The URL can be used to link to this page

27864 PE-1751 MIDILOME 1994, Aug Traffic Impact Reportli i 4 FR)(9(& TRANSMITTAL Date lo File Project r Subject As you requested ❑ For your approval ❑ pour information ❑ For your review ❑ Return requested ° From D EvANS ANC} ASSUCIAns, INN. ROFFSS1(?NAL SERVICES CONSULTING FIRM OFFICES IN OREGON, WASHINGTON, CAUFORNIA AND ARIZONA WEST 110 CATALDO SPOKANE, WASHINGTON 99201 (505) 327-8697 FAX (569) 327.7345 RECEIVED AUG 3 a 1994 SFGI°A14E COUNP ENGINEER Item Copies Date Descnpunn Traffic Impact Report Proposed Midilome East Development Spokane, Washington August 1994 Prepared for Midiiame, Inc. rr HUt-, L ' a~ ! r1 i ?Ft°i L~H' :',wPt3 _ y F . - 7~HrlC F , TABLE OF CONTENTS Page SLJNIM,~RY . . . iv INTRODUCTION . . . 1 CURIENT CONDITIONS 2 INTERSECTION &Nr) ROADWAY CONFIGURATIONS , , 2 State Road 27 2 32nd :Avenue . . 2 TRAFFIC PATTERNS 2 ~I J INTERSECTION OPERATIONS . . . . 2 Level of Service Criteria . . 2 Weekday AIM Peak I-lour 3 Weekday PM Peak Hour . . 3 BACKGROUND CONDITIONS 4 TRAFFIC VOLUMES . , . . . . 4 INTERSECTION OPERATIONS . , , , . . 4 Weekday AM Peak Hour . 4 VVeekday PM Peak Hour . , 4 PROJECT IMPACTS 5 DESCRIPTION OF SITE , . 5 SITE TRAFFIC . 5 Trip Generatiun 5 Trip Distribution . . . . 5 Trip Assignment 6 TOTAL TRAFFIC VOl U M ES 6 INTERSECTION OPERA,rit]`'S 6 Weekday AM Peak Hour 6 `Veekdav PNI Peak Hour . . . . . . . . . . . 6 RECOMMENDED IMPROVEMENTS , 7 IMPROVEMENT OPTION I . , , 7 IMPROVEMENT OPTION 2 . S IMPROVEMENT OPTION 3 , . . , . 8 CONCLUSIONS . . , , , . 9 Improvement Option i 10 Intersection Option G . . . . . . . . . . , . . 10 Intersection Option 3 . , 10 Recommendation , , to s AU(; c9 '?4 L36: ?w]Pf°i L)A% 'YAhiS RSS- k' F- "P FLAND P. r , LIST OF TABLES No. Title Page I, Summary of Intersection Operations iv 2. Vehicular Trip Generation 5 3. Comparison of Intersection Operations with Improvement Option 1 7 4. Comparison of Intersection Operations with Improvement Option 2 8 5. Comparison of Intersection Operations with Improvement Option 3 9 6. Proportion of PM Peak Hour Traffic Contributed by Midilome East Development . . . . 11 LIST OF FIGURES Follows No. Title Page 1. Vicinity Map . 2 2. 1993 Existing Conditions . . , , . 2 3. 1996 Background Conditions . . . 4 4. Project-Generated Traffic Distribution . , 6 5. Project-Generated Traffic Volumes . 6 6. 1996 Total Conditions . . . . 6 S l ?_1 06. !,':LPN CIP. i Pl-lPTLHKr I I TABLE OF CONTENTS (continued) P. -I Page APPENDICES APPENDIX A - Level of Service Definitions APPENDIX B - SR 27 and 32nd Avenue 3993 Intersection Counts APPENDIX C - Midilorne East Development Project Trip Generation APPENDIX D - Traffic Operations Backup Data Existing Intersection Configuration APPENDIX E - Traffic Operations Backup Data Improvement Option I APPENDIX F - Traffic Operations Backup Data Improvement Option 2 APPENDIX G - Traffic Operations Backup Data Improvement Option 3 APPENDIX H -"t"raffic Signal Warrant 'T'esting Improvement Option 3 ei 5UN"URY out assessment of the intersection of Sind Avenue and SR 27 indicates the proposed Midilome East Development would have an noticeable impact on the intersection operations. Although the future traffic operations could be improved by changing the stop-sign control, particularly with a four-way stop-sign control, stopping traffic on SR 27 is a concern for several reasons, including high travel speeds and rtaadway functionality. Therefore, a traffic signal is ultimately The best control for this intersection. While a traffic signal will also stop some traffic on SR 27. with proper signing, drivers approaching the intersection on SR 27 could be alerted to the upcoming signal so they will be prepared to stop, if needed. !Because the MUTCD traffic signal warrants are not met by the volumes projected for the 1996 condition with the Midilome East Development, the cost for adding this signal should be shared E? AS by bath the existing users and other future development. The proportionate cost of a S 150,000 traffic signal would be about S10,000 (6 to 7 percent) for Midilome East, The analysis for the 1993 existing, 1996 background. 1996 total, and. 1996 mitigated conditions is shown in the table below TABLE I Summary of Intersection (operations Current Stop~Sign Control Traffic Signal as on 32nd Avenue 'litigation Measure 1993 1996 i996 1996 1996 Intersection Existing Background 'fatal Background "T"otal 'weekday AU Peak Hour Eastbound LTfR C D D B S Westbound LTR C D E B B Northbound L A A A C C T'R A A A 8 B Southbound L A A A C C TR A A A B B Weekday P?Ff Peak Hour Eastbound LTR E F F B B Wastbound LT R E F F $ B Northbound L A A A C C TR A A A B B Southbound L A A A D D TR a A A B B iv INTRODUCTION The purpose of this report is to identify any improvements that may be necessary at the intersection of SR 27 and 32nd avenue due to the proposed Midilonte East Development. This analysis was requested by the Washington State Department of Transportation (WSDOT) to determine if the proposed Midilome East Development would trigger the need for a traffic signal. For the analysis, the proposed Midileme East Development, consisting of 127 single family residential units, was assumed to be fully occupied by the fall of 1996. An existing condition, based on 1993 traffic counts at the intersection, was examined. Background traffic volumes were projected for 1994 ?used on ata mutual growth rate and combined with projections for the proposed Midilome East Development, Weekday kNI and PM peak hour traffic was analyzed for all three of these conditions. This report contains discussions and summaries of all of the analyses performed and appendices contain the full analysis output. I is 9 "94 06 : IF1 f C9Fi~ fHf'r~ 9=0'='~~ n= Pi iPTLAHD CURRENT CONDITIONS P, Before determining the future intersection requirements, IDEA analyzed the existing intersection operations, INTERSECTION AND 'ROADWAY CONFIGURATIONS The intersection of SR 27 and 32nd Avenue is located on a state highway facility in the Spokane County, Washington, It lies in an area which is primarily residential, with most of the commercial development to the north. A vicinity map showing the intersection with respect to the proposed Midilorne East site and the surrounding street system is shown in figure 1. State Road 27 State Road 27 is a state facility running north and south through the City and County of Spokane. It connects with some of the major commercial corridors, and it has an interchange with Interstate 90. AT the intersection with 32nd Avenue, SR 27 is a three-lane roadway: one moving lane in each direction with a center turn lane. The speed limit is 50 miles per hour. 32nd Avenue 'Dirty-second Avenue is one of the only continuous east/west roadways running through a primarily residential area. It is two lanes wide, with one travel lane in each direction. At the intersection with SR 27, 32nd Avenue is controlled by stop signs, The speed limit is 35 miles per hour. TRAFFIC PATMRNS Current traffic volumes were measured in July of 1993. The weekday ANT and PM peak hour volumes are shown in Figure 2. The weekday PM peak hour is the period of highest activity. During both the AM and IFNI peak hours, the traffic volumes an 32nd Avenue are equal to or higher than those on SR 27, INTERSECTION OPERATIONS The Level of Service fLOS9 of each lane at the intersection was calculated for each of the peak hour conditions. The LOS for each time period is shown in Figure 2. Level of Service Criteria The Level of Service criteria at an unsignalized intersection in an urban area is defined in Appendix Table A-1. This table defines the Levey of Service concept with LOS A representing. 2 HUG '19-1 0-6: 21FIN E4~' . lHi I'~ Fay FO TF ral1D F. 10 14~ Legend )(§RO 44 Traffic Volume Not to Scald A Level of Service DAVID EVa1S AND AMOATB. Mc. 04 r- son N i 0 ~ oo --44 ~ t75 ~ 14 _ 32ad g ■ F-" Avenue 41 A 166 243 'o ;4 ■ Al Weekd2y AM Penh Four Traffic d I I A F--- C ■ 3'2,-, d ■ Avenue C ~s 1r C. W:ekda~ ::.I Peak Hour Op,;rattuns W. r- :n cz ~ I ■ -197 € - 71 30 153-~ 68 B. Wackday Pkl Peak Hour Traffic ~ r~ prp H I ■ - ■ .E I v D. Weekday PM Peak Hour Operations 32nd Avenue 3Znd ,-Avenue FIGURE 2 1993 EXISTING CONDITIONS F._ ik RO Not to Scala DAVID EVANS AYD ASSOCIATES. 111, 16th Ave. 32-md Ave. i \ i f SITE ~ 1 1 (ya I 1 t e dIS~ ~ Mica Rd. - 3 ~ Er Cr: FIGURE 1 VICINITY MAP AUG c'- '94 06-'-T-:PM N E','R i'; F+=ifs i LR iU P 11 a no delay condition and LDS F representing severe delay and congestion. Generally, LOS D, representing a moderately congested condition is the minimum standard to be maintained in an urban area. Weekday AIM Peak Hour During the weekday AIM peak hour, traffic is higher on 32nd Avenue. where it is controlled by stop signs, than it is on SR 27. The northbound and southbound approaches on SR 27 operate at LDS A, while the eastbound and westbound approaches on 32nd Avenue operate at LOS C. rte. Weekday PNf Peak- Hour Luring the weekday PM peak hour, traffic is fairly balanced on Sk 27 and 32nd Avenue. Traffic on SR 27 would operate at LDS A, while the eastbound and westbound approaches on 32nd Avenue would both operate at LOS E. 3 AUG .mJ QG :'-FI'1 W F.13 Legend 51 Traffic Volume Not co Scale A Level of Servr:e DAVID EVAK3 AND AMOCIAT°_S. INC W r- sn rr a ca 5 i ra +n I 24 4---203 228 V 16 39 _ 32nd 32nd Avenue ~ ~ Avenue 47 r 35 --J 192 -0 I i 177 ~ 23 -7 n 79 tr rn e ° A. Weekdsv AIM P•aak Hour Traff z B. Weekday PM Peak Hour Traffic cv i a 9 r D 32nd Avenue I]--. ■ d ~ E I C. Weekday AFL[ Peak Hour Opamcioos x r °-F ■ D. Weekday P%1 Peak Hour Operations 32nd Avenue FIGURE 3 BACKGROUND CONDITIONS ~AU-3 19 * 94 96: cEPM C1$~ E' °Hr r~ H S'Sl.n_ F- RI LPrrt, F. 1 BACKGROUND CONDITIONS The background condir;ons were evaitiated for the year 1996 without the proposed Midliorne East Development. TRAFFIC VOLUMES Background traffic volumes were estimated for the year 1996 by applying an average annual growth rate to ail of the traffic volumes at the intersection, To calculate this annual growth rate, _ average daily traffic volumes on SR 27 were compared for the years 1988 and 1992. During that four-year time period, traffic on the highway grew by an average of 5 percent per year. This growth rate was applied to both the SR 27 and 32nd Avenue traffic volumes because there is no available information on 32nd Avenue. Tice estimated background traffic volumes for the weekday AIM and PM peak hours are shown in Figure 3 INMRSECTION OPERATIONS The Lavel of Service {-LOS} of each lane at the intersection was calculated for }ach of the peak hour conditions. The LOS for each 'ime period is shown in Figure 3. Weekday ANL I Peak Hour During the weekday AM pear hour, operations would worsen on :32nd Avenue. While traffic movements on SR 27 would continue to operate at LOS A. both the ea,;tbcund and westbound approaches on 32nd Avenue would =operate at LOS D. Weekday PM Peak Hoar Traffic operations on 32nd Avenue wouid also worsen during the weekday PM peak hour Traffic movements on SR 27 would operate at LOS A. On 32nd Avenue, tooth the vastbeund and westbound approaches would oaf orate at LOS F. a condition indicating inadequate capacity and long delays. 4 hut: 2'~ 194 vJb' 23P~i 1,P, P. 14 PROJECT IMPACTS To evaluate the impacts of the proposed Midilome East Development. project-,generated trips were estimated, distributed on the surrounding street system, and added to the 1996background traffic. DESCRIPTION OF SITE The proposed Midilome East Development would consist of 127 single family detached _ residences located on a 44.7 acre site. Tlie proposed development would have rwo access points ucr off of 32nd Avenue between Madison Road and SR 27. SITE TRAFFIC Trip Generation The vehicular traffic generated by the proposed Midilome East Development was calculated using rates from the institute of Transportation Engineers' Trip Generation Report, 5th edition. 'T'able 2 summarizes the 24-hour and peak hour traffic volumes calculated using the equations from this report. TABLE 2 Vehicular Trip Generation Time Period Inbound Outbound Total AM Peak Hour 26 73 99 PIN4 Peak Hour 87 47 134 Weakday 24-Hour 643 643 1,286 Source; Institute of T'r3aspottat:on Engineers' 7'rtp C;errcreuron Report, 5th edition The proposed Midilome East Development is expected to generated 1,286 trips on a weekday, with 99 trips during the ANI peak hour and 134 trips during the PM peak hour. 5 OUR; -79 '94 06.22RI DP, %,'AFIS AESOC PCjP'LAI-ID F. 16 Legend 40 % Inbound Not to Scale 40-v Outbound DAVID EVANS AND A3SUCIVE. IVC. E lfith Ave. 1 ~ ti I ~ I I i g 5% ~k 5 Ct 3?ae. A% e. i 73 `a ! 40 % 60 40 % 35&a 4-:0% 3U ro ' 4951,---i SITE 1 s I Dishman -4 r ri -Mica Rd. FIGURE 4 PROJECT-GENERATED TRAFFIC DISTRIBUTION AUG 9 '94 06. _23P111 11H E';PNS P.)Ft? RID ~ - F. ic-- Trip Distribution The trip distribution for the proposed project was based on an examination of the overall transportation system in the area and the traffic volumes at the intersection of 32nd Avenue and SR 27. Most of the traffic on 32nd Avenue (75 percent) is traveling eastbound or westbound, with 20 percent turning northward and 5 percent turning southward. Volumes traveling eastbound and westbound were split approximately 50 percent in each direction. Based on these characteristics, the project-generated traffic distribution pattern was developed, as shown in Figure 4. a Trip Assignment u!~ Using the trip generation and distribution patterns, the traffic generated by the proposed Midilome East Development was estimated for the intersection of 32nd Avenue and SR 2T The project-generated traffic volumes are shown in Figure 5. TOTAL TRAFFIC VOLUMES Total traffic volumes were estimated for the vear 1996 by adding the proposed project-generated traffic to the estimated background traffic. T'hese traffic volumes are shown in Figure 6 for the weekday AM and PM peak hours. INTERSECTION OPERATIONS The bevel of Service (LOS) of each lane at the intersection was calculated for each of the peak hour conditions. The LOS for each time period is shown in Figure 6. Weekday Aivf Peak Hour During the weekday AIM peak (tour, operations would worsen from the background condition. The traffic movements on SR 27 would continue to operate at LDS A, while the eastbound approach on 32nd Avenue would operate at LOS E. and the westbound approach would operate at LOS D. Weekday PP4I Peak Hour Traffic operations on 32nd Avenue would also worsen during the weekday P:v1 peak hour. On SR 27, traffic movements would operate at LOS A, whale bath the eastbound and westbound approaches on 32nd Avenge would operate at LOS E. 6 AQ'; 29 "34 R-6.'44PM W', !/PrI'_ _ AS'.;O POs=TLAND P 121 Legend 51 Traffic Voincne A Level of Service Not to Seale er cl7 N ■ rs 51. 163 T 32nd W Avenue •1 7,, 59 221 27 Q tP ■ A. Weekday AIM Peak Flour Traffic x r.. E 2 f c 3 r 32nd I.._ A ertue d < x n r ■ F-~ ■ d I C. Weekday kM Peak Hour rpera:tocu D. W cekday PM Peak Hour Operations 32nd Avenue FIGURE b 1996 TOTAL CONDITIONS 0 DAVID EVA13 AND ASSOCIATZE, M qC V7 N e+'a G3 n r1 L~ 24 263 L* 55 32nd ` t 42 Avenue E~ 196 10 81~ B, Wpekdav PM Peak Hour Traffic AUG c? "a-• 06.24F[1 !JA'v Ys}-. N'3 P.17 Legend C=60 4 Traffic Volume Not to Scale DAVID EVANS ASO ASSOCIATES. INC. x re- ;n J f A 7 0 0 1 x-10 32nd ■ --t+ Avenue 11 i 29 _ i A. Weekday AIM Peak Hour Traffic x n V7 ~ r1 0 i I 4 35 I 0 32nd Avenlie 19 ' ~ f ~ f .q, Weekday PNi Peak Hour Traffic FIGURE J PROJECT-GENERATED TRAFFIC VOLUMES rAnS u ~ ~,vF ft_ htl P. 1 14JG 219 1 ob c~pr'1 DA'. 1ECONLVIE, NDED 1IMP OVENEENTS Intersection operations are expected to worsen with the proposed Midilome East development. On 32nd Avenue, both the eastbound and westbound approaches would operate at LOS F during the PM peals hour. Twee options were investigated to improve the future operations of this intersection. IMPROVEMENT OPTION I The first improvement option would be to change the intersection control so that the northbound r"may and southbound movements on SR 27 would be controlled by stop signs while the eastbound and westbound movements can 32nd Avenue would be uncontrolled. Rased purely on a review of traffic volumes, this intersection control is more logical because the volumes on 32nd Avenue are generally equal to or higher than those on SR. 77. Table 3 compares the background and total traffic operations with the stop-sign control on 32nd Avenue, as it currently is, and with the stop-sign control on Sit 2°1. 'T'ABLE 3 Comparison of Intersection Operations with Improvement Option A Stop-Sign Control on 32nd Avenue Slop-Sign Control on SR 27 Intersection Background Total Background Total Weekday AM Peak [Four Butbound LTR D D A A Wcsthound LTR D E A A Northbound L A A C TR A A B Southbound L A A C C TR A A A A Weekday PM Peak Dour Eastbound LTR F F A A Westbound LTR F F A A Northbound L A A D E TR A A S B Southbound L A A D D TR A A C D Overall, the intersection would operate better with the ,stop-sign control on SR 27 than it would, on 32nd Avenue. The northbound left turn would operate at LOS E during the peak hour. However, because the number of northbound left-earning vehicle s-(Z•-is-Mica oiler than the combined number of eastbound (319) and westbound ( h>~ Sie~r; ,coon would operate better overall. AUG 3 0 1994 7 SPOKANE 00"120 EiIGMEER P~ul_ 29 194 (36. _:5:011 EIA4 r•~a 31 ASS, Pr.,PTLAND P 20 The primary concern with Improvement Option 1 would be stopping vehicles on 5R 27. This state facility has a speed limit of 58 miles per hour. Although is frequently carries a lower volume than 32nd Avenue, SR 27 is a major transportation facility connecting residential areas to Interstate 90 and sonic major commercial areas. IMPROVEN ENT OPTION 2 The second improverent option would be to change the intersection control so that the bath 32nd Avenue and SR 27 would be controlled by stop signs, The four-way stop-sign control would distribute delays onto both roadways more evenly, as shown in Table 4. TABLE 4 Comparison of Intersection Operations with Improvement Option 2 Stop-sign Control on 32nd Avenue Four-way Step-Sign Control Intersection Background Total ftckground Total Weekday AM 2'eak Hour Eastbound LTR D D A a Westbound LTR D E B S Northbound L A A A A TR A A A .A Southbound L A A A A TR A A A A Weekday PM Peak ffour Eastbound LTR x l= B E Westbound LTR F F 8 B Northbound L A A A A TR A A A A Southbound L A A 'B S TR A A B B With the four-way stop-sign control, all of the approaches wculd operate at LOS A or B, with no one movement experiencing substantially more delay than any other movement, As with Improvement Option 1, a major concern with Improvement Option 2 iS stopping vehicles on SR 27. INIPROVEN ENT OPTION 3 The third improvement options would be to change the intersection control to a traffic signal. Although the analysis of traffic operations with the stop-sign control indicate that the intersection would operate at or near a failure condition during peak hours, the projected total traffic volumes would not meet the traffic signal warrants contained in the Manual of Uniform Traffic 8 qUG 29 ;4 e6 -'25PN 11~ E, AHS P1)PTL-iND P. -I 1 Control Devices tM'UTCD). However, because of the concerns about stopping traffic on SR 27. this option was analyzed as well. For the analysis of the SR 27132nd Avenue intersection with a traffic signal, three assumptions were made: 1) the traffic signal would be fully actuated. 2) the northbound and southbound left- turn movements would have a protected phase, and 3) the total cycle length would be 60 seconds. The results of the analysis are shown in Figure S. TABLES Comparison of Intersection Operations with Improvement Option 3 Stop-Sign Control on Traffic Signal ~1~.JL~J 32nd Avenue Background - Total Intersection Background Total VIC LOS V/C LOS Weekday AM Peak Four - - Sastbound LTR D D 0.44 B 0.49 B Westbound LTR D B 0.44 B 0.42 B Northbound L A A 4.44 C 0.49 C TR A A 0.44 B 0.49 B Southt=nd L A A 0 22 C 0.24 C `S'R A A 0.27 B 0.31 B Weekday AVY Peak Hour Eastbound LTIR F F 0.52 B 17.56 S Westbound LT1R F F 0.55 H 0.59 B Northbound L A A 0 39 C 0.46 C TR A A 0.31 B 0.31 B Southbound L A A 0.55 D 0.59 D TR A N 0 55 13 0.59 B With a traffic signal. 211 traffic movements would operate at LOS 3 with the exception of the northbound and southbound left-turn moveaneuts, which would operate at LOS C or D. (Level of Service definitions for a signalized intersection are contained in Appendix Table A-2.) This improvement option would also requiring stopping vehicles ❑n SR 27. However, fewer vehicles would be stopped because many would arrive during the green-light phase of the signal cycle. CONCLUSIONS To minimize delays that are expected to occur an 32nd avenue, some change in traffic control would be necessary. 9 F'. PUG CG:26P11 iF 1;'JF;H ASS-Di- POFTLP1I1- Improvement Option Y Changing the stop-sign control from 32nd Avenue to SR 27 would make sense based purely on the traffic volumes. which are frequently higher on 32nd Avenue; but, supping traffic on 5R 27 is a major concern. This state facility has a speed limit of 50 miles per hour, and it provides access to Interstate 90 and some major commercial areas. Intersection Option 2 A four-way stop control would offer the best overall intersection operations with all movements operating at LOS A or B. However, stopping traffic on SR 27 is also a major concern for this alternative, Intersection Caption 3 Although traffic operations would improve with a traffic signal at this location, the projected traffic volumes do not meet the lv UTCD warrants for signalizing an intersection. This option would also stop traffic on SR 27 at times, but not all of the traffic would be forced to stop for the traffic signal. With proper signing, drivers approaching the intersection on 5R 27 could be alerted to the upcoming signal so they will be prepared to stop. Recommendation Although the future traffic operations could be improved by changing the stop-sign control, particularly with a four-way stop-sign control, stopping traffic on SR 27 is a concern for several reasons, including high travel speeds and roadway functionality Therefore, a traffic signal is ultimately the best control for this intersection. Because the Iv1UTCD traffic signal warrants are not met by the volumes projected for the 1996 condition with the Miditome Bast Development, the cost for adding this signal should be shared by both the existing users and other future development. Table 6 shows the calculation for estimating the proportion of traffic at the intersection that would be traveling to and from the Mid11orne East Development. Based an these calculations, the proportionate cost of a 5150.000 traffic signal would by about $10,000 (6 to 7 percent) for Midilome East. to "?4 OE : -ZE PM Ni =tiJ r;rr ra _ . ~ rLs~r f E~ TABLE 6 Proportion of Ptii Peak Hour Traffic Contributed by Midilome East Development Approach Background Midilome East TOW Trufric Contribution Trafric 32nd Avenue Eastbound 291 28 319 Westbound 311 35 346 5R 27 Northbound 214 4 218 Southbound 365 13 378 Taal 11181 so 1,261 x erccnt Contnbution 93.66 % 6.34 7 10000 17a .V 11 R.:"? OFFICE OF TBE COUNTY ENGINEER SPOKANE COUNTY, WASHINGTON TO: Jeff Forry, Department of Buildings FROM: Bill Hemmings DATE: Monday, April 15, 1996 SUBJECT: B.C.C. resolution # 91-0882 Implementation (JULY 2, 1991) Attached are the individual lot plans for each lot containing a Swale in MIDILOME EAST 1ST ADD, plat# P-1751. Please give the appropriate lot plan to the individual applying for a building permit on the lot, so they can draw their house and approach to scale on the lot. We will need this plan, and the corresponding $1000.00 cash surety, in the form of cash, letter of credit, or savings assignment, before we can issue the approach permit. Also attached are the letter of credit and savings assignment forms. k\dlf1208pri 2/96 "SAMPLE LETTER OF_ CREDIT" „ (USE BANK LETTERHEAD) „ (BANK NAME ADDRESS ZIP CODE PHONE # AND OTHER INFORMATION) IRREVOCABLE LETTER OF CREDIT AMOUNT: $ 1,000.00 NO. BENEFICIARY: SPOKANE COUNTY ENGINEERS 1026 W BROADWAY SPOKANE, WA 99260-0170 SUBJECT- LOT _ BLOCK MIDILOME EAST 1ST ADD (Plat) PLAT # P 1751 . (Development) Gentlemen: We hereby authorize our irrevocable Letter of Credit in your favor, and authorize you to draw on the (bank), a draft up to one thousand (Dollars) ($1,000.00), for the account of {developer). The draft, drawn under this Letter of Credit, covers the assurance of completion of installation of storm drainage, drainage swales, sod and other work as is incidental and related thereto in accordance with the drawings and specifications as submitted to and approved by the Spokane County Engineer's Office on (date), and is to be accompanied by the following documents' written request by Spokane County Engineer's Office to (bank), at the above address indicating non-completion of all or any of the above improvements and that amount of money required to complete such improvements. We hereby agree with the drawer, endorser and bona fide holder of this draft, negotiated under and in compliance with the terms of this credit, that said draft shall be duly honored upon presentation at the (bank), at any time before completion of the above-described improvements or performance, in which event written notice shall be given by Spokane County to the bank. (developer) shall be responsible for any cost incurred by the county in excess of the amount of security. Drafts, drawn under this Letter of Credit, shall bear on their face the words Drawn under (bank) (bank address) Credit No. Dated Bank Name• By: (authorized signor) kldlf1208pri 2196 "AGREEMENT" In consideration of the issuance of a building permit for Lot , Block , MIDILOME EAST 1ST ADD (plat) plat # P 1751 (Developer) has deposited $1,000.00 with Spokane County as security for full and faithful performance by Developer respecting certain drainage facilities and sod in accordance with the drawings and specifications as submitted to and approved by the Spokane County Engineers Office on (date) 199_. Developer hereby agrees that should such drainage facilities and sod not be constructed in accordance with the approved drawings within six months of occupancy, Spokane County may then use the security to bring these facilities and sod into conformance therewith. Developer shall be responsible for any costs incurred by the county in excess of the amount of security. Spokane County agrees to return to Developer any unused funds upon satisfactory completion of these facilities and sod. NAME & ADDRESS TO BE RETURNED T4: (Developer Signature) DATE kldlf1208pri 2/96 6& impson Engineers, Inc. CIVIL ENGINEERS AND LAND SURVEYORS FOUNDED 1946 Licenced in Washington and Idaho N. 909 Argonne Road Spokane, WA 99212 (509) 926-1322 Fax: 926-1323 December 29, 1998 Doug Busko, P.E. Spokane County Engineers 1026 W. Broadway Avenue Spokane, WA 992+60 Subject: Midilome East 1' Addition Dear Doug, CLARENCE E SIMPSON 1991-1987 RICHARD L. SIMPSON CHARLES E. SIMPSON On December 29, 1998, you called me and mentioned that the home builder at Lot 1, Block 6 of Midilome East 1' Addition had poured his house foundation considerably higher than the adjacent curb, and feels he may have difficulty in constructing the driveway as specified in the street and drainage plans for this plat. The drainage plans specify that the driveway should slope downward from the curb gutter to an angle point in the driveway and then back up towards the house. This allows stormwater in the stmt to flow into the drainage Swale. You mentioned that as an option, the home builder was proposing to construct a culvert under the driveway This option would allow stormwater in the swale to flow under the driveway, but would not allow water to flow into the driveway cut as planned However, it appears that the existing curb cut at Station 9+50 of 35"` Avenue (low point) would be capable of handling all the stormwater frorn tins basin (35'h Avenue and Woodlawn Street) in the event that the driveway to- Lot 1, Block 6 is revised and is unable to accept stormwater. I am sending copies of the preliminary drainage plans and calculations for the next phase of this subdivision, Middome East 2nd Addition. I hope this information will be of help to you and the home builder in finding a solution. Please call me if you have any questions. Sincerely, Kevin W. McMulkin, RE r r' r r ■ w r r N M N STORMWAFER DRAINAGE REPORT and Roadway Design MAD[LONE EAST 2nd ADDITION October ?3, 1998 Prepared by- Simpson Engineers, Inc . North 909 Argonne Road Spokane, Washington 99212 The design nnproveme= shorn 'in this set of plans conform to the applicable editions of the Spokane County standards for road and sewer construction and Spokane County guidelines for stormwater management- All design deviations have been approved by the Spokane County Engineer. I approve these plans for construction TABLE OF CONTENTS I. Drainage Summary L1. Typical Curb Inlet and Driveway Cut Calculations (additional calculations with Basins) * Stormwater Drainage Calculations for Midilome East 2nd Addition: Basins A through M. LII. Attachments: S.C.S. soils map, and soil description * Roadway Surfacing Des= SWht Distance Analyses aln(j Maps for Vercler Dn,,re_ 35th Avenue. and ,oth Al e nlue v 4 Stormwater Drainage Report: Midilome East 2nd Addition DRAINAGE SAY: This project is located south of 32nd Avenue and east of Pines Road. The peat proposes 37 residential lots totaling approximately 17 acres. The development is divided into thirteen (13) basins, A through. M. See Drainage Map for Miidilorne East 2nd Addition. Each basin is composed of two subareas; 1) grass lawns and swales, and 2) impervious roofs, driveways, and asphalt paved streets. Storimwater flows overland across roofs, grass lawns, and driveways and into grass swales behind the street curbs. 5torrnwater from asphalt streets flows along the curb gutters and into the grass swales through driveway curb cuts and curb openings located at low paints in the curb profile. As specified in the "Guidelines for Stormwater Management", page 5-=4; where a sloping Swale is less than 100 feet long, and slopes 1% or less, the swale may be considered flat. Driveways along the road will obstruct the swales, creating a series of individual swales that are less than 100 feet long and less than 1.0%, and 6 inches deep between the driveways. Therefore, each Swale will be considered as flat. Stormwater will fill each Swale to a 6 inch depth and then overflow across each driveway until the water reaches the final Swale and drywell(s). 01 The grass swales were calculated to hold the first 112" of rainfall runoff over the asphalt street areas. Figure 2, page 6-3, of the "Guidelines for Stormwater Management", by Spokane County Engineers, was used NJ for rainfall intensity and duration occurring at a 10-year storm frequency. _ The Rational and Bowstring Methods were used to calculate the peak storrnwater runoff for each basin, and the type and number of drywells needed for each basin based on the storage capacity of the Swale In accordance with "Soil Survey, Spokane County, Washington", 1968, the soils at the site are categorized as: Garrison very gravelly loam,... similar to 'Garrison gravelly loam, except that the surface layer is Gm$, 5' grvery gravelly. SxB Springdale graveily sandy loam, deep,... similar to Springdale gravelly loam, except that the depth to gravel and coarse sand is more than 36 inches. These types of 5ac1 are considered acceptable for drywell installation per Section 4-4.1 of "Guidelines for ■ Stormwater Management". Stormwater Drainage Report: MiidHome East 2nd Addition CURB INLET AND DRIVEWAY CUT CALCULATIONS: 1) For each basin, calculations have been made for the curb inlet located at a low point. Each curb inlet located at a low point is sized to accept the flow of stormwater from the contributing pavement subbasin. 2) In some cases, additional curb inlets are required on continuous grades. For example, additional curb inlets will intercept the stormwater on continuous grades along Vercler Drive. Runoff calculations have been made for the pavement area in these subbasins. 3) Driveway cuts on continuous grades will intercept the stormwater flow in each pavement subbasin prior to the curb inlet at the low point. A typical calculation has been made for a driveway cut for the pavement in subbasin H4, since this subbasin has the largest pavement area of any subbasin in the plat, it will have the largest peak flow of any subbasin. A driveway cut of 11.35 feet is required for this subbasin, but is less than the typical driveway cut of 24 feet. Since, the runoff will be less in all other pavement subbasins, driveway cuts for the other subbasins will be sufficiently wide (24 ft.) to intercept the stormwater in the corresponding subbasins. Driveway Opening on Continuous Grade, Example: Subbasin H4 a = 0 in. Flowline depression at opening y = 0.08 ft. Depth of flow in normal gutter Q = 0.21 cfs Design discharge Qa/La = 0.0185 From Fig 16(a), page 6-39 "Spokane County Guidelines for Stormwater Management" L = Q/(Qa/La) = 0.21/0.0185 = 11.35 ft. Driveway Opening; 24 ft. wide, 6 in. deep OKAY I r Date: MW8 Design: kwm Disk Re: Al Va=naA1M12838jds Basin Name: "114" Project Name: Midilome East 2nd Addition Project Number. 12838 r Site Location: N 12. S. 34, T. 25 N., R. 44 E. W.M. Basin Description: Point of Concentration: SUBAREAS. Description Acres C KC Pavement RATIONAL FORMULA HYDROLOGY O DRAINAGE BASIN ANALYSIS for 10 YEAR STORM EVENT 0.072 0.90 0.065 Total Basin Area, acres = 0.072 Composite Runoff Coefficient = 0.900 Combined (Area' Runoff Coefficient) = 0.065 TIME OF CONCENTRATION (minutes): Tic (overland Row) Tc (gutter flow) Ct = 0.15 L2 = 155 Z1 = 36 L1 (A) = 18 Z2 = 0.167 N(A) = 0.016 B = 0 S(A) = 0.0278 n = 0.016 S = 0.0184 Tc (A) = 0.21 d = 0.087 L1(B) = 0 Tc (gut.) 1.69 N(B) = 0 Tc(A+B) : 0.21 S(B) = 0 Tc total 5.00 Intensity: 3.18 Tc (B) = 0.0 Holding 5.52 0 (estimated ® d) = 0.21 c.f.s. Time of Concentration = 5.00 minutes H4 Virginia Road Driveway Intensity-Duration for 10-year Storm Event Time Time Intensity Incrmnt. Incrmrit. (min.) (sec.) (inJhr) (411co1 5.00 300.00 3.18 5 300 3.18 10 600 224 15 900 1.77 20 1200 1.45 25 1500 1.21 30 1800 1.04 35 2100 0.91 40 2400 0.82 45 2700 0.74 50 3000 0.68 55 3300 0.64 60 3600 0.61 65 3900 0.60 70 4200 0.58 75 4500 0.56 80 4800 0.53 85 5100 0.52 90 5400 0.50 95 5700 0.49 100 6000 0.48 PEAK DISCHARGE, 10 YEAR STORM: Q=C'I•A= 0.21 C.F.S. DEPTH: OF FLO - y =FEET ` .01 .02 .03 .04 03 .06 .08 .10 .2 .3 ■ I T- I I I I I I I, I I I I I I I ° I I. ! I I I 4 I I 1 -L ' ~ - +,7, ' I ~ I 1 I i ! ~ ~ L I I I I ~ I I ~ -i ! I I I I I I I T~ 7- I. I ~ i I I 1 1 1 1 1 1! 1 I~ I I I I I I ~ t l~ I I ~ I ~L I I I I I I I I ! I I I I I ~ I I~~ I~ I I I I I I I I T I I I I rl I I I I °t +Y I IIII 11~ I~~~ I 1 1 1 1 1 1 1 I ~I I I IIII I ~ I I I I I ~~5 I a I ' 1 • ~ I I I I I 'ti 1 1 I I ° ( i I I I I I ' ~ I . I r ' I I ' -L I I ~ T y- ~ ~ I I I I I I ( t I i ~ I II I I ~~T I I I i I I I I" I I I I I IIII I I I I I I I IIII I I I. j~j i I I I I IIII I I I I I I I --f~- {1. I I I I I I ( I I I I I I I I I I I I I I I I I I (a) DISCHARGE PER FOOT OF LENGTH OF CURB OPENING INLETS WHEN INTERCEPTING 1000110 OF GUTTER FLOW (b) PARTIAL INTERCEPTION RATIC FOR INLETS OF LENGTH LESS THAN La I I I I Q/ I ' 7 o- L I I I I i I~ i ~ I TS I I ~ I I I / I I I I I I I I j i I I i ~ I I I I I I I I I I I I .6 .s .4 .3 .2 Qa La .10 .08 .06 .0S .04 .03 .02 0185 .01 1.0 .8 .6 .s Q 3 Q G .z .10 07 .06 .08 .10 z -3 .4 .5 .6 .3 1.0 L/La CAPACITY OF CURB OPENING INLETS ON CONTINUOUS GRADE 6-39 FIGURE 16 4 .S .6 .T .8 .9 1.0 1.0 I I 1 .s I M1D11_OME BAST 2~D AVDITIoN DFLA1NAGE CALCULATIONS a a e $PAs1N %G" I ~Z$38 5 (26(9g KW M 0 3Zo Z /AREA _ ~ ~ i o, 9256 acre oT AL A PAlt T Z ('355~~ ~18) Z 6,380 f+z 35TH AVENUE (Z14!~ (7-0 = 5~48D S t.'- WOOD LAWN DROVE l S-10 .z -v 0.2.-125 acr c A ~Rt-4 6s - 3 Dr~v~s 1,000+t _ 31000 T0.0689 Acre Dr~'je. t z r a A RooFS ` i Roos Z~ODO z 31000 t}• 0,0689 aCV•t: IA ltATsv.vtou5 z 11119-1a + 31000 t 3100 11 0 ft.'' 0.3392 ache P C,?-ASS _ `~01 3zo - 11 t$1 O = ZZ~45 O -f~ 0.51 5 acre STb(ZAGE gEQV1FZEp ; N zo9. _~or0.9e (11,~~1o fez) t~z is. Z 495 r{3 1 ~ to Ez. 3 b) Bows}~`'~j = 211 + 1 'Dou~tL Borre.l Drywelk (cxisiiv\g) (1,0 t;s °u+) 5TOTAG15 QR0V10ED -7 16r ~T7 > 2~ ~ GI J J Gz G3 G,5 ~G MxD 1LotAS EAST 2"D ADD IT Iv N 5 ~26 (98 D(ZAINAGE CALCULATIONS PA"1 EMEN° fiRsA ki ? O s4 ` STotzAG E REQWIZ Ev S WALE S't DRAG E AVAILABLE o f ~.z o f f3 , a i l T• ) ~'io')(18) = I~Z6o f}'' 53 fk3 (3o`,(t•98 FTZ~ 59 3 f-, ~5'} (13') - ql L rT ~ 41 3 ft. ~72~~t•`1~ FT-'-)- l4-2 ? FT, ~1o5')(Ig) ~ \~gqo ~6G) (x•98 FT z~ ti \3o FT 3 (lo') (zo*) - t,4Oo 0.0% mutt (39')(Z.62- too f-r? (95') ~Z~) = IMOD 3 4 1 F T 3 x,45$ ~tL 311• f-t a (S5') (zo'~ = 1,100 Ri. (90) (1.34 F't l~ T. 120 fT.3 C24,~(ZO z a0 ~~Z Zo 3 C6i~) C1.34 fl.7 e 81 FT.3 11,8"10 496 fT3 to DkL.OME EAST Z~0 MDVTtON DKa%rIAGS CALCULATIONS. M838 Top of drive \?I I -Z. oo"° 1 .71 ~00 IL A ` l q - r. - - - L Swale Bob{pY,~ Zronc--C\+rb - 1O 10. G_ross_- Sec'ttovAo,1_r\Yea oT Swale -G.ZS 6.25 ~ ---•'6.5 ~ .1-. = - - I_...-..----•-- = ~ ~o.s~l- -Z.6g' 1 -t- `l/o.s~ (z:~-a~ L--x•34. ~~z - ---o-• 2L6. 2.Gg - - -`-~---•--L -211•- R ! Flo 42, .25t Top• of driveway _ rZ.O0,g ---__----t- C 411 1 L Swa\e_ So-itom Cov%c. ~urb _ `2~ 8, - - a~na S►aewalk 5.2s' 5.25 1 X0.5 --~GSS_SEL~IDVIA~ ~s -777Z- - T -r - A• -I:~) '...,v - - ~Z~~o,S)~Z•' -'s_[°-5~(3) _z{Z~ (0.5')(z•ZS ~ - y s 1 p ai'JLSw"1-•T.:JS8`cTl1"G~'Ld~~ :'i[rti_'rr.74a ~.A..:C'3~F+.'Y~.. C~CS•.G5 _ a r,4 . M\Dk\-OME 'SAST 2ND AVDtTIWA • MS3S DRA~NRGE CALC-U ~AT1oNs F- IW I3` ~aS~rnEV~"t I I~ Tod of ~`riv Way - - - _ y fill; SIC Z- N~.IIlo1 FT./FT. S (~1- -ur~,~l Swale..SIoPe Norm _ '~-Cert. Curb Swale. pottovn --10'__-- _ ~.4.-- CroS:-_Sec-Tlov\al..Areo, .af_.S~rvale....._ t.5 ~~:~~o:s~~`~.2~~ +"~-z~~0.5~~3.G4~- 1.`~$ FTz 4.29~13_GS / l-01 0.91 F 13 E o.S e- ynn e.v~T . -7 - - ToP of Driveway ' - - - - - - - - ;p o, o l 6'1 t=-T. I FT. I L "Vil ormal c / T.._ -'j-1 Coinc. -wale Slope Swale. Bozzon,~ C.vr~ • I . - - i - f , r 1,60 V n C . ~ FTC , l'b _ 3 cc c 1. :+5~'w'•.fls'+;"-~'~w~-Y'~r'~~. .~.tiF'?~~wniL~`~•~t'V.~.. 7~,tyt'~`~'F', K`.~"°Y'1 1n~_!S'~~+~'~ti~''`-t~'+'6'- -.•i••; ..•z,-5:. .>`v V r DETENTION BASIN DESIGN: RATIONAL FORMULA HYDROLOGY & BOWSTRING METHOD DRAINAGE BASIN ANALYSIS for 10 YEAR STORM EVENT Dale: 821198 Jab No.: 12838 Designer. K MCMULKIN Disk Dir.: A11itmstring Filename: 1283BAs For Tomlinson SUBAREAS Project Name: Mid'lome East 2nd Addition Project Location: N 12, S. 34, T. 25 N.. R. 44 E. W.M: Drainage Basin Name: Drainage Basin Oescription: 208' Ponding Area Name: Ponding Area Location: Poirt of Concentration: Description Aces C A'C Impervious '208'Amo Asphalt Pavement 0273 0.90 0245 Roofs 0.069 0.90 0.082 Driveways 0.069 0.90 0.062 Grass Lawn 0.515 0.15 0.077 Total Basin Area, acres - 0.926 Composite Runoff Coefflcierrt = 0.48 Combined (Area • Runoff Coeflictent) - 0.447 '208' DRAINAGE PARAMETERS "2W Pavement Area - 11870 sq. fL 208' Volume Provided - 713 cu. R at 6' depth Storm Storage Provided = 713 cu. R at 8' depth BOWSTRING CALCULATIONS Time Time Intensity 0 dev. V In vow Storage mean, (mm) IrIc mf t. nAw ( (CIS) (w. R) (CU. R) (cu. R) m '601 . -5.00 M 3.i8 ~'312 571 5 10 300 600 3.18 224 1.42 1.00 wi 702 JAW 600 271 102 15 900 1.77 0.79 792 900 -108 20 1200 1.45 0.65 843 1200 357 25 1500 121 0.54 868 1500 334 30 1800 1.04 0.48 883 1800 -917 35 2100 0191 0.41 895 2100 -1205 40 2400 0.82 0.37 916 2400 -1484 45 2700 0.74 0.33 926 2700 -1774 50 3000 0.68 0.30 942 3000 -2058 55 3300 0.64 029 972 3300 -2328 60 36W 0.61 027 1008 3600 -2592 65 3900 0.60 027 1072 3900 -2828 70 4200 0.58 026 1114 4200 3086 75 4500 0.56 025 1151 4500 -3349 80 4600 0S3 024 1160 4800 3840 85 5100 0.52 023 1208 5100 -3892 90 5400 0.50 022 1229 5400 -4171 95 5700 0.49 0.22 1270 5700 -4430 100 8000 0.48 021 1308 6000 -4692 'G' r Onsite swale south side of 35th Avenue L.P. 9+50, Rt. TIME OF CONCENTRATION (Tc), minutes Overland Flaw Channel Flow 290 Ct= 0.15 Z1 7.3 L1 (A) - 0 Z2 = 8.6 N(A) a 0.4 B a 0 S(A) = 0.01 n = 0.03 Tc (A) = 0.00 s = 0.019 d = 0.304 Seomertt B: Ll (B) - 0 N(B) = 0 S(B) = 0 Tc (B) - 0.0 Tc (ch.) 250 Tc(A+B) = 0.00 Tc total 5.00 Intensity = 3.18 0 (estimated ® d) = 1.42 c1s. Time of Concentration = 5.00 minutes PEAK DISCHARGE. 10 YEAR STORM Q=C'I'A= 1A2 C.F.S. NUMBER and TYPE of DRYWELLS PROPOSED 0 Sirgte-Banal (Spokane County Type A) 1 Double-Barrel (Spokane Cpu dy Type B) OutflowProvded: 1 c1.s. '208' TREATMENT VOLUME Required GPA pond m votume: Impervious '208' Area z 12' - 495 cu. tL volume provided at 6' depth a 713 cu. R OK STORM STORAGE VOLUME Mwdmurn store" required n 271 cu R volume provided at 8' depth 713 cu. ft. OKI SkY wwn Engbow,% Im 909 North Argonne Rba Spokane. WA 9M2 (50) 926-1322 n Stormwater Drainage Report H. STORMWATER DRAINAGE CALCULATIONS: continued Basin G Curb Opening at Low Point, Sta. 9+50, right, 35`b Avenue h = 8 in. = 0.67 ft. Total height of opening H = 0.094 ft. Depth of water at entrance Q = 0.23 cfs Total peak rate of flow Q = 3.087(L)(H)32 for H/h < 1, 0.094/0.67=0.14<1 L = Q (3.087)(I~32 = 0. 23 . (3.087)(0.094)32 = 2.59 ft. 4 Construct Curb Opening; ~'ft. wide, 8 in. deep h Z e ~h . - 0.6, . 4{ Z 0.304 ~t Q = 1.41. c-' s a Curb Inlet n7 `G X + = J 3 z Q t308-I)t1) L = . ~/t : -4Z C3.o8l~~p.3o4~/ z = 2 ,15 G 4 , OKAY ..u d a y:3~,«~iY~'~'r,3'~:~'~F~~'~'~^►~%'t~l• •t~,":r'~Sr~D-.?;5?~`+~`~Y~"i-9~x"~' `.~'.,.~:v- =`"'?'~OJ~~+;~;~lR~+~'~-r.~ie:•~,'~s"s RATIONAL FORMULA HYDROLOGY ° 4. N 1.4 4" 1.4 Date: 9/16198 Design: kwm OiskRUK A11rmamA1M1?838~Qs Basin Name: 'G' Project Name: Midilome East 2nd Addition Project Number: 12838 Site Location: N 12, S. 34, T. 25 N., R. 44 E. W.M. Basin Description: ` Point of Concentration: 35th Avenue Sta. 9+50,18' Right SUBAREAS: Description Acres C A'C Pavement DRAINAGE BASIN ANALYSIS for 10 YEAR STORM EVENT 0.081 0.90 0.073 Total Basin Area, acres = 0.081 Composite Runoff Coefficient = 0.900 Combined (Area ' Runoff Coefficient) = 0.073 TIME OF CONCENTRATION (minutes): Tc (overfand Row) Tc (gutter flow) Ct = 0.15 L2 = 104 Z1 = 36 L1 (A) = 18 Z2 = 0.167 N(A) = 0.016 B= 0 S(A) = 0.0278 n = 0.016 S = 0.0149 Tc (A) = 0.21 d = 0.094 L1 (B) = 0 Tc (gut) 1.19 N(B) = 0 Tc(A+B) : 021 S(8) = 0 Tc total 5.00 Intensity - 3.18 Tc (B) = 0.0 Holding 3.71 0 (esSrrrated ® d) = 0.23 c f.s. Time of Concentration = 5.00 minutes Intensity-Duration for 10•vear Storm Event Time Time Intensity Incnnnt Incrmnt (min.) (sec.) (inJhr) (011M 5.00 300.00 3.18 5 300 3.18 10 600 2.24 15 900 1.77 20 1200 1.45 25 1500 121 30 1800 1.04 35 2100 0.91 40 2400 0.82 45 2700 0.74 50 3000 0.68 55 3300 0.64 60 3600 0.61 65 3900 0.60 70 4200 0.58 75 4500 0.56 80 4800 0.53 85 5100 0.52 90 5400 0.50 95 5700 0.49 100 6000 0.48 PEAK DISCHARGE. 10 YEAR STORM: C = C •I• A = 0.23 C.F.S. SPOKANE COUNTY PUBLIC WORKS DEPARTMENT DIVISION OF BUILDING AND PLANNING CURRENT PLANNING SECTION MEMO June 17, 1996 TO: Pat Harper, County Engineers FROM: Steve Davenport,Planner I RE: Midilome East First Addition,PE-1751-96. Attached is a check from Midilome Inc.for$5,000 for the traffic signal improvement at 32nd and SR-27 per the mitigation agreement for the above final plat(see MDNS agreement and subsequent letter from DOT dated June 17, 1996). Unless you have additional concerns with the final plat, I will proceed to establish it for approval at the June 25 BOCC meeting. This document contains confidential banking information that is redacted pursuant to RCW 42.56.230(5). You may petition for a review of our findings pertaining to any C:Dave Berto redacted or withheld documents pursuant to Spokane Valley • Municipal Code (SVMC) 2.75.080; and obtain judicial review pursuant to RCW 42.56.550. 1435 I MIDILOME INC. 12z 222 N 1250 ` PAY / i' //_ - 19,l -r TO THE 2. OROER OF /�� z_ / `� - - 6. BANK DOLLARS r egPsogF/ENB BRANCH WE$T SpE TFi1F10AVEA1llE / SPOKANE•WO6TI NGTON 99PA: j r UB BANK OF WAHlitNGTDN.NATONA<ASSOC ATfON ^4 L _ _ ��j r TABLE OF CONTENTS J Page SUMMARY INTRODUCTIL]N l CU`R.RENT CONDITIONS . , • . . ,INTERSECTION AND ROADWAY CONFIGURATIONS 7 State Road 27 Z . , , 32nd Avenue 7 TRAFFIC PATTERNS INTERSECTfON OPERATIONS 2 Level of Service Criteria • - • . . . 2 2 Weekday Am Peak: Hour • . Weekday P;vf Peak Hour a 3 BACKGROUND CONDITIONS TRAFFIC VOLUMES 4 INTERSECTION OPERATIONS . Weekday AM P- -,;k Hour 4~ Weekday PM Peak Hour 4 PROJECT IMPACTS DESCRIPTION OF SITE , . . . 5 SITE TRAFFIC 5 Trip Generatiun 5 'T'rip DlstrfbutSori 5 Trip Assignment TOTAL TRAFFIC VOLUMES INTERSECTION OPERA" i(?tS 6 Weekday AM Peak Hour 6 b Weekday PIvt peak T3oiir RECOMMENDED INIPROVE:MENTS7. IMPROVEMENT OPTION 1 7 IMPROVEMENT OPTION , i IMPROVEMENT OPTION 3 8 CONCLUSIONS 3 Improvement Option i 9 14 Intersection Option III Intersection OTon ] . . . Recommendation to _ to f=4 Ir_ a l 6]LS : L'7 4f: At i, - -:'S = + +F rU-~i Q 4 Traffic Impact Report Proposed INfidilome East Development Spukane, Washington August 1994 Prepared for Midilome, Inc. ~lf_rrr; 1"? ?a {Y6:213P 1 DG'S ~+3=`,: , :PrLPHD P. LIST OF TABLES No. Title Page 1. Summary of Intersection Operas=_ons . iv 2. Vehicular 'rip Generation . . . . . . . 5 3. Comparison of Intersection operations with Improvement Option 1 . , . 7 4, Comparison of Intersection Operations with Improvement Option 2 8 5. Comparison of Intersection Operations with Tmprovement Option 3 , . 9 6. Proportion of P.?+f Peak Hour Traffic Contributed by Midilome East Development It LIST OF FIGURES iVo, Title Follows Page 1. Vicinity flap . . 2 ? . 1993 Existing Conditions . . . . . . . . , , 2 3. 1996 Background Conditions , , . . , . 4 4. Project-Generated Traffic Distribution 6 Project-Generated Traffic Volumes , 6 6. 1996 Total Conditions 6 vii L1_i, `J .?-1 Cl6 ~ 4F-N 'T f r ~`I! J- =Ftl JI +P TIL Hr it rr ~ i T.NBLE OF CONTENTS (continued) Page APPENDICES APPENDIX A - Level of Service. Definitions APPENDIX 8 - SR 27 and Sind Avenue 1993 Inters--:tion Counts APPENDIX C - Midilome East Development Project Trip Generation APPENDIX D - Traffic Operations Backup Data Existing Intersection Configuration APPENDIX E - Traffic Operations Backup Data Improvement Option. 1 APPEND X F - Traffic Operations Backup Data Improvement Option ? ~r APPENDIX G - Traffic Operations Backup Data Improvement Option 3 APPkENw'DIX H - Traffic Signal Warrant Testing Improvement Option 3 ct HIJ'6 c'-:' '94 l t6 : ,:t:Pl'l C';, yrr ' 'Ht i CLPI ID F'. S UIN +fARY Our assessment of the intersection of 32nd Avenue and SR 27 indicates the proposed Miclaome East Development would have an aotiecable impact on the intersection operations. Although the future traffic operations could be improved by changing the stop-sign control, particularly with a four-way stop-sign control, stopping traffic on SR 27 is a concern for several reasons. including high travel speeds and roadway functionality. Therefore. a traffic signal is ultimately the best control for this intersection. While a traffic signal will also stop some traffic on SR 27. with proper signing, drivers approaching the intersection on Set 27 could be alerted to the upcoming signal so they will be prepared to stop, if receded. Because the MUTCD traffic signal warrants are not met by the volumes projected for the 1996 ~!:f Jll condition with the Midilome East Development, the cost for addiaig this signal should be shared by both the -existing users and other future development. The proportionate cost of a S 150,000 traffic signal would be about S10,000 (6 to 7 percent) for Midilome East. The analysis for the 1993 existing, 1996 background. 1996 total, and 1996 mitigated conditions is shown in the table below. TABLE 1 Summary of intersection Operations Current atop,Sign Control Trn lic Signal as on 32nd Avenue 'Xitigation Measure 1993 1996 1996 t996 1996 Intersmlion Existing Background Totxi Background Total Weekday AM Pear Hour Eastbound LTR C D ❑ $ S Westbound L I R C D E B 8 NorThbound L A A A C C TR A A A B R Southbound L A A A C C TR A A A 13 B Weekday AV Peak flour - - - Easftuad LTR B F F 8 B Wastbound LTR E ,F F B S Northbound L A A A C L TR A A 9 B Southbound L A A A ❑ D TIZ A A A 8 B (V 1-° IJI-a ."3 ?_S L: : ~I IF't! C~I°~`~' ~ iHh!•a _ ..'I_ F=t' r~ ^[V'~~! .may INTRODUCTION The purpose of this report is to identify any improvements that may be necessary at the intersection of SR 27 and 32nd avenue due to the proposed Midilome East Development. This analysis was requested by the Washington State Department of Transportation (WSDOT) to determine if the proposed Midilome East Development would trigger the need for a traffic signal. For the analysis, the proposed Midilu me East Development, consisting of 127 single family residential units, was assumed to be fully occupied by the fall of 1996. An existing condition, based on 1993 traffic counts at the intersection, was examined. Background traffic volumes were projected for 1996 based on wi annual growth gate and combined with projections for the proposed 'rl€dilome East Development, Weekday AIM and FM peak hour traffic was analyzed for all three of these conditions. This report contains discussions and summaries of all of the analyses performed and appendices contain the full analysis output. F }y 4 _ Y ~2 CURRE T CONDITIONS Before determining the future intersection requirements, DEA analyzed the existing intersection operations, INTERSECTION AND ROADWAY CONFIGURATIONS The intersection of SR 27 and 32nd Avenue is located on a state highway facility in the Spokane County, Washington. It lies in an area which is primarily residential, with most of the commercial development to the north, A vicinity reap showing the intersection with respect to the proposed Midilome East site and the surrounding street system is shown in Figure t \IT-L'.U State Read 27 State Road 27 is a state facility running north and south through the City and County of Spokane. It connects with some of the major commercial corridors, and it has all interchange with Interstate 90. At the intersection with 32nd Avenue, SR 27 is a three-lane roadway: one moving lane in each direction with a center turn lane. The speed limit is 50 miles per hour. 32nd Avenue Thirty-second Avenue is one of the only continuous east/west roadways running through a primarily residential area. It is rwo lames wide, with one travel lane in each direction. At the intersection with SR 27, 32nd Avenue is controlled by stop signs. The speed limit is 35 miles per hour. TRAFF'IC PATTERNS Current traffic volumes were measured in July of 1993. The weekday AAFI and P%4 peak hour volumes arc shown in Figure The weekday PM peak hour is the period of highest activity During both the AM and M peak hours, the traffic volumes on 32nd Avenue are equai to or higher than those on SR 27. I`-MRSECTION OPERATIONS The Level of Service {LOS) of each 'ane at the intersection was calculated :or each of the peek hour conditions. The LOS for each time period is shown in Figure Level of Service Criteria The Level of Service criteria at an unsignaiixed intersection in an urban area is defined in Appendix Table A-1. This table defines the Level of Service concept With LOS A representing 2 F^ LID Legend] RO 44 Traffic Volume Not to Scale A Level of Servrce DAM ctiA%--' AnD A.)MCfAM, I.11C. x r-- :4 ■ t75 14 A ~I 4- ! Fl~ Avenue 41 fd6 ~F 2fl • ~a rt+ r, ~ r A. Weekday ASK Peak Hour Traffic 4! 14 f Q ~ Y2 ad Avenue I d -Z C. W-:--day ,-L'rl Peak Hour Gp.:ra[locs aG r• r A ~ ~ I 21 I ' 33nsf Avenue 3fl ' i 153 B. Weekday FM Peak 1$our Traffic = t. r A V 3 rnd i .-Avenue i D. Wdek&v P.f Peak Hour Operactous FIGURE 2 t993 EXISTING CONDITIONS