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Vista Del Mar Detention Storage CalculationsLOVELL-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 vl•J 1.1 k'1% kfAt S L2 K14 f o ,6L01 l� 4k Li Prepared By: S J `.s i • �: a� ')io��1gL 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 some 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-Sauertand and Associates August23, 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-Sauedand 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-SBUH 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 1. 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 runoff 0.40 cfs 0.92 cfs Peak pipe design discharge Pipe in Kairez Drive 0.15 cfs 0.44 cfs Pipe in Nicholas Lane 0.09_cfs 0 36 cfs Peak runoff from bypass area 0.24 cfs, 0.42 cfs Design discharge (detention 0.42 cfs 0.92 cfs pipes + bypass) Design detention storage Pipe in Kairez Drive 4,064 cf 5.752 of Pipe in Nicholas Lane 1,915 cf 2,363 cf • no � ,,,ham Vol b� k•✓^ Note: Since the waterworks program does hot model CMPA, and does not allow the inclusion of structures, the ultimate detention pipe configuration is based on the attached spreadsheets labelled "Detention pipe for Nicholas Lane" and "Detention pipe for Kairez Place." These provide the final pipe and orifice size and location. B. DETENTION CALCULATION DETAILS — Waterworks printout \r waterworks batch file: INC MOVE 1OB TO 3 -� ,/ tip'- ' - %U k. [A`' MOVE OOB TO 13 f'x 1 `� MOVE 10E TO 9 V A 6 J L13 MOVE DOE TO 19 (�� t,,,'T LPOOL 1 "10-YEAR KAIREZ" 10E 1OFK PIPEK CTRLK 1 LPOOL 2 "100-YEAR KAIREZ" DOE OOFK PIPEK CTRLK 11 LPOOL 4 "10-YR NICHOLAS" l0E IOFN PIPEN CTRLN 2 LPOOL 5 "100-YR NICHOLAS" DOE 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 6 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....: TYPElA 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 BASIN ID: OOFB NAME: 100-YEAR DEVELOPED BYPASS SBUH METHODOLOGY TOTAL AREA.......: .0.27 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPElA PERVIOUS AREA PRECIPITATION....: 3.00 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....: .00 PEAK RATE: 0.16 cfs VOL: 0.06 Ac-ft TIME: 480 min BASIN ID: OOFK NAME: 100-YEAR DEVELOPED KAIRE2 LANE SBUH METHODOLOGY TOTAL AREA.......: 2.71 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE....: TYPElA PERVIOUS AREA PRECIPITATION....: 3.00 inches AREA..: 1.22 Acres TIME INTERVAL....: 10.00 min CN....: $5.50 TIME OF CONC.....: 14.60 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA..: 1.49 Acres CN....: T$ 0-6- � 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 8/22/96 Lovell-Sauerland 6 Associates Inc BASIN ID: OOFN SBUH METHODOLOGY TOTAL AREA.......: RAINFALL TYPE .... : PRECIPITATION....: TIME INTERVAL....: TIME OF CONC.....: ABSTRACTION COEFF: ! �:�94:4FY+i3w�:7,y7 NAME: 100-YEAR DEVELOPED ttICHOLAS IN � IS page 2 1.02 Acres BASEFLOWS: 0.00 cfs TYPElA PERVIOUS AREA 3.00 inches AREA..: 0.00 Acres 10.00 min CN....: 85.50 10.00 min IMPERVIOUS AREA 0.20 AREA..: 1.Q2 Acres PEAK RATE: 0.61 cfs VOL: CN....: 98.00 0.23 Ac-ft TIME: 480 min Lovell-Sauedand 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....: TYPElA 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....: TYPElA 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 6 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....: TYPELA PERVIOUS AREA 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 W 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: 1OFN SBUH METHODOLOGY TOTAL AREA.......: RAINFALL TYPE....: PRECIPITATION....: TIME INTERVAL....: TIME OF CONC.....: ABSTRACTION COEFF: NAME: 10-YEAR DEVELOPED NICHOLAS 1.02 Acres TYPELA 2.00 inches 10.00 min 10.00 min 0.20 PEAK RATE: 0.40 cfs VOL: 0 BASEFLOWS: 0.00 cfs PERVIOUS AREA AREA..: 0.00 Acres CN....: 85.50 IMPERVIOUS AREA AREA..: 1.02 Acres CN....: 98.00 15 Ac-ft TIME: 48D min 8/22/96 Lovell-Sauerland 6 Associates Inc page 4 Love#-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 Ll �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 Lovell-Sauerland s ASSoefates Inc page 5 STAGE STORAGE TABLE •av-ei•-s_'�- UNDERGROUND PIPE ID No. PIPES Description: PIPE IN 1UIIREE DRIVE Diameter: 7.50 ft, Length: 150.00 ft. Slope...: 0.0050 ft/ft STAGE <---- STORAGE ---- > STAGE <---- STORAGE ---- > (ft)---of-----Ac-Ft- (ft) --cf----AC-Ft- 146.00 0.0000 0.0000 140.20 1165 0.0267 146.10 1.1502 0.0000 149.20 1260 0.0289 146.20 6.4801 0.0001 148.30 1356 0.0311 146.30 17.782 0.0004 148.40 1455 0.0334 146.40 36.354 0.0008 148.50 1554 0.0357 146.50 63.244 0.0015 148.60 1656 0.0380 146.60 99.344 0.0023 148.70 1758 0.0404 146.70 145.44 0.0033 148.80 1862 0.0428 146.80 192.62 0.0044 148.90 1968 0.0452 146.90 241.05 0.0055 149.00 2074 0.0476 147.00 296.51 0.0068 149.10 2181 0.0501 147.10 357.57 0.0082 149.20 2289 0.0525 147.20 423.35 0.0097 149.30 2398 0.0550 147.30 493.35 0.0113 149.40 2507 0.0576 147.40 567.09 0,0130 149.50 2617 0.06D1 147.50 644.19 0.0148 149.60 2728 0.0626 147.60 724.46 0.0166 149.70 2838 0.0651 147.70 807.63 0.0185 149.80 2951 0.0677 147.80 893.44 0.0205 149.90 3061 0.0703 141.90 981.75 0.0225 150.00 3174 0.0729 148.00 1072 0.0246 250.10 3286 0.0754 STAGE < ---- STORAGE ---- > STAGE <---- STORAGE----: (It) --cf-----Ac-Ft- (ft) --cf---Ac-Ft- 150.20 3391 0.0700 152.30 5600 0.1286 150.30 3509 0.0806 152,40 5689 0.1306 150.40 3621 0.0831 152.50 5777 0.1326 150.50 3732 0,0057 152.60 5661 0.1346 150.60 3844 0.0862 152.70 5943 0.1364 150.70 3954 0.0908 152.80 6022 0.1382 150.50 4065 0.0933 152.90 6097 0.1400 150.90 4174 0.0958 153.00 6169 0.1416 151.00 4284 0.0983 153.10 6237 0.1432 151.10 4392 0.1008 153.20 6300 0.1446 151.20 4500 0.1033 153.30 6359 0.1460 151.30 4606 0.1057 153.40 6411 0.1472 151.40 4712 0.1082 153.50 6454 0.1482 151.50 4817 0.1106 153.60 6506 0.1494 151.60 4920 0.1129 153.70 6547 0.1503 151.70 5022 0.1153 153.80 6578 0.1510 151.80 5122 0.1176 153.90 6601 0.1515 151.90 5222 0.1199 154-00 6616 0.1519 152.00 5319 0.1221 154.10 6624 0.1521 152.10 5415 0.1243 154.20 6627 0.1521 152.20 5500 0.1265 154.25 6627 0.1521 8/22/96 Lovell-Sauerland 4 Associates Inc page 6 Lovell-Sausdand and Associates August 23, 1996 Page 8 ^__�•__~•-a-"ii6'- STAGE STORAGE TABLE ®vRv 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. 70 0. 0117 98.00 1565 0.0359� 99.50 2581 0.0592•i 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 90.30 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 2172 0.0636 95.50 51.094 0.0012 97.00 837.98 0.0192 98.50 1931 0.0443 100.00 2807 0.0644 95.60 80.083 0.0018 97.10 907.75 0.0208 96.60 2002 0.0460 100.10 2648 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 98.90 2142 0.0492 100.30 2906 0.0667 95.90 193.13 0.0044 97.40 1123 0.0258 90.90 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 97.10 1343 0.0309 99.20 2404 0.0552 100.70 2945 0.0616 96.30 392.37 0.0090 97.80 1417 O.D325 99.30 2465 0.0566 100.75 2945 0.0676 96.40 450.03 0.0103 97.90 1491 O.D342 99.40 2524 0.0580 8/22/96 Lovell-Sauerland a Associates Inc page 7 STAGE DISCHARGE-TABLB=---�._..__-_-- COMBINATION DISCHARGE ID No. CTRLR Description: AAIREE DRIVE CONTROL STRUCTURE Structure: OE structure: Structure: RE Structure: Structure: STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > (ft) --- cfs--------- w148.30 (ft) --- cfs-- ------- (ft) --- cfs--------- (ft) ---cfs--------- 146.000.0000-`tom 0.1067 150.6D 0.1509 152.90 0.4750- 146.10 0.0222 148.40 0.1090 150.70 0.1525 153.00 0.4835 146.20 0.0315 148.50 0.1112 150.B0 0.1541 153.10 0.4918 146.30 D.0385 148.60 0.1134 150.90 0.1557 153.20 0.5000 146.40 D.0445 240.70 0.1156 151.00 0.2222 153.30 0.5080 146.50 0.0497 148.80 0.1177 151.10 0.2506 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 0.121E 151.30 0.2917 153.60 0.5311 116.80 0.0629 149.10 0.1239 151.4D 0.3006 153.70 0.5396 146.90 0.0661 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 154.30 0.8753 147.30 0.0802 149.60 0.1335 151.GD 0.3761 154.20 1.4453 147.40 0.0832 149.70 0.1353 152.(0 0.3875 154.30 2.1813 147.50 0.0862 149.80 0.1371 152.10 0.3985 154.40 2.9790 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-Sausdand and Associates August 23, 1996 Page 9 8122/96 Lovell-Sauerland 4 Associates Inc page e STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. CTRIA Description: NICHOLAS LANE CONTROL STRDCT Structure: ON Structure: Structure: RN Structure: STAGE <-DISCHARGE--> STAGE <--DISCHARGE--> STAGE <--DISCHARGE--> STAGE <-DISCHARGE--> (it) ---cfs--------- Ift) ---cfa--------- (ft) --- cfa--------- (ft) ---cfs-- ------ 95.00 0.0000 96.60 0.0589 98.20 0.0833 99.00 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 95.4D 0.0295 97.00 0.0659 98.60 0.1935 100.20 0.5396 95.50 0.0329 97.20 0.0675 98.70 0.2382 100.30 0.5532 95.6D 0.0361 97.20 0.0691 98.80 0.2729 100.40 0.5664 95.70 0.0390 97.30 0.0706 WED 0.3022 100.50 0.5793 95.00 D.0417 97.40 0.0721 99.10 0.3282 100.60 O.B999 95.90 0.0442 97.50 0.0736 99.10 0.3518 100.70 2.4153 96.00 0.0466 97.60 0.0751 99.20 0.3736 100.80 2.2166 96.10 0.0488 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 90.10 O.D820 99.70 0.4651 8/22/96 Lovell-Sauerland c Associates Inc page 9 STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. OE Description: ORIFICE FOR 101IREi DRIVE Outlet Elev: 146.00 Elev: 146.00 ft Orifice Diameter: 1.6100 in. Elev: 150.90 ft Orifice 2 Diameeter: 2.7500 in. STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE--> (it) --- cfs--------- (ft) --- cfs-- ------- (it) --- cfs--------- (ft) --- cis --------- 146.00 0.0000 148.30 0.1067 150.0 0.1509 152.90 0.4150 146.10 0.0222 148.40 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 0.2506 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 151.79 0.3515 154.00 0.5603 147.20 0.0771 149.50 0.1316 151.80 0.3641 154.10 0.5673 147.30 0.0802 149.60 0.1335 151.90 0.3761 154.20 0.5742 147.40 0.0832 149.70 0.1353 152.00 0.3875 154.30 0.5811 147.50 0.0862 149.80 0.1371 152.10 0.3985 154.40 0.5878 141.60 0.0890 149.90 0.1389 152.20 0.4091 154-50 0.5945 147.70 0.0917 150.00 0.1407 15;'.30 0.4194 154.60 0.6010 147.80 0.0944 150.10 0.1424 152.40 0.4293 154.10 0.6075 147.90 0.0970 150.20 0.1442 152.50 0.4389 154.80 0.6140 148.00 0.0995 150.30 0.1459 152.60 0.4483 154.90 0.6203 148.10 0.1019 150.40 0.1476 152.70 0.4574 155-00 0.6266 148.20 0.1043 150.50 0.1492 152.80 0.4663 Lovell-Sauerland and Associates August 23, 1996 Page 10 8/22/96 Lovell-Sanerland 6 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 <--DISCHARGE --- > STAGE <-DISCHARGE--> STAGE <--DI-SCH Rrc---> STAGE <--DISCHARGE --- > (ft) --- cfa--------- (ft) •96.60 --- cfs-- ------ (ft) --- cfs__ _______ (ft) ---cfs-- -_____ 95.00 0.0000 0.0589 98.20 0.0033 y: 99-00 0.4611 =iiaa�'• 95.10 0.0147 96.70 0.0607 98.30 O.D046 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 100.20 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 98.90 0.3022 100.50 0.5793 95.80 0.0417 97.40 0.0721 99.00 0.3282 100.60 0.5919 95.90 0.0442 97.50 0.0736 99.10 0.3518 100.70 0.6043 96.00 0.0466 97.60 0.0751 99.20 0.3736 100.80 0.6163 96.10 0.0488 97.70 0.0765 99.30 0.3939 100.90 0.6291 96.20 0.0510 97.80 0.0779 99.40 0.4131 101.00 0.6397 96.30 0.0531 97.90 0.0793 99.50 0.4312 96.40 0.0551 90.00 0.0807 99.60 0.4485 96.50 0.0570 98.10 0.0820 99.10 0.4651 8/22/96 Lovell-Sauerland 6 Associates Inc pa;c 11 --...........................................a_.......�... .....�. STAGE DISCHARGE TABLE RISER DISCHARGE ID No. RE 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 <-DISCHARGE --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGrt--- > _------- cfa- (ft) __ - --0.0000 _ (ft) --- cfs__ _______ (ft) ___cfs -- _______ (ft) ___cfs__ 154�00 154.20-�0.8711 154 5D i2.6743 � ,I54 80 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 154.10 3.1642 155_DO 3.7820 8/22/96 Lovell-Sauerland 6 Associates Inc pa)E 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 --- > STAGE <--DISCHARGE --- > STAGE <--DISCHARGE---> (ft) ---cfs--------- (ft) ---cfs--------- (ft) --- cfs-- ----- - Lovell-Saue<iend and Associates August 23, 1996 STAGE <--DISCHARGE --- > (ft) ---cfa--------- Page 11 S00'S06 O'0000 100.60 0.3080 _. 100.80 L1.6003w 201.00 2.6143 100.50 0.0000 100.70 0.8711 100.90 2.4638 101.00 2-6743 8/22/96 Lovell-Sauerland i Associates Inc page 13 LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <-------- DESCRIPTION --------- > (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) 10-YEAR KAIREZ ............... 0.40 0.72 PIPEK CTRLK 150.00 1 4064.24 100-YEAR KAIREZ .............. 0.921.23 PIPEK CTRLK 152.47 11 5752.99 10-YR NICHOLAS 0.90 PIPEN CTRLN 98.48 2 1915.09 100-YR NICHOLAS .............. - 0.61 PIPEN CTRLN 99.13 12 2363.08 1 y� f i 1 +"I too y Y UUE.) lxt nuM�C'c, 1Ir on -i �}hl5 L`` D�4wth n4J� IA(, C2 Lovell-SaueAand and AssocWw August 23, 1990 Page 12 DRAINAGE CALCULATIONS 23-Aug-96 DETENTION PIPE FOR KAIREZ PLACE 08:50 AM Y7a"1R1`yr1I94WA-= Estimate of required detention storage volume = 6000 d Assume a det pipearch 117.0 x 79.0 (width and height) Goss section area = 52.0 sf Usable vol. of Type I CS 6.0 s0ft = of Usable vN. of 2.0 Type 11 MH 54.0 inch dia = 2004 d Usable vol. of Type II MH 72.0 inch dia = d Usable vol. of 18.0 inch pipe: It long = of 5 Usable vol. of 36.0 inch pipe: 4.0 ft long = 28 3 d Required pipe volume = 5762.3 cubic feet Required pipe length = 110.8 linear feet (,+C Length of pipe used = 111.0 FT_ Storage provided = 6009.7 cubic feet Minimum grade elevations: ei- 02 (� Top DIS detention CB 156.19 with 2.50 It Overflow ctearance Top DIS detention CB 155.08 with 2.0 ft cover j' (i• \, 7 �,\ r . Top U/S detention CB 155.69 with 2.0 ft cover Inv Grind surf. elev = 147,09 (over arty inlet 0.5 ft above OF � Inv slay at U15 end = 1a7.06 Max water surface slay = 153.69 (detn. pipe sl. = 0 5D%) / Invert elevation = 146.5001 CALCULATION OF OUTLET SIZE ,kb �K ` i / 1 Y�✓ y" bu� Required release rate, orifice 1 = n 0 Required release rate, orifice 2= ` . 70 rr{"l / �Q J �• g Required release rate, onfice 3 - At elevation: H, It a, at d,6 d,inches prow. Y 146.50 6.63 150.50 2.03 Full storage - area, a=Odo/(.62 x(2 xg xh)".5) orifice diameter. d = (4/pi x a)".5 06 N `u !D N 2 y 04 0.015 0.14 0.033 0.21 i 100-YEAR TARGET o 10•YEAR TARGET c ob a 2 4 5 T -"z Detention Volume, cubic feet 1 - 11/16 0 2 - 12 4052 -0 ------------ ---- 6010 g = 32.2 V I Vs DRAINAGE CALCULATIONS DETENTION PIPE FOR NICHOLAS LANE 08.53 AM DETENTION PIPE SIZE Estimate of required detention storage volume = 2500 d Assume a det. pipe 72.0 inches, diameter Cross section area = 28.3 sf Usable Vol of Type I C8 6.0 sUR = d Usable Vol. of 2.0 Type II MH 54.0 inch dia = ' 90 9 d Usable vol. of Type II MH 72.0 inch din = d Usable vol. of 18.0 inch pipe: ft long - d Usable vol. of 36.0 inch pipe: 4.0 It long = 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 feel Minimum grade elevations: Top D/S detention CB 103.96 with 2 50 It 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 Gmd surf. elev = 101.96 (over any inlet 0 5 It above OF Inv elev at U/S end = 95.41 Max water surface elev = 101.46 (detn. pipe sl, = 0.50% ) Invert elevation - 95.00 CALCULATION OF OUTLET SIZE ��•�'r+`t'�1� r^ �, Required release rate, orifice 1 = 0.100 �� • rV ��•� f, Required release rate, orifice 2 = 0.350 Required release rate, orifice 3 = A. Storage At elevation: H. ft a, sf d,ft d,inches �, f pmvd. a l 95.00 6.05 0.006 0.10 1 - 3116 0 n•'� O 99.50 1.55 0.057 0.27 3- 114 1968 Q �" 0 Full storage = 2509 area, a s Odo 1(.62 z(2 x 9 z hr.6) y=32.2 o r orifice diameter, d - ( 410 x ar.5 r QL oK m os DL L41L4� Wk04 ` 0 � '0 100-YEAR TARGET a �� If 1 oz 01 1 Detention Volume, cubic feet VISTA DEL MAR, LSA 2926 23Aug-96 SCS Weighted average curve number calculations 08:54 AM SCS Hydrologic Soils type:-> C C EXISTING BASIN n1a Na 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: CN Undisturbed forest land 76 76 0 0 0 Second growth forest 81 87,000 81 87,000 Meadow or pasture 85 72,000 65 72,000 Grass, > 75% coverage 86 86 Dirt roadtparking lot 87 87 Gravel mad/parking lot 89 89 Grass, > 50% coverage 90 90 Orchard with crop cover 92 92 Cultivated land 94 94 Impervious 98 15,000 98 15,000 Existing onsde impervious = 13,9W Open water 1 D0 ------------ 100 Total Weighted CN for each basin. 841 76.0 76.0 84.1 ------------'-- Pervious: --- Area, acres: 3.65 0.00 0,00 3.65 Weighted CN: 82.8 76.0 76.0 82.8 Impervious: Area, acres: 0.34 0.34 Percent impervious area: 8.6% 8.6% Detention 1 Detention 2 bypass TOTAL Future conditions Total AC 2.71 1.02 027 3.99 Total sf. 118,000 44,250 11,750 174,000 Assumptions: CN: CN Undisturbed forest land 76 76 Second growth forest (@ 10% of grass) 81 4,818 81 0 0 4,818 Meadow or pasture 85 85 Grass, > 75% coverage 86 48.182 86 0 0 48,1a2 Dirt road/parking lots 87 87 Gravel road/parking lot 89 89 Grass, > 50% coverage 90 90 Orchard with crop cover 92 92 Cultivated land 94 94 Impervious 98 65,000 98 44,250 11,750 121,000 Other impervious 5.000 8,000 1.760 14.750 LF of road/sidewalk, plat road. 500 5W Avg. Width of road/sidewalk 30 ft LF of road/sidewalk, frontage. 200 250 450 Avg. Width of roadisidewalk 25 It No. of housesnots 8 6 2 16 House/lot impervious 5,000 sUlot 5,000 5,000 5,000 Open water 100 100 ----------------------- --- ------ ---- ---- Total Weighted CN for each basin: ------ --------------- g2.4 ------------ 98.0 98.0 -------------- 94.2 Pervious: Area, acres: 122 0.00 0.00 122 Weighted CN: 85.5 85.5 85.5 85.5 Impervious: Area, acres: 1.49 1.02 0.27 2.78 Percent impervious area: 55.1% 100.0% 100.0% 69.5%