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APPROVED STM Drainage ReportNovember 21, 2020 Drainage Memo Regarding: 17901 Vista Del Mar Drive, Edmonds 98026 Permit application: #BLD2020-0433, 0434 Hitchens Single Family Residence SW2-1 Comment response to meet drainage mitigation requirements -This single-family residence consists of the following impervious area: New Impervious Areas Surface Proposed Area House Main Floor = 2,643 SF Garage Floor = 802 SF Entry Porch = 19 SF Garage Roof Overhang = 159 SF House Roof Overhang = 930 SF Entry Porch Roof Overhang = 137 SF Driveway to Prop. Line = 343 SF Driveway (Prop. Line to Curb) = 208 SF Total Impervious to Curb = 5,241 SF Existing Impervious Area Existing side walk included for original plat = 123 SF -Project drainage to be designed to accommodate 5,241 SF of impervious area. -A drywell system has been designed to accommodate 241 SF -The attached 15-page report by Lovell-Sauerland & Associates, Inc. shows that lot 10 has 5,000 SF of impervious area that has been accounted for and designed into the existing Detention Storage System for the Plat of Vista Del Mar. (See appendix 1) Submitted by: Date: E ?2,20 General ontracto wners Agent Robin Kearsley, K ey Homes Inc. November 21, 2020 Drainage Memo Regarding: 17901 Vista Del Mar Drive, Edmonds 98026 Permit application: #BLD2020-0433, 0434 Hitchens Single Family Residence SW3-1 Drywell Design -As proposed, the new house will have 5,241 ft2 of impervious area. A drywell is shown on the Drainage/Utility Plan D 1.0 to take 241 sf of roof rain water. -The short driveway from the house will slope to the street and runoff water will be diverted into the existing catch basin in Vista Del Mar Drive. The catch basin is approximately 15' from the southwest corner of the driveway as it meets the street. -The existing soil type of the drywell was determined from the Boring location B-3 from Nelson Geotechnical Assoc, Inc. Soil Report Dated December 20, 2018, file# 1065318, figure 7. Soil type is orange brown, fine to coarse sand with silt, gravel. The drywell is sized as per Checklist 13: Downspout Full Infiltration Systems, Modeling and Sizing (SWMMWW Volume 111, Section 3.1.1) -Infiltration drywell is seized based on underlying soil type as follows: • Coarse sand and cobble: 60 cubic feet of gravel per 1,000 square feet of contributing impervious surface • Medium sand: 90 cubic feet of gravel per 1,000 square feet of contributing impervious surface -Using checklist 13 the calculation for the drywell size is (241 / 1000) * 90 CF = 21.96 (min) CF -Drywell to be 5ft X 5ft X 2.2ft deep = 55 CF Submitted by: Date: 7--0 General Contractor & Qers Agent Robin Kearsley, Kearsley Homes Inc. APPENDIX 1 DETENTION STORAGE CALCULATIONS AND DRAINAGE BASIN REPORT FOR PLAT OF VISTA DEL MAR ON OLYMPIC VIEW DRIVE AT 92ND AVE W, EDMONDS e, LOVELL-SAUERLAND & ASSOCIATES, INC. 19400 33rd Avenue W. Lynnwood, WA 98036 DETENTION STORAGE CALCULATIONS AND DRAINAGE BASIN REPORT FOR PLAT OF VISTA DEL MAR on Olympic View Drive at 92nd Avenue West, Edmonds t D ' tj A,-,.• Prepared By: yp . $EXPRES----7 >. 4 PROPOSED DEVELOPMENT AND EXISTING CONDITONS The project consists of the subdivision of several contiguous land parcels into approximately 15 lots for construction of single family dwellings. Subdivision improvements would include the construction of public and private roads, utilities, and a storm water collection system. The properties are situated at the top of a bluff adjacent to Puget Sound. A 100 foot wide Burlington Northern Railroad right-of-way lies between Puget Sound and the property. The site is currently occupied by two houses and some small out -buildings. The smaller of the houses lies at the south boundary of the site, and is accessed by an off -site private road from the south. The larger house lies near the center of the site, and is accessed by a looped driveway having a total length of about 1000 feet. About a half of the site is clear of trees and brush, and has historically been lawn with large landscape shrubs and trees. The remainder of the site is covered with second growth evergreen forest. Existing Sanitary sewer and storm drainage systems cross the northernmost portion of the site. The northern portion of the site is accessed by easement through an adjacent single family lot. EXISTING DRAINAGE CONDITIONS All surface runoff from the site eventually drains to the drainage ditch in the BNRR right-of-way. Most is apparently transported by direct overland flow, but_sorne-from the site's forested area is possibly collected in the private systems to the south. These private systems would also eventually discharge in the same BNRR ditch. The ditch drains to the 18-inch culvert crossing under the tracks adjacent to the site. The northernmost end of the piped storm drainage system crossing the site discharges into Puget sound just north of the site. It -drains a basin which includes roughly 155 acres, but does not currently include any significant portion of the site. This basin is discussed in detail below, as it is proposed to use this system to convey future developed runoff. A study of the overall basin was completed by URS Consultants for the City of Edmonds, as documented in their report "Edmonds Drainage Basin Studies" dated June 1989. The basin was one of several subbasins identified in the Talbot Park Drainage Basin. Portions of the study relating to this basin were provided in a preliminary report to the City dated 4/23/93 (by Lovell-Sauerland). It was noted that the elements in the area of Lovell-Sauerland and Associates August 23, 1996 Page 2 the project in general had sufficient capacity to convey the 100 year storm in a future "built -out" basin. Upstream system capacities (above the proposed development) fall well short of the requirements for this particular design storm. DRAINAGE ISSUES The drainage improvements must address two basic issues. First, it is considered desirable to reduce or eliminate surface runoff onto or near the face of the bluff. In particular, concentrated flows from impervious areas must be collected and safely conveyed so as not to increase erosion on the face of the bluff. Due to the BNRR right-of-way and the intolerance the BNRR has demonstrated for improvements by others in land they control, and due to the steepness of the bluff sloping to the BNRR right-of-way, it is not considered feasible to convey storm runoff by any new piped system to Puget Sound, or to the BNRR ditch. Storm runoff must be conveyed by pipe to the existing storm sewer crossing the property. The proposed runoff collection system accomplishes this. The second issue is whether the runoff can be released without control or whether it must first be detained to match existing peak runoff levels. To answer this, the capacity needs of the upstream basin and available capacity of the downstream system were reviewed. The details of this study are at the end of this report in Appendix A. The study showed that even at a maximum capacity of 55 cfs, the last pipe in the downstream system is still undersized for the 100-year peak runoff from the basin of 65.63 cfs. Therefore, the Vista Del Mar project will require detention to comply with city code. The detention will not eliminate the potential flooding, but will mitigate any possible impact by the Vista Del Mar development. In summary, given the apparent lack of downstream pipe capacity, the project will need to provide detention for the plat because: The entire upstream basin produces a calculated runoff greater than the capacity of that pipe, and 2. Even though the pipe network feeding that pipe is of a lower capacity, it cannot be guaranteed on paper that the combination of pipe and gutter flow would not deliver enough water to overflow it. It also cannot be guaranteed that the City won't correct the existing upstream capacity deficiencies. 3. The potential flooding of the BNRR property is an existing situation which may occur, with or without the plat. Construction of the plat will likely result in a small incremental increase in the probable maximum flow. 4. Construction of a detention system for the plat will not eliminate this problem. It Lovell-Sauerland and Associates August 23, 1996 page 3 will only mitigate the new plat's share of the problem, and "prove" that the plat is not a contributor to future flooding. Since there is a potential downstream problem, which the plat may aggravate, the letter of the code must be fulfilled to limit future liability. DETENTION CALCULATIONS Calculations and the drainage plan were completed to meet City of Edmonds 1995 standards, using an SCS-SSUH analysis. Since there is no downstream natural watercourse, the criteria used includes restriction of 10-year and 100-year flows to match the existing runoff for each of those events. The model used for the analysis is called WaterWorksT`", which was developed by Engenious Systems Inc. The program generates runoff hydrographs for each design basin area and allows them to be routed through various configurations of storage and discharge structures. Through a process of trial and error, a configuration is found that meets the criteria for the design storm. Due to the topography of the site, two detention pipes and a water quality swale are proposed. All of the impervious areas of the site will be conveyed by the biofiltration swale. About a 1/4 acre of the site bypasses the detention facilities, but the calculations demonstrate that the release criteria are met by comparing the sum of all developed release hydrogaphs with the existing site runoff. It is noted that although the sum of pipe discharges and the bypass peak flows exceed the allowable discharge, the peaks do not all occur at the same time and the peak of the total discharge hydrograph is less. Assumptions used for the detention calculation include: Site soils are of hydrologic group "C" 2. One offsite house will drain to the detention system, making a total of 3 existing homes. The total existing impervious area on and offsite is over 20,000 square feet. However, it is assumed that only 5,000 sf per home exists for the existing homes on the site. New impervious is assumed to be the area of the roads, plus 5,000 sf per lot. 3. The design storms are per the City's new ordinance. 4. Yard areas of lots 7-10 and 13-15 are already grass, and have been historically. The hydrologic character of these areas will not change, and they are not included in the calculation. Runoff from these areas can be routed to the drainage system, but will bypass the detention. 5. Existing conditions are assumed to be 50. percent second growth forest and 50 percent meadow (with some existing impervious). Lovell-Sauedand and Associates August 23, 1996 Page 4 SCS weighted average curve number calculations, are attached. Detailed detention storage calculations follow. A. DETENTION SUMMARY TABLE Recurrence interval: 10-Year 100-Year Exist. development area runo, 0.40 cfs 0.92 cfs Peak pipe design discharge' Pipe in Kairez DriV / 0.15 cfs 0.44 cfs Pipe in Nicholas Lne 0.09 cfs 0.36_ cfs Peak runoff from bypass, urea 0.24 cfs:, ' 0.42 cfs Design discharge (deten aon 0.42 cfs 0.92,E pipes + bypass) Design detention storage,., Pipe in Kairez Drivel 4,064 cf 5,752 cf Pipe in Nicholas Lane 1,915 cf 2,363 cf P Note: Since the waterworks program does riot model CMPA, and does not allow the inclusion of structures, the ultimate detentioon, pipe configuration is based on the attached spreadsheets labelled "Detention pipe'for Nicholas Lane" and "Detention pipe for Kairez Place." These provid$ the final-plpD and,orifice sike and location. B. DETENTION CALCULATION DETAILS -- Waterworks printout Waterworks batch file: MOVE 10B TO 3 , �t y�✓. 1� ' .tom fZr, MOVE OOB TO 13li MOVE 10E TO 9 MOVE OOE TO 19 LPOOL 1 "10-YEAR KAIREZ" HE IOFK PIPEK CTRLK 1 LPOOL 2 "100-YEAR KAIREZ" OOE OOFK PIPEK CTRLK 11 LPOOL 4 "10-YR NICHOLAS" 10E 1OFN PIPEN CTRLN 2 LPOOL 5 "100-YR NICHOLAS" OOE OOFN PIPEN CTRLN 12 ADD 1 2 4 ADD 3 4 10 ADD 11 12 14 ADD 13 14 20 8/22/96 Lovell-Sauerland & Associates Inc page 1 Lovell-Sauerland and Associates August 23, 1996 Page 5 BASIN SUMMARY BASIN ID: OOE NAME: 100-YEAR EXISTING }. SBUH METHODOLOGY TOTAL AREA.......: 3.99 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERVIOUS AREA ' PRECIPITATION....: 3.00 inches AREA..: 3.65 Acres TIME INTERVAL..... 10.00 min CN..... 82.80 ` TIME OF CONC.....: 31.11 min IMPERVIOUS AREA ,+ € ABSTRACTION COEFF: 0.20 AREA..: 0.34 Acres CN..... 98.00' TcReach - Sheet L: 280.00 ns:0.4000 p2yr: 1.50 s:0.1600 PEAK RATE: 0.92 cfs VOL: 0.51 Ac-ft TIME: 490 min t BASIN ID: OOFB NAME: 100-YEAR DEVELOPED BYPASS SBUH METHODOLOGY t TOTAL AREA.......: .0.27 Acres BASEFLOWS: 0.00 cfs ` RAINFALL TYPE....: TYPEIA PERVIOUS AREA t' PRECIPITATION....: 3.00 inches AREA..: 0.00 Acres TIME INTERVAL....: 10.00 min CN....: 85.50 r TIME OF CONC.....: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 0.27 Acres 6 CN..... -�8;00 PEAK RATE: 0.16 cfs VOL: 0.06 Ac-ft TIME: 480 min BASIN ID: OOFK NAME: 100-YEAR DEVELOPED IMIREZ LANE SBUH METHODOLOGY; TOTAL AREA.......: 2.71 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERVIOUS AREA PRECIPITATION....: 3.00 inches AREA..: 1.22 Acres. TIME INTERVAL....: 10.00 min CN....: 85.50'`: TIME OF CONC.....: 14.60 min IMPERVIOUS AREA; ABSTRACTION COEFF: 0.20 AREA..: 1.49 Acres CN..... HAN TcReach - Sheet L: 290.00 ns:0.1500 p2yr: 1.50 s:0.1600 PEAK RATE: 1.23 cfs VOL: 0.51 Ac-ft TIME: 480 min , s 8/22/96 Lovell-Sauerland & Associates Inc page 2 k BASIN SUMMARY x BASIN ID: OOFN NAME: 100-YEAR DEVELOPED NICHOLAS LN SBUH METHODOLOGY TOTAL AREA.......: 1.02 Acres BASEFLOWS: 0,00 cfs ° RAINFALL TYPE....: TYPEIA PERVIOUS AREA PRECIPITATION....: 3.00 inches AREA..: 0.00 Acres �a TIME INTERVAL....: 10.00 min CN....: 85.50 TIME OF CONC.....: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 3.02 Acres CN....: 98.00 6 PEAK RATE: 0.61 cfs VOL: 0.23 Ac-ft TIME: 480 minF Love!!-Sauerland and Associates August 23, 1996 Page 6 BASIN ID: 10E NAME: 10-YEAR EXISTING SBUH METHODOLOGY TOTAL AREA.......: 3.99 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERVIOUS AREA PRECIPITATION....: 2.00 inches AREA..: 3.65 Acres TIME INTERVAL....: 10.00 min CN....: 82.80 TIME OF CONC.....: 31.11 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 0.34 Acres CN..... 98.00 TcReach - Sheet L: 280.00 ns:0.4000 p2yr: 1.50 s:0.1600 PEAK RATE: 0.40 cfs VOL: 0.26 Ac-ft TIME: 490 min BASIN ID: 10FB NAME: 10-YEAR DEVELOPED BYPASS SBUH METHODOLOGY TOTAL AREA.......: 0.27 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERVIOUS AREA PRECIPITATION....: 2.00 inches AREA..: 0.00 Acres TIME INTERVAL....: 10.00 min CN....: 85.50 TIME OF CONC.....: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 0.27 Acres CN..... 98.00 PEAK RATE: 0.11 cfs VOL: 0.04 Ac-ft TIME: 480 min 8/22/96 Lovell-Sauerland & Associates Inc page 3 BASIN SUMMARY BASIN ID: 10FK NAME: 10-YEAR KAIREZ DEVELOPED SBUH METHODOLOGY TOTAL AREA.......: 2.71 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERVIOUS ARIM PRECIPITATION..... 2.00 inches AREA... 1.22 Acres TIME INTERVAL....: 10.00 min CN....: 85.50 TIME OF CONC.....: 14.60 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 1.49 Acres CN..... 98.00 TcReach - Sheet L: 290.00 ns:0.1500 p2yr: 1.50 s:0.1600 PEAK RATE: 0.72 cfs VOL: 0.30 Ac-ft TIME: 480 min BASIN ID: 10FN NAME: 10-YEAR DEVELOPED NICHOLAS SBUH METHODOLOGY TOTAL AREA.......: 1.02 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPEIA PERVIOUS AREA PRECIPITATION....: 2.00 inches AREA..: 0.00 Acres TIME INTERVAL....: 10.00 min CN....: 05.50 TIME OF CONC.....: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 1.02 Acres CN..... 98.00 PEAK RATE: 0.40 cfs VOL: 0.15 Ac-ft TIME: 480 min 8/22/96 Lovell-Sauerland & Associates Inc page 4 Lovell-Sauerland and Associates August 23, 1996 Page 7 HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf-AcFt Acres 1 0.154 810 13184 cf 2.71 2 0.087 690 6547 cf 1.02 3 0.238 480 4010 cf 0.91 4 0.240 800 19731 cf 3.73 9 0.399 490 11207 cf 3.99 10 0.418 480 23741 cf 4.64 11 0.436 570 22083 cf 2.71 12 0.359 510 10214 cf 1.02 13 0.422 480 6915 cf 0.91 14 0.739 530 32297 cf 3.73 19 0.921 490 22284 cf 3.99 20 0.916 520 39212 cf 4.64 8/22/96 Lovers-Sauerland & Associates Inc page 5 STAGE STORAGE TA9.LE��-QL*i��A-�__.,_..___s� UNDERGROUND PIPE ID No. PIPEK Descriptian: PIPE IN KAIREZ DRIVE Diameter: 7.50 ft. Length: 150.00 ft. Slope...: 0.0050 ft/ft STAGE <---- STORAGE ---- > STAGE <---- STORAGE ---- > STAGE <---- STORAGE ---- > STAGE <---- QTvP.AGE----_ (ft) ---- ---cf--- - ------ --Ac-Ft- ----- (ft) _ ____ ---cf-----Ac-Ft- (i't) ---cf--- --AC-Ft- (ft) ---c£--- --Ac-Ft- 146.00 0.0000 0.0000 --- 148.10 1165 0.0267 150.20 3397 0.0780 152.30 _='- 5600 °-_:-----= 0.1286 146.10 1.1502 0.0000 148.20 1260 0.0289 150.30 3509 0.0806 152.40 5689 0.1306 146.20 6.4801 0.0001 148.30 1356 0.0311 150.40 3621 0.0831 152.50 5777 0.1326 146.30 17.782 0.0004 148.40 1455 0.0334 150.50 3732 0.0857 152.60 5861 0.1346 146.40 36.354 0.0008 148.50 1554 0.0357 150.60 3844 0.0882 152.70 5943 0.1364 146.50 63.244 0.0015 148.60 1656 0.0300 150.70 3954 0.0908 152.80 6022 0.1382 146.60 99.344 0.0023 148.70 1758 0.0404 150.60 4065 0.0933 152.90 6097 0.1400 146.70 145.44 0.0033 148.80 1862 0.0428 150.90 4174 0.0958 153.00 6169 0.1416 146.80 192.62 0.0044 148.90 1968 0.0452 151.00 4284 0.0983 153.10 6237 0.1432 146.90 241.05 0.0055 149.00 2074 0.0476 151.10 4392 0.1008 153.20 6300 0.1446 147.00 296.51 0.0068 149.10 2181 0.0501 151.20 4500 0.1033 153.30 6359 0.1460 147.10 357.57 0.0082 149.20 2289 0.0525 151.30 4606 0.1057 153.40 6411 0.1472 147.20 423.35 0.0097 149.30 2398 0.0550 151,40 1712 0.1082 153.50 6454 0.1482 147.30 493.35 0.0113 149.40 2507 0.0576 151.50 4817 0.1106 153.60 6506 0.1494 147.40 567.08 0.0130 149.50 2617 0.0601 151.60 4920 0.1129 153.70 6547 0.1503 147.50 644.19 0.0148 149.60 2728 0.0626 151.70 5022 0.1153 153.80 6578 0.1510 147.60 724.46 0.0166 149.70 2838 0.0651 151.80 5122 0.1176 153.90 6601 0.1515 147.70 807.63 0.0185 149.80 2951 0.0677 151.90 5222 0.1199 154.00 6616 0.1519 147.80 893.44 0.0205 149.90 3061 0.0703 152.00 5319 0.1221 154.10 6624 0.1521 147.90 981.75 0.0225 150.00 3174 0.0729 152.10 5415 0.1243 154.20 6627 0.1521 148.00 1072 0.0246 150.10 3286 0.0754 152.20 5500 0.1265 154.25 6627 0.1521 8/22/96 Lovell-Sauerland 6 Associates Inc page 6 Lovell-SaueHand and Associates August 23, 1996 Page 8 STAGE STORAGE TABLE� UNDERGROUND PIPE ID No. PIPEN Description: PIPE IN NICHOLAS LANE Diameter: 5.00 ft. Length: 150.00 ft. Slope...: 0.0050 ft/ft STAGE < ---- STORAGE ---- > STAGE <---- STORAGE ---- > STAGE <---- STORAGE----> STAGE <---- STORAGE----> (ft) --- cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf-----Ac-Ft- (ft) ---cf--- --Ac-Ft- 95.00 0.0000 0.0000 96.50 510.10 0.0117 98.00 1565 0.0359 99.50 2581 0.0592 95.10 0.9370 0.0000 96.60 572.26 0.0131 98.10 1639 0.0376 99.60 2634 0.0605 95.20 5.2689 0.0001 96.70 636.32 0.0146 98.20 1713 0.0393 99.70 2684 0.0616 95.30 14.431 0.0003 96.80 702.09 0.0161 98.30 1786 0.0410 99.80 2731 0.0627 95.40 29.435 0.0007 96.90 769.36 0.0177 98.40 1859 0.0427 99.90 2772 0.0636 95.50 51.094 0.0012 97.00 837.98 0.0192 98.50 1931 0.0443 100.00 2607 0.0644 95.60 80.083 0.0018 97.10 907.75 0.0208 98.60 2002 0.0460 100.10 2848 0.0654 95.70 116.96 0.0027 97.20 978.59 0.0225 98.70 2073 0.0476 100.20 2881 0.0661 95.80 154.57 0.0035 97.30 1050 0.0241 98.80 2142 0.0492 100.30 2906 0.0667 95.90 193.13 0.0044 97.40 1123 0.0258 98.90 2210 0.0507 100.40 2924 0.0671 96.00 237.19 0.0054 97.50 1196 0.0274 99.00 2276 0.0523 100.50 2936 0.0674 96.10 285.54 0.0066 97.60 1269 0.0291 99.10 2341 0.0537 100.60 2943 0.0676 96.20 337.43 0.0077 97.70 1343 0.0308 99.20 2404 0.0552 100.70 2945 0.0676 96.30 392.37 0.0090 97.80 1417 0.0325 99.30 2465 0.0566 100.75 2945 0.0676 96.40 450.03 0.0103 97.90 1491 0.0342 99.40 2524 0.0580 8/22/96 Lovell-Sauerland & Associates Inc page 7 STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. CTRLK Description: KAIREZ DRIVE CONTROL STRUCTURE Structure: OK Structure: Structure: RK Structure: Structure: STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHAARGE---> STAGE <--DISCHARGE --- > (ft) --- cfs-- ------- (ft) r148.30--- --- cfs-- ------- (ft) p --- cfs--------- (ft) --- cfs--------- 146.00 0.0000 0.1,067150.600.1503152.90 -=- =~- =---'--=--- -- ==- 0.47501V�s_==�= 146.10 0.0222 149.40 0.1090 150.70 0.1525 153.00 0.4835 146.20 0.0315 148.50 0.1112 150.80 0.1541 153.10 0.4918 146.30 0.0385 148.60 0.1134 150.90 0.1557 153.20 0.5000 146.40 0.0445 148.70 0.1156 151.00 0.2222 153.30 0.5080 146.50 0.0497 148.80 0.1177 151-.10 0.25-06 153.40 0.5158 146.60 0.0545 148.90 0.1198 151.20 0.2728 153.50 0.5236 146.70 0.0589 149.00 0.1218 151.30 0.2917 153.60 0.5311 146.80 0.0629 149.10 0.1238 151.40 0.3086 153.70 0.5386 146.90 0.0667 149.20 0.1258 151.50 0.3239 153.80 0.5459 147.00 0.0703 149.30 0.1278 151.60 0.3382 153.90 0.5532 147.10 0.0738 149.40 0.1297 151.70 0.3515 154.00 0.5603 147.20 0.0771 149.50 0.1316 151.80 0.3641 154.10 0.8753 147.30 0.0802 149.60 0.1335 151.1�0 0.3761 154.20 1.4453 147.40 0.0832 149.70 0.1353 152.60 0.3875 154.30 2.1813 147.50 0.0862 149.80 0.1371 152.10 0.3985 154.40 2.9798 147.60 0.0890 149.90 0.1389 152.20 0.4091 154.50 3.2687 147.70 0.0917 150.00 0.1407 152.30 0.4194 154.60 3.5306 147.80 0.0944 150.10 0.1424 152.40 0.4293 154.70 3.7718 147.90 0.0970 150.20 0.1442 152-50 0.4389 154.80 3.9967 148.00 0.0995 150.30 0.1459 152.60 0.4483 154.90 4.2082 148.10 0.1019 150.40 0.1476 152.70 0.4574 155.00 4.4086 148.20 0.1043 150.50 0.1492 152.80 0.4663 Lovell-Sauedland and Associates August 23, 1996 page 9 8/22/96 Lovell-Sauerland & Associates Inc page 8 STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. CTRLN Description: NICHOLAS LANE CONTROL STROCT Structure: ON Structure: Structure: RN Structure: STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > (ft) --- cfs--------- (ft) --- cfs--------- (ft) --- cfs--------- (ft) --- cfs--------- 95.00 0.0000 96.60 0.0589 98.20 0.0833 99.80 0.4811 95.10 0.0147 96.70 0.0607 98.30 0.0846 99.90 0.4964 95.20 0.0208 96.80 0.0625 98.40 0.0859 100.00 0.5113 95.30 0.0255 96.90 0.0642 98.50 0.0871 100.10 0.5257 95.40 0.0295 97.00 0.0659 98.60 0.1935 133.20 0.5396 95.50 0.0329 97.10 0.0675 98.70 0.2382 100.30 0.5532 95.60 0.0361 97.20 0.0691 98.80 0.2729 100.40 0.5664 95.70 0.0390 97.30 0.0706 98.SO 0.3022 100.50 0.5793 95.80 0.0417 97.40 0.0721 99.0 0.3282 100.60 0.8999 95.90 0.0442 97.50 0.0736 99.10 0.3518 100.70 1.4753 96.00 0.0466 97.60 0.0751 99.20 0.3736 100.80 2.2166 96.10 0.0468 97.70 0.0765 99.30 0.3939 100.90 3.0919 96.20 0.0510 97.80 0.0779 99.40 0.4131 101.00 3.3140 96.30 0.0531 97.90 0.0793 99 50 0.4312 96.40 0.0551 98.00 0.0807 99.60 0.4485 96.50 0.0570 98.10 0.0820 99.70 0.4651 8/22/96 Lovell-Sauerland & Associates Inc page 9 STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. OK Description: ORIFICE FOR KAIREZ DRIVE Outlet Elev: 146.00 Elev: 146.00 ft Orifice Diameter: 1.6100 in. Elev: 150.90 ft Orifice 2 Diameter: 2.7500 in. STAGE <--DISCHARGE --- > STAGE <--DISCkhr-RGE --- > STAGE <--DISCHARGE --- > (ft) ---cfs-- ------- (ft) --- cfs--------- (ft) --- cfs-- ------- 146.00 0.0000y 148.30 S 0.1067 µ- - y150.E0 s-0.1509�F'-__ 146.10 0.0222 148.40 0.1090 150.70 0.1525 146.20 0.0315 148.50 0.1112 150.80 0.1541 146.30 0.0385 148.60 0.1134 150.90 0.1557 146.40 0.0445 148.70 0.1156 151..00 0.2222 146.50 0.0497 148.80 0.1177 151 10 0.2506 146.60 0.0545 148.90 0.1198 151.20 0.2728 146.10 0.0589 149.00 0.1218 151.30 0.2917 146.80 0.0629 149.10 0.1238 151.40 0.3086 146.90 0.0667 149.20 0.1258 151.50 0.3239 147.00 0.0703 149.30 0.1278 151.60 0.3382 147.10 0.0738 149.40 0.1297 151.70 0.3515 147.20 0.0771 149.50 0.1316 151.80 0.3641 147.30 0.0802 149.60 0.1335 151.90 0.3761 147.40 0.0832 149.70 0.1353 152.00 0.3875 147.50 0.0862 149.80 0.1371 152.10 0.3985 147.60 0.0890 149.90 0.1389 152.20 0.4091 147.70 0.0917 150.00 0.1407 151'.30 0.4194 147.80 0.0944 150.10 0.1424 152.40 0.4293 147.90 0.0970 150.20 0.1442 152.50 0.4389 148.00 0.0995 150.30 0.1459 152.60 0.4483 148.10 0.1019 150.40 0.1476 152.70 0.4574 148.20 0.1043 150.50 0.1492 152.80 0.4663 STAGE <--DISCHARGE---> (ft) --- cfs--------- 152.90- _ 0.4750 153.00 0.4635 153.10 0.4918 153.20 0.5000 153.30 0.5080 153.40 0.5158 153.50 0.5236 153.60 0.5311 153.70 0.5386 153.80 0.5459 153.90 0.5532 154.00 0.5603 154.10 0.5673 154.20 0.5742 154.30 0.5811 154.40 0.5878 154.50 0.5945 154.60 0.6010 154.70 0.6075 154.80 0.6140 154.90 0.6203 155.00 0.6266 Lovell-Sauerland and Associates August 23, 1996 Page 10 8/22/96 Lovell-Sauerland i Associates Inc page 10 STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No_ ON Description: ORIFICE IN NICHOLAS LANE Outlet Elev: 95.00 Elev: 95.00 ft Orifice Diameter: 1.3100 in. Elev: 98.50 ft Orifice 2 Diameter: 3.5000 in. STAGE (ft) <--DISCHARGE --- > --- ------- STAGE <--DISCHARGE---> STAGE <--DISCHARGE --- > STAGE <--DISCHARGE---> __=__vim=T=__..__ cfs-- (ft) ---cfs--------- '=- (ft) ---cfs--------- (ft) --- cfs-- 95.00 0.000096.60---0.0589 98,20--~0.0833 99 80- 0_4811 95.10 95.20 0.0147 0.0208 96.70 96.80 0.0607 0.0625 98.30 0.0846 99.90 0.4964 95.30 0.0255 96.90 0.0642 98.40 98.50 0.0859 0.0871 100.00 100.10 0.5113 0.5257 95.90 95.50 0.0295 0.0329 97.00 0.0659 98.60 0.1935 100.20 0.5396 95.60 0.0361 97.10 97.20 0.0675 0.0691 98.70 0.2382 100.30 0.5532 95.70 0.0390 97.30 0.0706 90.80 98.90 0.2729 0.3022 100.40 0.5664 95.80 0.0417 97.40 0.0721 99.00 0.3282 100.50 100.60 0.5793 0.5919 95.90 96.00 0.0442 0.0466 97.50 97.60 0.0736 0.0751 99.10 0.3518 100.70 0.6043 96.10 0.048E 97.70 0.0765 99.20 99.30 0.3736 0.3939 100.80 100.90 0.6163 0.6281 96.20 96.30 0.0510 0.0531 97.80 0.0779 99.40 0.4131 101.00 0.6397 97.90 0.0793 99.50 0.4312 96.40 0.0551 98.00 0.0807 99.60 0.4485 96.50 0.0570 98.10 0.0820 99.70 0.4651 8/22/96 Lovell-Sauerland & Associates Inc page 11 STAGE DISCHARGE -TABLE -=-�`-__=__T=-� RISER DISCHARGE DISCHARGE ID No. RK Description: RISER IN KAIREZ DRIVE Riser Diameter (in): 12.00 elev: 154.00 ft Weir Coefficient...: 3.782 height: 155.00 ft Orif Coefficient...: 9.739 increm: 0.10 ft STAGE <--DISCHARGE --- > STAGE (ft) --- cfs--------- <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > (ft) ---cfs --------- (fit) ---cfs-- ------- (ft) --- cfs-- 154.00 0.0000 154.20 0.8711 154.50 2.6743 154.00 3.3827 154.00 0.0000 154.30 1.6003 154.60 2.9295 154.90 3.5879 154.10 0.3080 154.40 2.3919 154.70 3.1642 155.00 3.7820 8/22/96 Lovell-Sauerland & Associates Inc pa.,}¢ 12 STAGE DISCHARGE TABLE RISER DISCHARGE ID No. RN Description: RISER IN KAIREZ DRIVE Riser Diameter (in): 12.00 elev: 100.50 ft Weir Coefficient...: , 3.782 height: 101.00 ft Orif Coefficient...: 9.739 increm: 0.10 ft STAGE <--DISCHARGE --- > (ft) ---cfs-- STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > ------- (ft) --- cfs-- ------- (ft) --- cfs--------- (ft) --- cfs--------- Lovell-Sauerland and Associates August 23, 1996 Page 11 100.50 0.0000 100.60 0.3080 100.80 1.6003 101.00 2.6743 100.50 0.0000 100.70 0.8711 100.90 2.4638 101.00 2,6743 8/22/96 Lovell-Sauerland & Associates Inc page 13 LEVEL POOL TABLE SUMMARY MATCH INPLUK -STO- -DIS- <-PEAK-> STORAGE <-------- DESCRIPTION --------- > (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) 10-YEAR KAIREZ ............... 0.40 0.72 PIPEK CTRLK 150.80 1 4064.24 100-YEAR KAIREZ .............. 0.92 1.23 PIPEK CTRLK 152.47 11 5752.49 10-YR NICHOLAS ............... jJ` 0.40 PIPEN CTRLN 98.48 2 1915.09 100-YR NICHOLAS ..........»..,,• 4� 0.61 PIPEK CTRLN 99.13 12 2363.08 0; Stu is I�.�.. G1 V`Xk 3 i Vic. � \ � f` LUCJ 116av_ flM LAO Lovell-SaueHand and Associates August 23, 1996 Page 12 DRAINAGE CALCULATIONS 23-Aug-96 DETENTION PIPE FOR KAIREZ PLACE 08:50 AM DETENTION PIPE SIZE Estimate of required detention storage volume = 6000 d Assume a det. pipearch 117.0 x 79.0 (width and height) Cross section area = 52.0 sf Usable vol, of Type 1 CB 6.0 soft = cf Usable vol. of 2.0 Type If MH 54.0 inch dia = 209.4 cf Usable vol. of Type II MH 72.0 inch dia = cf Usable vol. of 18.0 inch pipe: ft long = cf Usable vol. of 36.0 inch pipe: 4.0 It long = 28.3 cf `A Required pipe volume = 5762.3 cubic feet Required pipe length = 110.8 linear feet Length of pipe used = 111-0 FT- Storage provided = 6009.7 cubic feet & p Minimum grade elevations:�,�, �� a+ E jar(• Top D/S detention CB 156.19 with 2.50 it Overflow clearance_., Top D/S detention CB 155.08 with 2.0 ft cover Top U/S detention CB 155.69 with 2.0 It cover �'V1 Min Grnd surf. elev = 154.19 (over any inlet: 0.5 ft above OF / V� C` Inv elev at U/S end = 147.06 Max water surface elev = 153.69 (detn. pipe sl. = 0-51)°k) Invert elevation = 146.50 CALCULATION OF OUTLET SIZE .d" Gj�f41`�/ ky Required release rate, orifice 1 = � 04!0 i' Required release rate, orifice 2 = 0.z70 Required release rate, orifice 3 = r" ✓ ,r Storage At elevation: H, ft a, sf d,ft d,inches provd. ---------------------------------------- --- ------------ -------------- - -------- _-----------. 146.50 6.63 0.015 0.14 1 - 11/16 0 F 150.50 2,63 0.033 0.21 2- 1 /2 4052 F �� Full storage = 6010 area, a = Qdo / (.62 x (2 x g x h)".5) g - 32.2 orifice diameter, d = (4/pi x a)".5 r.3 06 100-YEAR TARGET 04 02 ( �i ro 10-YEAR TARGET § IT 04 0 2 4 6 e Thou"rds Detention Volume, cubic feet DRAINAGE CALCULATIONS 23-Aug-96 DETENTION PIPE FOR NICHOLAS LANE 08:53 AM DETENTION PIPE SIZE Estimate of required detention storage volume = 2b00 cf Assume a det. pipe 72.0 Inches, diameter Cross section area = 28.3 sf Usable vol. of Type i CB 6.0 sf/ft = cf Usable vol. of 2.0 Type II MH 54.0 inch dia = 190 9 d Usable vol. of Type 11 MH 72.0 inch dia = d Usable vol. of 18.0 Inch pipe: ft long = cf Usable vol. of 36.0 inch pipe: 4.0 ft tong = 28.3 d Required pipe volume = 2280.9 cubic feet Required pipe length = 80.7 linear feet Length of pipe used = 81.0 FT. Storage provided = 2509.3 cubic feet Minimum grade elevations: Top D/S detention CB 103.96 with 2.50 ft Overflow clearance Top D/S detention CB 103.00 with 2.0 It cover Top U/S detention CB 103.46 with 2.0 ft cover Min Grnd surf. elev = 101.96 (over any inlet: 0.5 ft above OF; Inv elev at U/S and = 95AI Max water surface elev = 101.46 (detn. pipe sl. = 0.50%) Invert elevation = 95.00 CALCULATION OF OUTLET SIZE Required release rate, orifice 1 = 0.100 r ' �A,. Required release rate, orifice 2 = 0.350� Required release rate, orifice 3 =' Storage ,,• At elevation: H. ft a, sf d,ft d,inches provd. ;. 95.00 6.05 0.008 0.10 1 - 3/18 0 99.50 1.55 0.057 0.27 3- 1/4 1968 0 Full storage = -+- _ 2509 --------------------- ----------- -------------- -- ---- - --- ----------- -- area,a=Qdo/(.62x(2xgxh)`".5) g=32.2 I V y sf orifice diameter, d = (4/pi x a)".5� '- 09 ' "' co N 0 6 1 4 �. i fCn ir i 04' 100-YEAR TARGET c .a- c0 4 F- 1-04EAR TARGET ?, l 0 1 2 3 7lwusands dip Detention Volume, cubic feet %RSTA DEL MAR. LSA 2926 23-Aug-98 SCS Weighted average curve number calculations 08:54 AM SCS Hydrologic Sails type:--> C C EXISTING BASIN n/a n/a TOTAL Basin area, sf. 174,000 0 0 174.000 Basin area, acres: 3.99 0.00 0.00 3.99 Existing conditions (in square feet) Assumptions: CN: Undisturbed forest land 76 Second growth forest 81 Meadow or pasture 85 Grass, > 75% coverage 86 Dirt road/parking lot 87 Gravel mad/parking lot 89 Grass, > 50% coverage 90 Orchard with crop cover 92 Cultivated land 94 Impervious 98 Existing onsite impervious =. 13,900 Open water 100 Total Weighted CN for each basin: Pervious: Area, acres: Weighted CN: Impervious: Area, acres: Percent impervious area: Future conditions Total AC: Total sf: Assumptions: CN: Undisturbed forest land 76 Second growth forest (@ 10% of grass) 81 Meadow or pasture 85 Grass, > 75% coverage 86 Dirt road/parking lots 87 Gravel road/parking tot 89 Grass, > 50% coverage 90 Orchard with crop cover 92 Cultivated land 94 Impervious 98 Other impervious LF of road/sidewalk, plat road: Avg. Width of road/sidewalk 30 ft LF of road/sidewalk, frontage: Avg. Width of road/sidewalk 25 ft No. of houses/lots House/lot impervious 5,000 sflot Open water 100 Total Weighted CN for each basin: ----------------------------------------------------------------- Pervious: Area, acres: Weighted CN: Impervious: Area, acres: Percent impervious area: 87,000 72,000 15,000 CN: 76 81 85 86 87 89 90 92 94 98 0 100 84.1 76.0 3.65 0.00 82.8 76.0 0.34 8.6% Detention 1 2.71 118,000 4,818 48,182 65,000 5,000 500 200 8 5,000 92.4 1.22 85.5 1.49 55.1 % CN: 76 81 85 86 87 89 90 92 94 98 100 Detention 2 1.02 44,250 0 0 44,250 8,000 250 6 5,000 98.0 0.00 85.5 1.02 100.0% 0 0 87.000 72,000 15,000 76.0 84.1 0.00 3.65 76.0 82.8 0.34 8.6% bypass TOTAL 0.27 3.99 11,750 174,000 0 4,818 0 48,182 11,750 121,000 1.760 14.750 500 450 2 16 5,000 98.0 94.2 0.00 1.22 85.5 86.6 0.27 2.78 100.0% 69.51.E