. Photo 2 shows the area between the building site and the bluff. The building site is back in the trees to the left of the photo. 11 2. Vegetation ,t.a - I • I Photo 3 Other than the bluff and breathtaking view, the most striking fea- ture of this parcel is the extraordinarily dense brush. Photo 3 shows this brush just below the building site. This brush is a mix of many tough, woody, drought resistant species, most of them pos- sessing some type of thorns. The density of this brush is being 1 3 I relied on to provide dispersion of stormwater runoff from the driveway. The brush on the site above the building site is even more dense than that below. Second growth timber, salal, and similar species are added to the rose hips and other thorn bushes to create a truly remarkable and nearly impassable vegetative cover. Photo 4 shows an area „. just above the build- ing site where a break has been cleared in the vegetation. The brush appears to be reclaiming the area with a vengeance. Since the dense vege- tation is being relied on to disperse runoff '" --- from the driveway, l,w every effort should be '.� ; . �`, made to minimize its Photo 4 disturbance. Areas disturbed during con- struction can be ex- pected to naturally revegetate in one good growing season. Dis- turbed areas along the driveway and in the vicinity of the well can be expected to heal in this manner. lj 3. Drainage Drainage from the site is primarily sheet flow. There are no eas- ily discernable drainage courses on the site although intermittent drainage courses may form through the brush in various parts of the parcel. The private road along the top of the parcel on the east side intercepts any runoff that may come from the east. The upper soils on this site are quite impermeable with only the top foot or so being capable of receiving significant amounts of in- filtration. After this top foot is saturated, any further rainfall will sheet flow down the slope and over the bluff. The intent of this drainage plan is to mimic this natural action as much as pos- t sible, with only roof runoff being infiltrated below the impervi- ous soils. 4. Soils . The site may be found on map number 43 of the Soil Survey of Jef- ferson County Area (McCreary 1975) . Map number 43 predicts that the soils on this site are type HuC, which is a Hoypus soil. Hoy- pus soils are generally gravelly, clean and free draining. This is an accurate characterization of the deeper soils but not of the surface soils on this site. Sinclair (1994) offers a better de- scription of the underlying geology of this portion of Marrowstone Island. 4 Sinclair describes a cap of nearly impermeable Vashon till over clean, free draining, Vashon advance outwash. Cross Section F-F' on Plate 4 of Sinclair (1994) shows a geologic section that goes through the center of this parcel. -Kw G • Photo 5 Photo 5 shows a soil profile exposed during the excavation for the basement of the cabin. Of particular note is the shallow depth of the roots, about a foot or so below the surface. The lighter band of soil above the head of the ice ax is Vashon till. The darker soils above the lighter band, including the soils among the roots, were formed by weathering of the same Vashon till. These soils are quite dense, hard, and impermeable. The lower soils, beginning just above the head of the ice axe, are clean, free draining Vashon advance outwash sands. c " - ,. Photo 6 Photo 6, taken on the other side of the basement excavation, shows a similar profile, with shallow roots, weathered till, and advance 5 outwash sands. Below these layers, beginning just above the head of the ice ax, is a large lens of clean sandy gravel. While its appearance is strikingly different from that of the advance out- wash sands above, the gravel is also an advance outwash soil and will have essentially the same infiltration characteristics as the overlying advance outwash sands. In summary, the overlying soils are quite hard and impervious to a depth of between 3 and 5 feet in the immediate vicinity of the building site. The advance outwash soils can be expected to infil- trate rain water at a rate between 6 and 20 inches per hour or even more. 5. Rainfall The total amount of precipitation falling over a 24 hour period during a storm having a mean recurrence interval of 25 years, will be 2.0 inches. PROJECT LOCATION This informa- tion was taken } from a 25 �oN 1 year, 24 hour r ' Isopluvial Map 29^, — published by the U.S. Soil t = Conservation I t . Service (SCS � l � ;. i 1982) , a por- � � tion of which 26N 1 d � V '� , �1 is reproduced I I l l ° as Figure 1. TOW 9✓Y SW 7N 6W 5W 4N j',y 2W 11,,E 25 year rain- ISOPLUVIALS OF 25-YEAR 24-HOUR fall data is PRECIPITATION IN TENTHS OF AN INCH used for de- sign purposes. Figure 1 The rainfall distribution is assumed to be a Type IA distribution per standard practice in the area. 6. Time of Concentration As an additional conservative measure, actual instantaneous rain- fall was used to size the infiltration trench rather than calcu- lated runoff, which could be as little as half of the rainfall. For this reason, the Time of Concentration was not needed to cal- culate runoff. II. STORMWATER RUNOFF FROM ROOF This plan uses a hydrograph based method of calculating runoff known as the Santa Barbara Urban Hydrograph Method. Rainfall hyetographs taken from the King County Surface Water Design Manual, (King County Public Works Department 1995) , were used along with rainfall data for the Mar- rowstone Island area to calculate the rainfall distribution. This rain- fall distribution was then routed onto the roof and into the infiltra- tion system using the Santa Barbara Urban Hydrograph Method to determine hydrographs for infiltration. This method is specifically accepted by 6 • Section III-1.3 of the Stormwater Management Manual for the Puget Sound Basin (The Technical Manual) (Birch 1992) . This method yields runoff volumes that are different from those deter- mined using the rational method. While the rational method is excellent for conservatively sizing channels and conduits for small watersheds, it does not adequately consider the time element of runoff that is neces- sary in calculating runoff hydrographs. Infiltration calculations are included in Appendix I in the order dis- cussed below. These calculations are based on runoff from 1,000 square feet of roof area. • A Summary of Stormwater Infiltration System Operational Characteris- tics provides pertinent results in a concise format. The results of the 25 year storm are used for design purposes. • Calculation of a Rainfall hyetograph for the 25 year design storm are included next. These are simply a mapping of the design storm's in- tensity at 10 minute intervals throughout the 24 hour period. • The Infiltration System Staging Table shows various properties of the infiltration system as a function of the height of the water level in the system. • The 25 Year, 24 Hour Flood Routing calculations show flow into and out of (via infiltration) the system as well as the amount of water stored and various other properties of interest as a function of time during the 24 hour design period. These calculations show that the system will handle flows from 1,000 square feet of roof area during a 25 year, 24 hour design event. The soils in the vicinity of this project are not particularly perme- able. Additional stormwater runoff from relatively small, isolated im- provements such as individual graveled driveways, small (less than 100 square feet) outbuildings, and similar improvements can be expected to soak into the ground, but only after some time. Due to the larger lot size, such items need not be provided with infiltration facilities. Runoff from larger improvements such as the home, garage and the like should be directly infiltrated into the ground as provided for in this drainage plan. It should be noted that infiltration of stormwater above a high bluff is often not a recommended solution. In this instance, the choice is be- tween allowing concentrated runoff from the roof to flow directly over the bluff or infiltrating it into clean soils below the cap of imperme- able till, where it will eventually seep out of the face of the bluff. Due to the small area of roof to be drained and the distance from the face of the bluff, the additional seepage that will eventually occur through the face of the bluff will be very minor. To ensure that the im- pact of infiltrating roof runoff is not increased, great care should be taken that surface water is not allowed to enter the infiltration sys- tem, either by entering at the base of the roof drains or by being al- lowed to flow into the top of the infiltration trench. The infiltration trench is designed to function as a flow dispersion fa- cility in the event that it becomes clogged or is simply overloaded by a storm greater than the design storm. In such cases, extra flows will 7 seep out of the top of the trench in sheet flows, eventually flowing over the top of the bluff in the same manner that they do at present. This plan provides for the use of infiltration facilities to infiltrate runoff from roof drains. These facilities must be sized using the meth- ods given in the construction plans and specifications included as Ap- pendix III. Permission is hereby granted to copy the plans and specifi- cations for roof drain infiltration systems for the sole use of this lot. a , � ' '-` _.ti The formulas shown in the construc- ; , s tion plans for sizing infiltration ;`' facilities are derived using site . ° N specific rainfall and soils infor- tL. •`� ` • 110r •a, •- mation and will not apply to other • 5+1`•;i_ projects, even those that may be ;%/1111•: s* . .,1 x .. nearby. F {,tt, c i fi t1 ° ' f III. DISPERSION OF DRIVEWAY RUNOFF *'' R As shown in Photo 7, final con- 4 -r, struction of the driveway has not Fl . . been completed, but all clearing has been accomplished. Normal, continuous roadside drain- age ditches should not be con- structed along the driveway. In- stead, short ditch sections, each less than 100 feet in length, should be constructed with diver- sions at the bottom of each to di- vert flows off into the brush. Cross culverts should be installed I Photo 7 as needed to allow water that accu- mulates in ditch sections above the road to cross the road and be dispersed out of one of the diversion ditches. 8 The diversion ditches should be constructed only to the edge of the vegeta- - tion unless additional length is required to avoid • - ponding. The goal is to take potentially concen- trated runoff from the driveway and allow it to spread out as sheet flow as Y - soon as possible. = ;; Photo 8 shows a typical �^� flow dispersion ditch con- : , ;�., structed on another project western Jefferson � -:.-Z-141044. County. The ditch section terminates just to the right of the photo, allow- , ing flows to be spread out in the vegetation. Photo 8 IV. REFERENCES Birch, Peter B. , Pressley, Helen E. , Hartigan, Patrick D. , 1992, Storm- water Management Manual For The Puget Sound Basin, The Technical Manual: Washington State Department of Ecology King County Public Works Department, 1995, King County Surface Water De- sign Manual: King County Public Works Department. McCreary, Fred R. , 1975, Soil Survey of Jefferson County Area, Washing- ton: United States Department of Agriculture, Soil Conservation Service. Sinclair, Kirk A. ; Garrigues, Robert S. , 1994, Geology, Water Resources, and Seawater Intrusion Assessment of Marrowstone Island, Jefferson County, Washington: Washington Department of Ecology, Water Supply Bulletin No. 59. 9 V. APPENDIX I - INFILTRATION CALCULATIONS I I I I I 1 10 I a o PROJECT: Purcell/Meijer Cabin Date: 11-3-98 SUMMARY OF STORMWATER MITIGATION SYSTEM OPERATIONAL CHARACTERISTICS Mitigation: Infiltration Trench, 25 feet long 1.00 feet wide 5.00 feet of drain rock in bottom, 4.6 cu yd of drain rock required PROJECT: Purcell/Meijer Cabin Date: 11-3-98 SUMMARY OF STORMWATER MITIGATION SYSTEM OPERATIONAL CHARACTERISTICS Mitigation: Infiltration Trench, 25 feet long 1.00 feet wide 5.00 feet of drain rock in bottom, 4.6 cu yd of drain rock required RAINFALL DATA 24 hr rainfall depth Peak Rainfall Intensity 25 yr storm: 2 (in) 0.0150 (cfs) INFILTRATION DATA Infiltration Rate (inches/hour) . . 5 Void Ratio of Rock 0.3 ==> 30% voids/70% rock Sidewall Infilt'n Coefficient. . . 0.01 ==> 0.05 in/hr MISCELLANEOUS PARAMETERS Duration of Design Storm: 24 (hr) Staging Table Starting Depth: 0 (ft) Staging Table Depth Increment: 0.05 (ft) Maximum Depth of Staging Table: 10 (ft) Time Increment, dT = 10 minutes = 600 (sec) Flood Routing Input Data Taken From Rainfall Hydrograph 25 YEAR STORM ROUTING DATA Peak Inflow Rate: 0.0150 (cfs) Peak Outflow Rate: 0.0031 (cfs) Peak Infiltration Rate: 0.0031 (cfs) Peak Outflow Rate via Flow Controls: 0.0000 (cfs) Maximum Allowable Outflow Rate via Controls: 0.0028 (cfs) Peak Water Depth: 2.7108 (feet) Peak Water Surface Elevation: 102.7108 (feet) A PROJECT: Purcell/Meijer Cabin 25 yr storm (B) Total Basin Area = 1002 sq ft = 0. 0230 Ac Storm Duration = 24 hr Peak Rainfall Intensity = 0. 015 cfs Total Rainfall Volume = 167 cu ft Total, 24 hr rainfall = 2. 00 in Rainfall Data Standard SCS Type IA 24 hr hyetograph (adj 'd) Total Cumulative from King Co Drn Manual Basin Precip Precip Rainfall Depth Depth Time % Cumulative Time P Pr Prc (min) Precip % Precip (hrs) (cfs) (in) (in) 0 0.00 0.00 0.00 0.0000 0. 0000 0.0000 10 0.40 0.40 0.17 0. 0011 0.0080 0.0080 20 0.40 0. 80 0.33 0.0011 0. 0080 0.0160 30 0.40 1.20 0.50 0.0011 0.0080 0.0240 40 0.40 1. 60 0. 67 0.0011 0. 0080 0. 0320 50 0.40 2.00 0. 83 0.0011 0.0080 0.0400 60 0.40 2.40 1. 00 0.0011 0.0080 0.0480 70 0.40 2.80 1.17 0.0011 0.0080 0.0560 80 0.40 3.20 1.33 0.0011 0.0080 0.0640 90 0.40 3.60 1.50 0.0011 0.0080 0.0720 ' 100 0.40 4.00 1.67 0.0011 0.0080 0.0800 110 0.50 4.50 1.83 0.0014 0.0100 0.0900 120 0.50 5.00 2.00 0.0014 0.0100 0.1000 130 0.50 5.50 2.17 0. 0014 0.0100 0.1100 140 0.50 6.00 2.33 0.0014 0.0100 0.1200 150 0.50 6.50 2.50 0.0014 0.0100 0.1300 160 0.50 7.00 2. 67 0.0014 0.0100 0.1400 170 0. 60 7.60 2.83 0.0017 0.0120 0.1520 180 0. 60 8.20 3.00 0.0017 0.0120 0.1640 190 0. 60 8.80 3. 17 0.0017 0.0120 0. 1760 200 0. 60 9.40 3.33 0.0017 0.0120 0.1880 210 0. 60 10. 00 3.50 0.0017 0.0120 0.2000 220 0. 60 10. 60 3. 67 0.0017 0. 0120 0.2120 I 230 0.70 11.30 12.00 3.83 0.0019 0.0140 0.2260 240 0.70 4.00 0.0019 0. 0140 0.2400 250 0.70 12.70 4. 17 0.0019 0.0140 0.2540 260 0.70 13.40 4.33 0.0019 0.0140 0.2680 270 0.70 14. 10 4.50 0. 0019 0.0140 0.2820 280 0.70 14.80 4. 67 0. 0019 0.0140 0.2960 290 0.82 15.62 4. 83 0.0023 0.0164 0.3124 300 0. 82 16.44 5. 00 0.0023 0.0164 0. 3288 310 0. 82 17.26 5. 17 0. 0023 0.0164 0. 3452 320 0. 82 18. 08 5.33 0.0023 0.0164 0.3616 330 0. 82 18.90 5.50 0.0023 0.0164 0.3780 340 0. 82 19.72 5. 67 0.0023 0.0164 0.3944 350 0. 95 20. 67 5.83 0.0026 0.0190 0.4134 360 0. 95 21.62 6.00 0.0026 0.0190 0.4324 370 0. 95 22.57 6.17 0.0026 0.0190 0.4514 380 0.95 23.52 6.33 0.0026 0.0190 0.4704 PROJECT: Purcell/Meijer Cabin 25 yr storm (B) Total Basin Area = 1002 sq ft = 0.0230 Ac Storm Duration = 24 hr Peak Rainfall Intensity = 0. 015 cfs Total Rainfall Volume = 167 cu ft Total, 24 hr rainfall = 2.00 in Rainfall Data Standard SCS Type LA 24 hr hyetograph (adj 'd) Total Cumulative from King Co Drn Manual Basin Precip Precip Rainfall Depth Depth Time % Cumulative Time P Pr Prc (min) Precip % Precip (hrs) (cfs) (in) (in) t' 390 0.95 24.47 6.50 0. 0026 0.0190 0.4894 ;f 400 0.95 25.42 6. 67 0.0026 0. 0190 0.5084 410 1.33 26.75 6. 83 0.0037 0. 0266 0.5350 420 1.33 28.08 7. 00 0.0037 0.0266 0.5616 430 1.33 29.41 7. 17 0. 0037 0.0266 0.5882 440 1.80 31.21 7.33 0.0050 0.0360 0. 6242 450 1.80 33.01 7.50 0.0050 0.0360 0. 6602 460 3.40 36.41 7. 67 0.0095 0.0680 0.7282 470 5.40 41.81 7.83 0.0150 0.1080 0. 8362 480 2.70 44.51 8. 00 0.0075 0.0540 0.8902 11 490 1.80 46.31 8.17 0.0050 0.0360 0.9262 500 1.34 47.65 8.33 0.0037 0.0268 0.9530 510 1.34 48.99 8.50 0.0037 0.0268 0.9798 520 1.34 50.33 8. 67 0. 0037 0.0268 1. 0066 530 0.88 51.21 8. 83 0. 0024 0.0176 1.0242 540 0.88 52.09 9. 00 0.0024 0.0176 1. 0418 550 0.88 52.97 9. 17 0.0024 0.0176 1.0594 560 0.88 53.85 9.33 0.0024 0.0176 1.0770 570 0.88 54.73 9.50 0.0024 0.0176 1.0946 580 0.88 55.61 9. 67 0.0024 0.0176 1. 1122 0 590 0.88 56.49 57.37 9. 83 0.0024 0.0176 1. 1298 600 0. 88 10. 00 0.0024 0.0176 1. 1474 610 0.88 58.25 10. 17 0.0024 0.0176 1. 1650 620 0.88 59.13 10.33 0.0024 0.0176 1. 1826 630 0. 88 60.01 10.50 0.0024 0.0176 1.2002 640 0.88 60. 89 10. 67 0.0024 0.0176 1.2178 650 0.72 61.61 10. 83 0.0020 0.0144 1.2322 I660 0.72 62.33 11. 00 0.0020 0.0144 1.2466 670 0.72 63.05 11. 17 0. 0020 0.0144 1.2610 680 0.72 63.77 11.33 0. 0020 0.0144 1.2754 I 690 0.72 64.49 65.21 11.50 0. 0020 0.0144 1.2898 700 0.72 11. 67 0.0020 0.0144 1.3042 710 0.72 65.93 11. 83 0. 0020 0.0144 1.3186 720 0.72 66.65 12. 00 0. 0020 0.0144 1.3330 730 0.72 67.37 12. 17 0. 0020 0.0144 1.3474 740 0.72 68.09 12.33 0.0020 0.0144 1.3618 750 0.72 68.81 12.50 0.0020 0.0144 1. 3762 760 0.72 69.53 12. 67 0. 0020 0.0144 1.3906 770 0.57 70.10 12. 83 0.0016 0.0114 1.4020 PROJECT: Purcell/Meijer Cabin 25 yr storm (B) Total Basin Area = 1002 sq ft = 0. 0230 Ac Storm Duration = 24 hr Peak Rainfall Intensity = 0.015 cfs Total Rainfall Volume = 167 cu ft Total, 24 hr rainfall = 2.00 in Rainfall Data Standard SCS Type lA 24 hr hyetograph (adj 'd) Total Cumulative from King Co Drn Manual Basin Precip Precip Rainfall Depth Depth Time % Cumulative Time P Pr Prc (min) Precip % Precip (hrs) (cfs) (in) (in) 780 0.57 70.67 13.00 0.0016 0.0114 1.4134 790 0.57 71.24 13.17 0.0016 0.0114 1.4248 800 0.57 71. 81 13.33 0.0016 0.0114 1.4362 810 0.57 72.38 13.50 0.0016 0.0114 1.4476 820 0.57 72.95 13.67 0.0016 0.0114 1.4590 830 0.57 73.52 13.83 0.0016 0.0114 1.4704 840 0.57 74.09 14.00 0.0016 0.0114 1.4818 850 0.57 74.66 14.17 0.0016 0.0114 1.4932 860 0.57 75.23 14.33 0.0016 0.0114 1.5046 870 0.57 75.80 14.50 0.0016 0.0114 1.5160 880 0.57 76.37 14.67 0.0016 0.0114 1.5274 890 0.50 76.87 14. 83 0.0014 0.0100 1.5374 900 0.50 77.37 15.00 0.0014 0.0100 1.5474 910 0.50 77.87 15.17 0.0014 0.0100 1.5574 920 0.50 78.37 15.33 0.0014 0.0100 1.5674 930 0.50 78.87 15.50 0.0014 0.0100 1.5774 940 0.50 79.37 15.67 0.0014 0.0100 1.5874 950 0.50 79. 87 15. 83 0.0014 0.0100 1.5974 960 0.50 80.37 16.00 0.0014 0.0100 1.6074 970 0.50 80. 87 16. 17 0.0014 0.0100 1.6174 980 0.50 81.37 16.33 0.0014 0.0100 1. 6274 990 0.50 81. 87 16.50 0.0014 0.0100 1.6374 1000 0.50 82.37 16.67 0.0014 0.0100 1.6474 1010 0. 43 82.80 16.83 0.0012 0.0086 1.6560 1020 0.40 83.20 17.00 0.0011 0.0080 1.6640 1030 0.40 83.60 17.17 0.0011 0.0080 1.6720 1040 0.40 84.00 17.33 0.0011 0.0080 1.6800 1050 0.40 84.40 17.50 0.0011 0.0080 1.6880 1060 0.40 84.80 17.67 0. 0011 0.0080 1. 6960 1070 0.40 85.20 17. 83 0.0011 0.0080 1.7040 1080 0.40 85.60 18. 00 0.0011 0.0080 1.7120 1090 0. 40 86. 00 18. 17 0.0011 0.0080 1.7200 1100 0.40 86.40 18.33 0.0011 0. 0080 1.7280 1110 0.40 86. 80 18.50 0.0011 0. 0080 1.7360 1120 0.40 87.20 18. 67 0.0011 0.0080 1.7440 1130 0.40 87.60 18. 83 0.0011 0.0080 1.7520 1140 0.40 88.00 19.00 0.0011 0.0080 1.7600 1150 0.40 88.40 19. 17 0. 0011 0.0080 1.7680 1160 0.40 88.80 19.33 0.0011 0.0080 1.7760 PROJECT: Purcell/Meijer Cabin C°; 25 yr storm (B) Total Basin Area = 1002 sq ft = 0. 0230 Ac Storm Duration = 24 hr Peak Rainfall Intensity = 0. 015 cfs Total Rainfall Volume = 167 cu ft Total, 24 hr rainfall = 2.00 in Rainfall Data Standa rd d SCS Type 1A 24 hr hyetograph (adj 'd) Total Cumulative from King Co Drn Manual Basin Precip Precip Rainfall Depth Depth Time % Cumulative Time P Pr Prc (min) Precip % Precip (hrs) (cfs) (in) (in) 1170 0.40 89.20 19.50 0.0011 0.0080 1.7840 1' 1180 0.40 89. 60 19. 67 0.0011 0.0080 1.7920 1190 0.40 90.00 19. 83 0. 0011 0.0080 1.8000 1200 0.40 90.40 20.00 0. 0011 0.0080 1. 8080 1210 0.40 90. 80 20. 17 0.0011 0.0080 1. 8160 1220 0.40 91.20 20.33 0.0011 0. 0080 1. 8240 1230 0.40 91.60 20.50 0. 0011 0.0080 1. 8320 I 1240 0.40 92. 00 20. 67 0.0011 0.0080 1.8400 1250 0.40 92.40 20.83 0.0011 0.0080 1.8480 1260 0.40 92.80 21.00 0.0011 0.0080 1.8560 1270 0.40 93.20 21.17 0.0011 0.0080 1.8640 1280 0.40 93.60 21.33 0. 0011 0.0080 1.8720 1290 0.40 94.00 21.50 0.0011 0.0080 1. 8800 1300 0.40 94.40 21.67 0.0011 0.0080 1.8880 I 1310 0.40 94.80 21. 83 0.0011 0.0080 1.8960 1320 0.40 95.20 22. 00 0. 0011 0.0080 1. 9040 1330 0.40 95.60 22.17 0. 0011 0.0080 1. 9120 I 1340 0.40 96.00 22.33 0.0011 0.0080 1. 9200 1350 0.40 96.40 22.50 0. 0011 0. 0080 1.9280 1360 0.40 96.80 22.67 0.0011 0.0080 1. 9360 1370 0.40 97.20 22.83 0.0011 0. 0080 1. 9440 1380 0.40 97. 60 23. 00 0. 0011 0.0080 1. 9520 1390 0. 40 98.00 23. 17 0.0011 0.0080 1.9600 1400 0.40 98.40 23.33 0. 0011 0.0080 1. 9680 1410 0.40 98.80 23.50 0.0011 0.0080 1. 9760 1420 0.40 99.20 23. 67 0.0011 0.0080 1. 9840 1430 0.40 99. 60 23. 83 0.0011 0.0080 1. 9920 1440 0.40 100.00 24.00 0.0011 0.0080 2.0000 1450 0.00 100.00 24. 17 0.0000 0.0000 2. 0000 1460 0.00 100. 00 24.33 0. 0000 0.0000 2.0000 1470 0.00 100.00 24.50 0.0000 0.0000 2. 0000 1480 0. 00 100.00 24 . 67 0.0000 0.0000 2.0000 1490 0.00 100.00 24. 83 0. 0000 0.0000 2.0000 1500 0.00 100. 00 25. 00 0.0000 0.0000 2. 0000 100.00 2.0000 Purcell/Meijer Cabin Infiltration System Staging Table Water Outflow Surface via Total Staging Depth WS Elev Volume Area Infilt'n Outflow Coef't (feet) (feet) (cu ft) (sq ft) (cfs) (cfs) a D WS V A Q6 Qtot 0.00 0.00 100. 00 0 0 0.000 0.00 0.05 100. 05 0. 000 0 25 0.003 0. 003 0.01 0.10 100. 10 1 25 0. 003 0. 003 0.01 0.15 100. 15 1 25 0. 003 0.003 0.01 0.20 100.20 2 25 0.01 0.25 100.25 0. 003 0. 003 2 25 0. 003 0.003 0.01 0.30 100.30 2 25 0.01 0.35 100.35 0. 003 0.003 3 25 0. 003 0.003 0.01 0.40 100.40 3 25 0.003 0.01 0.45 100.45 0.003 3 25 0. 003 0. 003 0. 02 0.50 100.50 4 25 0. 003 0. 02 0.55 100.55 0.003 4 25 0.003 0.003 0.02 0. 60 100. 60 5 25 0. 003 0.003 0. 02 0.65 100.65 5 25 0.003 0. 02 0.70 100.70 0.003 5 25 0.003 0.003 0.02 0.75' 100.75 6 25 0.003 0.003 0.02 0.80 100. 80 6 25 0.003 0. 003 0.02 0.85 100.85 6 25 0.003 0.03 0.90 0. 003 100. 90 7 25 0.003 0.003 0.03 0.95 100. 95 7 25 0. 003 0.003 0.03 1.00 101.00 8 25 0.003 0.003 0.03 1.05 101.05 8 25 0.003 0.03 1.10 0.003 101. 10 8 25 0. 003 0.003 0.03 1.15 101. 15 9 25 0. 003 0.003 0.03 1.20 101.20 9 25 0.003 0.003 0.03 1.25 101.25 9 25 0. 003 0.04 1.30 0.003 101.30 10 25 0. 003 0.003 0.04 1.35 101. 35 10 25 0. 003 0.04 1.40 0. 003 101.40 11 25 0. 003 0.003 0. 04 1.45 101.45 11 25 0. 003 0. 04 1.50 101.50 0.003 11 25 0.003 0.003 0.04 1.55 101.55 12 25 0.003 0.04 1.60 101.60 0.003 12 25 0. 003 0.003 0. 04 1. 65 101. 65 12 25 0. 003 0.003 0. 05 1.70 101.70 13 25 0.003 0.003 0. 05 1.75 101.75 13 25 0.003 0.05 1.80 0.003 101. 80 14 25 0.003 0.003 0.05 1.85 101. 85 14 25 0. 003 0.003 0.05 1.90 101. 90 14 25 0. 003 0.003 0. 05 1. 95 101. 95 15 25 0.003 0.003 0.05 2.00 102. 00 15 25 0.003 0.003 0.05 2.05 102.05 15 25 0.003 0.003 0.06 2.10 102.10 16 25 0. 003 0.003 0.06 2.15 102.15 16 25 0.003 0.06 2.20 102.20 17 0.003 25 0.003 0.003 Purcell/Meijer Cabin II Infiltration System Staging Table IIWater Outflow Surface via Total Staging Depth WS Elev Volume Area Infilt'n Outflow Coef't (feet) (feet) (cu ft) (sq ft) (cfs) (cfs) a D WS V A Q6 Qtot I0.06 2.25 102.25 17 25 0. 003 0.003 0.06 2.30 102.30 17 25 0.003 0.003 0.06 2.35 102.35 18 25 0.003 0.003 I 0.06 2.40 102.40 18 25 0. 003 0. 003 0.06 2.45 102.45 18 25 0.003 0.003 0.07 2.50 102.50 19 25 0. 003 0.003 0.07 2.55 102.55 19 25 0.003 0.003 0.07 2. 60 102.60 19 25 0.003 0.003 0.07 2. 65 102.65 20 25 0.003 0.003 0. 07 2.70 102.70 20 25 0.003 0. 003 I 0.07 2.75 102.75 21 25 0.003 0.003 0.07 2. 80 102.80 21 25 0.003 0.003 0.07 2. 85 102.85 21 25 0.003 0.003 0.08 2.90 102.90 22 25 0.003 0.003 0.08 2.95 102. 95 22 25 0.003 0.003 0.08 3.00 103.00 22 25 0.003 0. 003 I 0.08 3. 05 103.05 23 25 0. 003 0.003 0.08 3. 10 103.10 23 25 0.003 0.003 :. 0.08 3. 15 103.15 24 25 0.003 0.003 0.08 3.20 103.20 24 25 0.003 0. 003 I 0.08 3.25 103.25 24 25 0.003 0.003 0.09 3.30 103.30 25 25 0.003 0.003 0.09 3.35 103.35 25 25 0.003 0.003 I 0.09 3.40 103.40 25 25 0.003 0.003 0.09 3.45 103.45 26 25 0.003 0.003 0.09 3.50 103.50 26 25 0.003 0.003 I 0. 09 3.55 103.55 27 25 0.003 0.003 0.09 3. 60 103. 60 27 25 0. 003 0.003 0.09 3. 65 103.65 27 25 0. 003 0. 003 0.10 3.70 103.70 28 25 0.003 0.003 I 0.10 3.75 103.75 28 25 0.003 0.003 0.10 3.80 103.80 28 25 0.003 0.003 0.10 3.85 103.85 29 25 0.003 0.003 I 0.10 3. 90 103. 90 29 25 0. 003 0.003 0.10 3.95 103.95 30 25 0. 003 0. 003 0.10 4.00 104.00 30 25 0.003 0. 003 1 0.10 4. 05 104. 05 30 25 0.003 0.003 0.11 4. 10 104.10 31 25 0. 003 0.003 0.11 4. 15 104.15 31 25 0.003 0.003 0. 11 4.20 104.20 31 25 0.003 0.003 0.11 4.25 104.25 32 25 0. 003 0.003 0. 11 4.30 104.30 32 25 0.003 0.003 0. 11 4.35 104.35 33 25 0.003 0. 003 0.11 4.40 104.40 33 25 0.003 0.003 0.11 4.45 104.45 33 25 0.003 0. 003 Purcell/Meijer Cabin Infiltration System Staging Table . 3 Water Outflow Surface via Total Staging Depth WS Elev Volume Area Infilt'n Outflow Coef't (feet) (feet) (cu ft) (sq ft) (cfs) (cfs) a D WS V A Q6 Qtot 0. 12 4.50 104.50 34 25 0.003 0. 003 0. 12 4.55 104.55 34 25 0.003 0. 003 0. 12 4.60 104. 60 34 25 0.003 0. 003 0.12 4.65 104. 65 35 25 0.003 0. 003 0.12 4.70 104.70 35 25 0.003 0. 003 0.12 4.75 104.75 36 25 0. 003 0. 003 0.12 4.80 104.80 36 25 0.003 0. 003 0.12 4. 85 104.85 36 25 0.003 0. 003 0.13 4.90 104.90 37 25 0.003 0. 003 0.13 4.95 104.95 37 25 0. 003 0. 003 0.13 5.00 105.00 37 25 0.003 0. 003 • ll '4, -: I ;1; II li F s t Ii 1,1 Ir PROJECT: Purcell/Meijer Cabin 25 YEAR, 24 HOUR FLOOD ROUTING (B) Outflow via Total Time Inflow Infilt'n Outflow Depth Volume Staging (hrs) (cfs) (cfs) (cfs) '_ (feet) (cu ft) Coef't t Qin Q6 Qtot D V a 0.00 0.0000 0.000 0.17 0. 0011 0. 000 0.00 0 �'`''` 0. 001 0. 0 01 0. 01 0. 00 0.33 0.0011 0.001 0 0. 00 0.50 0.0011 0. 001 0.02 0 0.001 0. 001 0. 02 0. 00 0.67 0.0011 0.001 0. 001 0.02 0 0.00 0 0. 00 , 0.83 0.0011 0.001 7 + 1. 00 0.0011 0. 001 0.02 0 0.00 0.001 0. 001 0.02 1.17 0.0011 0. 001 0 0.00 0.001 0.02 0 v' 1.33 0.0011 0.001 0. 001 0.02 0. 00 ,. 1.50 0.0011 0. 001 0.001 0.02 0 0.00 0 0.00 1. 67 0.0011 0.001 0. 001 0.02 1.83 0.0014 0. 001 0 0. 00 �� 2. 00 0. 0014 0.001 0.001 0.02 0 0. 00 0. 001 0. 02 2.17 0.0014 0.001 0. 001 0.02 0 0. 00 2.33 0.0014 0.001 0 0. 00 2.50 0.0014 0.001 0. 02 0 • 0.001 0.001 0.02 0.00 2.67 0.0014 0.001 0.001 0 0. 00 2.83 0.0017 0.002 0.02 0 0. 00 0.002 0.03 0 ,, 3.00 0.0017 0.002 0.002 0.00 3.17 0.0017 0.03 0 0.00 0.002 0.002 0.03 3.33 0.0017 0.002 0 0. 00 3.50 0.0017 0.002 0.03 0 0.002 0.03 0.002 0.00 3.67 0.0017 0.002 0 0..00 3.83 0.0019 0.002 0.03 0 0.002 0. 0020. 00 4. 00 0.0019 0.03 0 0.00 0.002 0.002 0.03 4.17 0.0019 0.002 0.002 0.03 0 0. 00 s 4.33 0. 0019 0.002 0. 002 0.03 0 0.00 4.50 0.0019 0.002 0 0. 00 4 � 4. 67 0. 0019 0. 002 0.03 0 0.002 0. 002 0. 00 4.83 0. 0023 0.03 0 0.00 0.002 0. 002 0.04 ' 5.00 0.0023 0.002 0 0. 00 5. 17 0.0023 0. 002 0. 04 0 0.002 0. 002 0. 00 5.33 0.0023 0.04 0 0. 00 :; 0.002 0.002 0. 04 a ' 5.50 0.0023 0.002 0 0.00 5. 67 0. 0023 0. 002 0.04 0 0.002 0. 002 0. 00 5.83 0. 0026 0. 04 0 0. 00 0.003 0. 003 0. 04 P:: 6.00 0.0026 0 0. 00 i 0.003 0.003 0.05 `_ 6. 17 0.0026 0.003 0. 003 0.05 0 0. 00 6.33 0.0026 0.003 0. 003 0.05 0 0. 00 0 0. 00 6.50 0.0026 0.003 0.003 0.05 6. 67 0.0026 0. 003 0. 003 0.05 0 0.00 { 6. 83 0.0037 0.003 0.003 0.08 0 0. 001 7. 00 0.0037 0.003 0.003 0.14 1 0. 01 1 0.01 7.17 0.0037 0.003 0. 003 0.21 7.33 0.0050 0.003 0.003 0.32 2 0.01 2 0.02 PROJECT: Purcell/Meijer Cabin 25 YEAR, 24 HOUR FLOOD ROUTING (B) i- Outflow via Total Time Inflow Infilt'n Outflow Depth Volume Staging (hrs) (cfs) (cfs) (cfs) (feet) (cu ft) Coef't t Qin Q6 Qtot D V a 7.50 0.0050 0. 003 0. 003 0. 49 4 0.02 7. 67 0. 0095 0.003 0. 003 0.83 6 0.04 7. 83 0. 0150 0.003 0. 003 1.58 12 0.06 8.00 0.0075 0.003 0. 003 2.24 17 0.07 ` 8.17 0.0050 0.003 0. 003 2.49 19 0.07 8.33 0.0037 0.003 0.003 2.60 20 0.07 8.50 0.0037 0.003 0.003 2.65 20 0.07 8.67 0.0037 0.003 0. 003 2.71 20 0.07 8.83 0.0024 0.003 0.003 2.71 20 0.07 9.00 0.0024 0.003 0.003 2. 66 20 0.07 9.17 0.0024 0.003 0.003 2. 61 20 0.07 9.33 0. 0024 0. 003 0.003 2.57 19 0.07 Oikt 9.50 0.0024 0.003 0.003 2.52 19 0.06 9. 67 0.0024 0.003 0.003 2.47 19 0.06 9.83 0.0024 0.003 0.003 2.42 18 0.06 10.00 0.0024 • 0.003 0.003 2.38 18 0.06 _ 10.17 0.0024 0.003 0.003 2.33 17 0.06 4t 10.33 0.0024 0.003 0.003. 2.28 17 0.06 4 10.50 0. 0024 0.003 0.003 2.24 17 0.06 ; 10.67 0. 0024 0.003 0.003 2.19 16 0.06 10.83 0.0020 0.003 0.003 2. 13 16 0.05 5 11.00 0. 0020 0. 003 0.003 2.05 15 0.05 11.17 0.0020 0.003 0.003 1. 96 15 0.05 11.33 0.0020 0.003 0.003 1.88 14 0.05 11.50 0.0020 0. 003 0.003 1. 80 14 0.05 11.67 0.0020 0.003 0.003 1.72 13 . 0.04 11.83 0.0020 0.003 0.003 1. 64 12 0.04 4, 12. 00 0. 0020 0.003 0.003 1.57 12 0.04 z; 12.17 0. 0020 0.003 0.003 1.49 11 0.04 12.33 0.0020 0. 003 0.003 1.41 11 0.04 µ:; 12.50 0.0020 0.003 0. 003 1.33 10 0.03 12. 67 0.0020 0.003 0.003 1.25 9 0.03 12. 83 0.0016 0.003 0. 003 1.16 9 0. 03 t; 13. 00 0.0016 0.003 0. 003 1.05 8 0.03 i. 17 13.17 0.0016 0.003 0.003 0. 94 7 0. 02 13.33 0.0016 0.003 0. 003 0. 83 6 0.02 13.50 0.0016 0.003 0. 003 0.72 5 0.02 13.67 0. 0016 0.003 0. 003 0. 62 5 0.02 13. 83 0. 0016 0.003 0. 003 0. 51 4 0.01 14.00 0. 0016 0.003 0.003 0.40 3 0.01 , 14.17 0. 0016 0.003 0.003 0.30 2 0.01 14.33 0.0016 0.003 0.003 0. 19 1 0.01 14.50 0.0016 0.003 0.003 0.08 1 0.00 14.67 0.0016 0.002 0.002 0.03 0 0.00 14.83 0.0014 0.001 0.001 0.02 0 0.00 • rI PROJECT: Purc ell/Meijer Cabin �. 25 YEAR, 24 HOUR FLOOD ROUTING (B) 1 x - Outflow via Total fa Time Inflow Infilt'n Outflow Depth Volume Staging A (hrs) (cfs) (cfs) (cfs) (feet) (cu ft) Coef't T . Qin Q6 Qtot D V a 15. 00 0.0014 0.001 0.001 0. 02 15.17 0.0014 0. 001 0.001 0.02 0 0. 00 0 0. 00 15.33 0.0014 0. 001 15.50 0.0014 0.001 0.001 0.02 0 0. 00 0.001 0.02 0 0. 00 15. 67 0.0014 0.001 PY- 15.83 0.0014 0. 001 0.02 0 0. 00 0.001 0. 001 0.02 0 16. 00 0. 0014 0.001 0. 001 0. 02 0. 00 i' 16.17 0.0014 0.001 0 0. 00 16.33 0.0014 0.001 0. 001 0. 02 0 0. 00 0. 001 0. 02 0 0. 00 16.50 0.0014 0.001 0. 001 0.02 0 0.00 16. 67 0. 0014 0. 001 0. 001 0.02 0 0.00 16.83 0. 0012 0. 001 0. 001 0.02 0 0.00 17.00 0. 0011 0.001 0. 001 0.02 0 17. 17 0. 0011 0.001 0.001 0.02 0. 00 17.33 0. 0011 0.001 0. 001 0.02 0 0. 00 0 0. 00 17.50 0.0011 ' 0.001 0. 001 0. 02 0 0.00 17. 67 0.0011 0.001 0. 001 0.02 17.83 0.0011 0. 001 0.001 0.02 0 0. 00 0 0. 00 18. 00 0.0011 0.001 18.17 0.0011 0.001 0. 001 0:02 0 0.00 0. 001 0.02 0 0.00 18.33 0.0011 0.001 0. 001 0.02 18.50 0.0011 0.001 0. 001 0.02 0 0. 00 0 0. 00 18. 67 0.0011 0.001 0. 001 0. 02 0 0.00 18.83 0.0011 0.001 19.00 0.0011 0.001 0. 001 0.02.02 0 0. 00 0 0.00 19. 17 0.0011 0.001 0. 001 0.02 0 0. 00 19.33 0.0011 0.001 0. 001 0.02 0 0. 00 19.50 0.0011 0.001 19.67 0.0011 0.001 0. 001 0.02 0 0. 00 0.001 0.02 0 0. 00 19. 83 0.0011 0. 001 0. 001 0. 02 0 0. 00 20. 00 0.0011 0.001 20.17 0.0011 0. 001 0. 02 0 0. 00 0.001 0. 001 0.02 0 20.33 0. 0011 0. 001 0. 001 0.02 0.00 20.50 0. 0011 0.001 0 0. 00 20. 67 0.0011 0.001 0.02 0 0.00 0.001 0. 001 0. 02 0 20.83 0.0011 0. 001 0. 001 0. 02 0. 00 21.00 0.0011 0. 001 0 0. 00 21.17 0.0011 0. 001 0. 001 0. 02 0 0. 00 0. 001 0.02 0 0. 00 21.33 0. 0011 0.001 21.50 0.0011 0. 001 0. 001 0. 02.02 0 0. 00 0 0. 00 21.67 0. 0011 0.001 21. 83 0.0011 0. 001 0. 001 0. 02 0. 001 0.02 0 0. 00 22.00 0.0011 0. 001 0. 001 0. 02 0 0. 00 0 0. 00 22.17 0.0011 0.001 22.33 0.0011 0. 001 0.001 0.02. 02 0 0. 00 0 0.00 PROJECT: Purcell/Meijer Cabin 25 YEAR, 24 HOUR FLOOD ROUTING (B) Outflow via Total Time Inflow Infilt'n Outflow Depth Volume Staging (hrs) (cfs) (cfs) (cfs) (feet) (cu ft) Coef't t Qin Q6 Qtot D V a 22.50 0. 0011 0.001 0.001 0.02 0 0.00 22.67 0.0011 0.001 0.001 0.02 0 0.00 22.83 0.0011 0.001 0.001 0.02 0 0.00 23.00 0.0011 0.001 0.001 0.02 0 0.00 23.17 0.0011 0.001 0.001 0.02 0 0.00 23.33 0.0011 0.001 0.001 0.02 0 0.00 23.50 0.0011 0.001 0.001 0.02 0 0.00 23.67 0.0011 0.001 0.001 0.02 0 0.00 23.83 0.0011 0.001 0.001 0.02 0 0.00 24.00 0.0011 0.001 0.001 0.02 0 0.00 24.17 0.0000 0.000 0.000 0.01 0 0.00 24.33 0.0000 0.000 0.000 0.00 0 0.00 24.50 0.0000 0.000 0.000 0.00 0 0.00 24.67 0.0000 0.000 0.000 0.00 0 0.00 24.83 0.0000 0.000 0.000 0.00 0 0.00 25.00 0.0000 ' 0.000 0.000 0.00 0 0.00