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HomeMy WebLinkAbout18 - Design Report - Safeway Fuel Station #2999 - Stormwater STORMWATER SITE PLAN Safeway Fuel Station #2999 Northeast Corner of North 19th Avenue and West Main Street Bozeman, Montana Prepared for: Safeway Inc. 1121 - 124th Avenue N.E. Bellevue, WA 98005 F, 0jm""' I Revised July 11 , 2018 Revised April 11 , 2018 ,- 3 261G November 18, 2013 i MENT OF Our Job No. 16425 OPMENI. �01,1 T Atv fit HAL P. GRUBB i `59 �0 ONA` ¢�'►l�S Z 18215 72ND AVENUE SOUTH KENT,WA 98032 (425)251-6222 (425)251-8782 FAX BRANCH OFFICES • TUMWATER,WA o KLAMATH FALLS,OR ♦ LONG BEACH,CA a ROSEVILLE,CA ♦ SAN DIEGO,CA o U www.barghausenxom 2 ? <r j NG ENGINE ` TABLE OF CONTENTS 1.0 PROJECT OVERVIEW 1.1 Purpose and Scope 12 Pn+Deva|opedCond|Uona 1.3 PootOava|opedCondiUona 2.0 PRELIMINARY CONDITIONS SUMMARY 2.1 General Requirements 2.2 Drainage Basin 2.3 Soil Conditions 3.0 C)FF'G|TEANALY8|S 3.1 Upstream Tributary Area 3.2 Downstream Analysis 4.0 RETENTION/DETENTION ANALYSIS AND DESIGN 4.1 Existing Site Hydrology 4.2 Developed Site Hydrology 4.3 Hydrologic Analysis 4.4 Rehenbon/OebanUon8ystem 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 5.1 On-Site Conveyance System 6.0 SPECIAL REPORTS AND STUDIES 7.0 OPERATIONS AND MAINTENANCE MANUAL 9.0 CONCLUSION TABLE OF EXHIBITS EXHIBIT A-VICINITY MAP EXHIBIT B-SCS SOILS MAP EXHIBIT C-PRE-DEVELOPED BASIN MAP EXHIBIT D-DEVELOPED CONDITIONS BASIN MAP EXHIBIT E-RETENTION/DETENTION ANALYSIS AND DESIGN EXHIBIT F-CONVEYANCE ANALYSIS EXHIBIT G-OPERATIONS AND MAINTENANCE MANUAL EXHIBIT H -FEMA MAP EXHIBIT I-DOWNSTREAM DRAINAGE PATH MAP 16425.001.doc Tab 1 . 0 1.0 PROJECT OVERVIEW 1.1 Purpose and Scope The proposed Safeway Fuel Center#2999 project consists of approximately 0.8 acres of land located at the northeast corner of N 19th Avenue and W Main Street in the City of Bozeman. The existing site is currently used as a casino with associated landscaping, parking and utilities. Please see the vicinity map included as Exhibit A. This report provides site information and an analysis used to design the stormwater facilities that will provide the detention, water quality, and conveyance for approximately 0.8 acres pursuant to development. This report is based on the requirements of the March 2004 Design Standards and Specifications Policy for the City of Bozeman. 1.2 Pre-Developed Conditions The proposed project site consists of 0.8 acres of land located at the southwest corner of the existing Safeway store development. The existing site includes a casino building with associated driveways, parking, landscape and utilities. The project site is bounded by N 19th Avenue to the west, W Main Street to the south, an existing access drive to the north and the Safeway development and parking lot to the east. The pre-developed site is highest in the middle at the building, with runoff directed toward the surrounding curb line. It appears runoff is directed to the northwest corner of the site where there is an area of rock and a storm water manhole or vault. The structure was full of sediment so it is difficult to determine but it is assumed that the site discharges to the existing conveyance system within N 19th Avenue. Further field investigation has determined there is no working discharge from this site. The structure and pipes are plugged with sediment and an outflow path cannot be determined. It is assumed most runoff infiltrates on site with the existing structure used for emergency overflow only. 1.3 Post Developed Conditions The proposal for this project is to construct a gas station with a fuel island canopy, kiosk and an additional retail space. The project would also include a pedestrian plaza at the southwest corner adjacent to the N 19th Avenue and W Main Street intersection. Approximately 0.8 acres of the developed site will be collected and conveyed to one of the proposed infiltration basins. A rain garden is proposed south of the proposed building that would collect surface runoff from the adjacent landscaping and runoff from the building roof. Water would be allowed to infiltrate through the soil and/or pond approximately 6 - 12 inches. The fueling area under the canopy is graded to drain to a catch basin in the northwest corner of the canopy. The under canopy drainage will be conveyed through an oil/water separator before entering another proposed basin at the northwest corner of the site. Site runoff will be directed to this same basin at the northwest corner of the site for infiltration. The infiltration system has been sized to infiltrate the 10-year, 2-hour storm intensity event in the post-developed condition required by the City of Bozeman design manual. 16425.001.doc Tab 2.0 PRELIMINARY CONDITIONS SUMMARY 2.1 General Requirements The proposed development requires a lot line adjustment. 2.2 Drainage Basin A review of the topographic map and city record information assumes that runoff from the site flows west into the existing underground conveyance system in N 19th Avenue. This conveyance system flows north, eventually discharging to the East Gallatin River. After further site investigation, it cannot be determined that runoff from this site is directed to N 19th Avenue. It is assumed runoff infiltrates on site and only emergency overflows are directed to N 19th Avenue. 2.3 Soil Conditions The USDA soil mapping for the City of Bozeman classifies the onsite soils as Urban Soils, which usually means the study area was already developed when the soil study was conducted. Per the Geotechnical Engineering Report by Terracon for the adjacent Safeway Store development, the existing soil conditions consist of a layer of fill over a shallow clay layer over a medium dense to dense gravel. The groundwater depth in the vicinity of this project is approximately 18.7 feet deep. Please see Exhibit B SCS soils map. 16425.001.doc Tab 3.0 OFF-SITE ANALYSIS 3.1 Upstream Tributary Area There is no upstream basin contributing runoff to this site except for the adjacent right-of- way from the back of the sidewalk. The existing Safeway store development handles its own runoff as well as some of the existing landscape runoff from this site. 3.2 Downstream Analysis This site discharges during peak storm events, at the northwest corner into the existing storm drainage conveyance system in N 19th Avenue. Runoff is conveyed north in N 191h Avenue in a 66" diameter pipe north to Oak Street. Runoff is directed east in Oak and discharged north into a small stream/drainage channel. This drainage channel continues north, combining with another stream and eventually discharges into the East Gallatin River. Please refer to the attached Downstream Drainage Path Map, Exhibit I. Because no reliable outlet from this site could be found, it is assumed most runoff infiltrates on site. 16425.001.doc Tab 4 . 0 4.0 RETENTION/DETENTION ANALYSIS AND DESIGN 4.1 Existing Site Hydrology The project site is an existing casino with associated parking, landscape and utilities. For the most part the site slopes from the center of the site to the north, east and west. The runoff is directed to the northwest corner of the site to a rock area with a storm water manhole or vault. It is assumed most runoff infiltrates on site and the existing structure is for emergency overflow conditions. 4.2 Developed Site Hydrology Under developed conditions, the existing building will be demolished, and the entire site will be graded relatively flat to tie-in the existing Safeway store site. The proposed project consists of a fuel station canopy over the fueling islands, a kiosk and a retail space. Also included in this re-development project is a pedestrian oriented space at the northeast corner of the N 191h Avenue and W Main Street intersection. Runoff will be routed to one of the infiltration basins for treatment and flow control. The storm drainage proposal conforms to the requirements of the 2004 City of Bozeman Design Standards and Specifications Policy requirements. 4.3 Hydrologic Analysis The infiltration pond sizing was computed using the methodology from the 2004 Design Standards and Specifications Policy. The infiltration pond must be sized for the runoff rate from the 10-year/2-hour storm event. The infiltration basins are sized to accommodate the runoff directed to them. 4.4 Retention/Detention System This project proposes to use an infiltration basin on the south side of the project to collect runoff from the building roof and surrounding landscaping. Runoff will infiltrate through the soil and will pond 6 - 12 inches. The roof from the canopy and the parking lot surface flow will be directed to the northwest corner. The under canopy drainage will be sent through an oil/water separator for additional water quality treatment prior to being discharged to the infiltration pond. A gate valve is also proposed downstream of the oil/water separator so that it can be closed in case of an accidental fuel spill. The calculations to show that detention is not required, as well as sizing the infiltration basins can be seen in Exhibit E Retention/Detention Analysis and Design. 16425.001.doc Tab 5 . 0 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 5.1 On-Site Conveyance System The conveyance system capacity was designed using the rational method and the 25-yr design storm. See Exhibit F, Conveyance Analysis. All of the pipes are free-flowing with no surcharge. 16425.001.doc Tab 6 . 0 6.0 SPECIAL REPORTS AND STUDIES The following report has been prepared for this project site to date: • Traffic Analysis by Morrison Maierle, Inc. dated November 7, 2013 16425.001.doc Tab 7 . 0 7.0 OPERATIONS AND MAINTENANCE MANUAL See Exhibit G. 16425.001.doc Tab 8 . 0 8.0 CONCLUSION This proposal meets all the requirements of the City of Bozeman as mentioned in the 2004 Design Standards and Specifications Policy. Therefore, this project should be accepted as proposed. 16425.001.doc Exhibit A Vicinity Map City of Bozeman GIS Page I of I x4r, -w Wfflll lvr 105 .4 .if qjT �' I I : � 1! all rT' r� a .� � I� a� r,F( r 'Ayi Ij 17 TAl aff-1, M ro A T0. IL r_ it4 C`b a' �-�JN'l ,fiFti tie J Street Names Roads Aerial Photo (5/12/12) ORed: Band—I ALLEY ALLEY OGreen: Band-2 DRIVEWAY DRIVEWAY []Blue: Band-3 UNK UNK Vi cl 111� q litti-)-//Pis.hozeiiiaii.iiet/ast)net clieiit/ESRI/WebADF/Pi-iiitTaskLayoutTeiiiplates/deftult.li... 11/18/2013 Exhibit B SCS Soils Map z z Q ` P O P C OTSBSOS 0058505 06bBSOS OBb8505 OLb8505 0968505 05b8505 0bb8505 0£b8505 co Cl) M,b£,E oITT _.. I $ I _ M„6£.E oITT `O O z Ag 43.. 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CL 3 N o `O 0- �. 3 v) 0 a) 2 0 0 W o O o_ a o_ a oa ❑ a T o `o C3 m ° � cn m m a co ca ca y 7 U) a — LL `p C N Q m 2 2 � LL 3 o T h > > `0 m m c°i m Y d Y 0 'O 'Q 'Q C O `0 N O N n) C D o o m N N c = 0 co co cn a m m U U (7 (D J J 2 .2 2 a w cn v> m in U) cn a a a) C V 10 ' N V CD OM Q 0 N O O 0 uj O � m � a1 N mN0 O ZU O �Ir Soil Map—Gallatin County Area,Montana Map Unit Legend Gallatin County Area,Montana(MT622) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI UL Urban land 1.3 100.0% ------V.._ — --- — — --------- -- - Totals for Area of Interest 1.3 100.0% ------ - - USDA Natural Resources Web Soil Survey 11/14/2013 Conservation Service National Cooperative Soil Survey Page 3 of 3 Exhibit C Pre-Developed Basin Map EXISTING CONDITIONS MAP 1..20- 0 10 20 40 0.436 ACRES I I I I I I I 1 -0 LOT 1B 5.695 ACRES ,: I , / / I , REVISION SCHEDULE [DELTA]NUMBER I SCHEDULE I IORC tin SWAnAL ......... BASED SS CRITERIA#USTER ISSUED;OW25111 -7- I l 1 I 0 ------------ W� ----------- I I t2 N In In N '`I N i I `�3 i I -I; I'S % '�� � b8 I CO NBJ • PROJECTNO. z------ 16425 co D"A"'Y' RDC CHECKED BY: KEH hy c: cy) 0-) lip co .71 LLJ 0 06 c: co a) q E > 0------------- < im la < U) -- -- - - - - -- - - - -- - - -- SHEET TITLE EXISTING CONDITIONS MAP SHEET NO. 1 OF 1 Exhibit D Developed Conditions Basin Map b DEVELOPED CONDITIONS MAP 0 10 20 40 I it i, LV 1 1L1. I A i 1• o I I } i 1 ;i , ) •, [ I # �' ;� rr_- ;I � —t- _ — _ ---- ----- — ---- ���OT ll - L REVISION SCHEDULE DELTA NUMBER DATE r• , Ioil a 7 1 Imo_ i r I ; r 1 0 I � ifI I - i BASED CRITERIA11nSTER i ISSUED �S I 1 i — h i���" r '� �� " �; �� r11ji ','.. �,..-.✓.'""'"� Q .�j2201F O 1% I , n -' - \n " �� 1 !' � I : r =— 1 ' � 'I 1 1 I N4 1��•'"�� I, ;f.f -- _ �Y�� c�In 17r — • --1Q— ! T�pf! x I i 1 I I ON,. i fit ` r s F y ti . : ,�` ? _—r a8 c caa� , '> i `j,{ �- ._1... I ���` � PROJECT NO 1M1 I rr I , w _x 16425 i 4*h „ p /" - ! 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MAIN STiw SHEET TITLE I ,a — - - DEVELOPED CONDMONS MAP SHEET NO. 1 OF 1 Exhibit E Retention/Detention Analysis and Design Site Summary Retention Volume (10-year, 2-hour storm) Q = CIA V= 7,200 Q (cf) C = weighted C factor I =0.41 in/hr A= area (acres) Q = runoff(cfs) V=volume (cf) Infiltration Basin#1 Basin Area C Q = GI A CB#1 0.06 0.35 = (0.60) (0.41)(0.36) CB#2 0.12 0.60 Q = 0.08856 cfs B#3 0.03 0.90 CB#6 0.08 0.40 V= 7,200 Q Roof 0.07 0.90 V= 638 cf required Total 0.36 ac V= 797 cf provided Weighted C =0.60 Infiltration Basin#2 Basin Area C Q =CI-A CB#4 0.16 0.90 = (0.78) (0.41)(0.40) CB#5 0.06 0.90 Q=0.1279 cfs Canopy 0.10 0.90 NW 0.08 0.30 V= 7,200 Q V= 921 cf required Total 0.40 ac V= 946.5 cf provided Weighted C = 0.78 16425.001.doc — O I I I IW I I I I ti LO ��� x x X k X I I I CO U— `o rrlo rn o i II z o 0 0 6 6 - W}� II II II �I II II II I 1 CL �U :3 o CD o In O o I u) U <W z w I I II N O `O I v U) Q < I OLli z I I -- --i Lco o z I I oQ ZW LU N Z m I LO z O I O I r O I I IQ i I I I I I � t � co LO ^V' co N r O �=H 2Ed S3HONI NI AIISN31NI WJNIVd FIGURE I-2 RAINFALL INTENSITY—DURATION IN MINUTES 31 Exhibit F Conveyance Analysis CONVEYANCE MAP 1*-20' 0 to 20 40 AL 1 r-k J; JID V(� LOT IB "T, REVISION SCHEDULE IDELTA I NUM5ER 11 DATE TV • [p N 4_ --- --------I BASED ON C ITERIAFMSTER B #2 1 ----------- ISSUED OW75�1 I A�SJN AW NW BASIN -------- ------------ 'AREA-0.08 AC C-43 CS#4 AREAC -Q16 A n, C-0.9 CANOPY - --------- C-09 10 AC AREA-0 J, is Y 1 QBW �J J, /AREA-0. AC - PROJECT NO 16425 C0.4 ROOF z OB#5 4 AREA-0.07 AREA-0.06 AC DRAWN By RDC C-09 C-019 ------0-- A CHECKED BY f. CS 0 K E H ----------- -0.03 AREA AC C-DAI F771 CD --------- - lz, --- ---- - ry ca t cu c OB LLJ -0,06 AC AFEA ----4 06 AREA-0.12 AC C-0.35 77 c: <U- >_ = 0 ----------__ - < co WLMATM wa BASIN#1 ------- ui Ll_ SHEET TITLE CONVEYANCE MAP SHEET NO. 1 OF 1 11 II O O O O O O O O II cN. Oct O ip 11 It N O O O N 11 11 p tq N INN m O O I[Oi 11 a 11 � A A 0p m N N N II N M V N 10 t•AJ 0 II 110 O O O O O O O Z d 11 Ot O M n M N N O 'O II O M O O 7 N N M U O Z Q Z _ 11 N D7 N N m O O N Z W11 0 O lV(V O O O N C w 0 N cd r M II O 06 Cl! m N N C Q W W 0 11 C i O .0 O c o o J 10 U Q 11 II J tD N C tp A II LL N J Q C 10 Z O O(O o N 11 m m M m M M M m Q O O CSCi II GO G6 W CJ N N tD m O p 11 M C7 M m m m fM 110 0 Q m 1- 0 m N cr LL N !-O•- w m�OAmO W x 11 O O 99 q q O N Z) 0 00 0 000 a �i ¢ p¢ F- ` n u N N II 11 LL II WON Z O W o U 11 O 00 .0 O cc W LL Q Z 1-j-O N O O Q 11 O O 66 O 666 11 It Q II w �C0 � W M II O O O- 7 O O N (�cG H N p N I I O O 00 O 000 ZOO Z LL m05 Fa O 11 °' o cio 0 000 Z 2 Ow n o O Z O Iu c ❑ ^ y u Z o w m E Er N g a ^ II o 0 0 0 0 0 0 0 Qmo x 5 m C9 of`o 3 mo v.o 11 0 0 ov o oN lh m U LL N LL e L ~ II o N 0,6 N O b O 3 T O O a o a 11 m O �2�2 o W O 4! O O N C > o m a c m u ICI LL>yO7 cG~ J II O O ih< fAD NO(O OO P> N IC F 11 II 11 N 11 O O tO N O ul t0 N II O N 00 N 000 m u m n d Ilo 0 00 0 000 c u 0 d o m vo c F h m Ix- wo� E p O 0 a 0 �t N a#co in Z ?? Z It U 0 U U p <0 '-c-- d 11 O O O O a it MECO ova n.J O W U U m o Q m u LL Y w M W w c� w y'yrE o o a O 11 u p a * p v-<a Q w c c E c E m Kum O m m Z m m z 0 �F 2 � mm LL11U x UU Q U U m U =0 J u U Exhibit G Operations and Maintenance Manual OPERATIONS AND MAINTENANCE MANUAL Safeway Fuel Station #2999 Northeast Corner of North 19th Avenue and West Main Street Bozeman, Montana Prepared for: Safeway Inc. 1121 - 124th Avenue N.E. Bellevue, WA 98005 Revised July 11 , 2018 November 18, 2013 Our Job No. 16425 CyHAV m Z 18215 72ND AVENUE SOUTH KENT,WA 98032 (425)251-6222 (425)251-8782 FAX BRANCH OFFICES ♦ TUMWATER,WA • KLAMATH FALLS,OR ♦ LONG BEACH,CA • ROSEVILLE,CA • SAN DIEGO,CA °y ? www.barghausen.com y' 16425.002.doc r'NG ENG1N�� Site Address: The project is located at the northeast corner of N 191h Avenue and W Main Street in Bozeman Montana. Introduction: The proposed Safeway Fuel Center#2999 consists of approximately 0.8 acres of land adjacent to the existing Safeway development. The site is currently a casino with driving surfaces, parking areas and landscaping. This site is being redeveloped with a fuel station and retail space with associated parking and utilities. The proposed project site was designed to meet the City of Bozeman requirements. The following pages of this report delineate maintenance requirements for each feature of the storm drainage facilities constructed on site. Each feature delineated in the appendix of this report should be monitored twice per year at a minimum, and more often if maintenance requirements appear to indicate further review of each system is required. Plan Goal: The specific purpose for the stormwater facility is to minimize pollution that is typically associated with modern development. In general, pollution from motor vehicles and pollution generated from erosion. Attached to this narrative is a maintenance manual, which offers guidelines to the owner for stormwater facility maintenance. Prevention BMPs: The catch basins and conveyance pipes within the right-of-way should be inspected and maintained by the city. The two infiltration basins will be visually inspected for accumulation of debris and silt and will be maintained as required by this maintenance plan and attachments. • Maintenance Standards for Drainage Facilities No. 1 — Ponds No. 2—Infiltration Facilities No. 5 —Catch Basins No. 7 —Energy Dissipaters No. 10—Conveyance Systems No. 11 —Grounds No. 22—Baffle Oil/Water Separator These standard maintenance requirements were taken from the King County Surface Water Design Manual, 2005. These shall be replaced with City of Bozeman or State of Montana standards if they are more stringent. Treatment BMPs: A pond has been designed to provide a settling area for sediment. The pond was designed to provide treatment area based on the design flow rate. The detention pond will detain water and release at maximum release rates allowed. The City of Bozeman is to review and approve any changes to this stormwater Maintenance Plan prior to changes in its implementation. Additionally, any changes in ownership or person of responsibility are to be reported to the City of Bozeman. 16425.002.doc Inspection/Maintenance: Regular inspections of the drainage facilities should be carried out twice per year, in the spring and fall. One inspection should be during the month of September to identify and correct any problems prior to the winter season. The responsible party should keep records of these inspections available for review by the City. Additional inspections may be required after severe seasonal storms. Routine maintenance of the site will include mowing, care of landscaping and the removal of trash and debris from the drainage system. The streets and driveways should be kept clean and in good repair. Events such as major storms (more than 1 inch of rain in a 24 hour period) or heavy winds will require immediate inspections for damages. To ensure proper water quality and treatment, the pond must be properly maintained. Be careful to avoid introducing landscape fertilizer to receiving waters or groundwater. If pond side slopes become eroded over 2 inches deep, stabilize by using appropriate erosion control measures (e.g., rock reinforcement, planting of grass, compaction). Use photocopies of these pages to check out the problems you should look for during an inspection. Copies of the included construction plan sheets would be useful during field inspections to identify areas that need maintenance and to make sure all facilities are inspected. Add comments in the Inspection Results field and note the actions taken. Keep these check sheets in your files. The maintenance records must be kept on file to be reviewed by the City of Bozeman personnel at their discretion. Person of Responsibility: TBD Design Engineer: Barghausen Consulting Engineers, Inc. 18215-72nd Avenue South Kent, WA 98032 (425)251-6222 Plan and/or Information Updates: The City of Bozeman is to review and approve any changes to this stormwater Maintenance Plan prior to changes in its implementation. Additionally, any changes in ownership or person of responsibility are to be reported to the City. 16425.002.doc INSPECTION/MAINTENANCE CHECKLIST STRUCTURE DATE OF INSPECTION/MAINTENANCE Results/ Maintenance Date COMMENTS Infiltration Basin#2 at Inspection the NW Corner Results Maintenance Done Infiltration Basin#1 Inspection South of the Building Results Maintenance Done Catch Basins/Pipe Inspection System Results Maintenance Done Grounds Inspection Results Maintenance Done Oil/Water Separator Inspection Results Maintenance Done 16425.002.doc Maintenance Standards for Drainage Facilities The facility-specific maintenance standards contained in this section are intended to be conditions for determining if maintenance actions are required as identified through inspection. They are not intended to be measures of the facility's required condition at all times between inspections. In other words, exceeding these conditions at any time between inspections and/or maintenance does not automatically constitute a violation of these standards. However, based upon inspection observations, the inspection and maintenance schedules shall be adjusted to minimize the length of time that a facility is in a condition that requires a maintenance action. KING COUNTY, WASHINGTON, SUR E WATER DESIGN MANUAL, E Jr off Air r EN"Mal MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 1 -DETENTION FONDS Maintenance Defect or Problem Conditions When Maintenance Is Needed Results Expected When Component Maintenance Is Performed General Trash&Debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Poisonous Vegetation Any poisonous or nuisance vegetation which may No danger of poisonous vegetation or Noxious Weeds constitute a hazard to County personnel or the where County personnel or the public. public might normally be. Coordination with Seattle-King County Health Department Contaminants and Oil,gasoline,or other contaminants of one gallon No contaminants present other than Pollution or more,or any amount found that could: a surface film. (Coordination with 1)cause damage to plant,animal,or marine life; Seattle/King County Health 2)constitute a fire hazard;or 3)be flushed Department) downstream during rain storms. Unmowed if facility is located in private residential area, When mowing is needed, Grass/Ground Cover mowing is needed when grass exceeds 18 grass/ground cover should be inches in height, In other areas,the general mowed to 2 inches in height. policy is to make the pond site match adjacent Mowing of selected higher use areas ground cover and terrain as long as there is no rather than the entire slope may be Interference with the function of the facility. acceptable for some situations. Rodent Holes Any evidence of rodent holes if facility is acting Rodents destroyed and dam or berm as a dam or berm,or any evidence of water repaired. (Coordination with piping through dam or berm via rodent holes or Seattle/King County Health other causes. Department) Insects When insects such as wasps and hornets Insects destroyed or removed from interfere with maintenance activities. Mosquito site. Mosquito control: Swallow complaints accompanied by presence of high nesting boxes or approved larvicide mosquito larvae concentrations(aquatic phase). applied. Tree Growth Tree growth threatens integrity of berms acting Trees do not hinder maintenance as dams,does not allow maintenance access,or activities. Harvested trees should interferes with maintenance activity(i.e.,slope be recycled into mulch or other mowing,silt removal,vactoring,or equipment beneficial uses(e.g.,alders for movements). If trees are a threat to berm firewood). integrity or not interfering with access,leave trees alone. 2005 Surface Water Design Manual—Appendix A A-1 1/24/2005 APPENDIX A MAINTENANCE REQL,,AEMENTS FLOW CONTROL,CONVEYANCE,A. WQ FACILITIES NO. I - DETENTION PONDS Mainterance Defect or Problem Conditions When Maintenance Is{Needed Results Expected When Component Maintenance Is Performed Side Slopes of Pond Erosion Eroded damage over 2 inches deep where cause Slopes should he stabilized by using of damage is still present or where there is appropriate erosion control potential for continued erosion. measure(s);e.g.,rock reinforcement,planting of grass, Any erosion observed on a compacted berm compaction. embankment. If erosion is occurring on compacted berms a licensed civil engineer should be consulted to resolve source of erosion. Storage Area Sediment Accumulated sediment that exceeds 10%of the Sediment cleaned out to designed designed pond depth. pond shape and depth;pond reseeded if necessary to control erosion. Liner Damage Liner is visible and has more than three V.-inch Liner repaired or replaced. (if Applicable) holes in it, Pond Berms(Dikes) Settlement Any part of berm that has settled 4 inches lower Dike should be built back to the than the design elevation. Settling can be an design elevation. indication of more severe problems with the berm or outlet works. A licensed civil engineer should be consulted to determine the source of the settlement. Emergency Tree Growth Tree growth on emergency spillways create Trees should be removed. If root Overflow/Spillway blockage problems and may cause failure of the system is small(base less than 4 and Berms over 4 berm due to uncontrolled overtopping. inches)the root system may be left feet in height. in place. Otherwise the roots should Tree growth on berms over 4 feet in height may be removed and the berm restored. lead to piping through the berm which could lead A licensed civil engineer should be to failure of the berm. consulted for proper berm/spillway restoration. Emergency Rods Missing Only one layer of rock exists above native soil in Replace rocks to design standards. Overflow/Spillway area five square feet or larger,or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. 1/24/2005 2005 Surface Water Design Manual—Appendix A A-2 APPENDIX A MAINTF .-,,NCE REQUIREMENTS FOR FLOW CONTROL NVEYANCE,AND WQ FACILITIES NO. 2-INFILTRATION FACILITIES Maintenance Defect or Problern Conditions When Maintenance Is Needed Results Expected e Maintp Performed Component Infiltration Pond Trash&Debris See"Detention Ponds"Table No.1 See"Detention Ponds"Table No.I General See"Detention Ponds"Table No. Poisonous Vegetation See"Detention Ponds"Table No.1 or Noxious Weeds Contaminants and See"Detention Ponds"Table No. 1 See"Detention Ponds"Table No. 1 Pollution Unmowed See"Detention Ponds"Table No.1 See"Detention Ponds"Table No.1 Grass/Ground Cover Rodent Holes See"Detention Ponds"Table No.1 See"Detention Ponds"Table No. i Insects See"Detention Ponds"Table No.1 See"Detention Ponds"Table No.1 Infiltration Pond Erosion See"Detention Ponds"Table No.1 See"Detention Ponds"Table No.1 Side Slopes Infiltration Pond Tree Growth See"Detention Ponds"Table No.1 See"Detention Ponds"Table No. 1 Emergency Overflow Spillway and Berms over 4 feet in height. Infiltration Pond Rock Missing See"Detention Ponds"Table No.1 See"Detention Ponds"Table No.1 Emergency Overflow Spillway Infiltration Facility Sediment A percolation test pit(ponds)or test of facility Sediment is removed and/or facility Storage Area indicates facility is only working at 90%of its is cleaned so that infiltration system designed capabilities. if two inches or more works according to design. Ponds sediment is present,remove. are reseeded if necessary to control erosion. Infiltration Facility Sediment and Debris By visual inspection,little or no water flows Replaced gravel in rock filter. Rock Filters through filter during heavy rain storms. (if Applicable) Infiltration Facility Sump Filled with Any sediment and debris filling vault to 10%of Clean out sump to design depth. Sump Sediment and Debris depth from sump bottom to bottom of outlet pipe (if Applicable) or obstructing flow into the connector pipe. Infiltration Facility Filled with Sediment Sediment and debris fill bag more than 1/2 full. Replaced filter bag or redesign Filter Bags and Debris (if Applicable) Infiltration Facility Sediment Remove when B"or more. Sediment cleaned out to designed Pre settling Ponds pond shape and depth or sediment is removed from vault. Ponds are and Vaults reseeded if necessary to control erosion. Note: Sediment accumulation of more than 0.25 inches per year may indicate excessive erosion is occurring upstream of the facility or that conveyance systems are not being properly maintained. The contributing drainage area should be checked for erosion problems or inadequate maintenance of conveyance systems if excessive sedimentation is noted in an infiltration facility. Check twice a year during first 2 years of operation,once a year thereafter. Clean manholes/catch basins,repair damaged inlets/outlets, clean trash racks. 2005 Surface Water Design Manual—Appendix A A-3 I/24/2005 APPENDIX A MAINTENANCE REQ EMENTS FLOW CONTROL,CONVEYANCE,f WQ FACILITIES NO. 5-CATCH BASINS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash&Debris Trash or debris of more than Y.cubic foot which No Trash or debris located (Includes Sediment) is located immediately in front of the catch basin immediately in front of catch basin opening or is blocking capacity of the basin by opening. more than 10%. Trash or debris(in the basin)that exceeds 1/3 the No trash or debris in the catch depth from the bottom of basin to invert the basin. lowest pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of trash or more than of its height. debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases(e.g.,methane). Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Structure Damage to Corner of frame extends more than Y44 inch past Frame is even with curb. Frame and/or Top curb face into the street(If applicable). Slab Top slab has holes larger than 2 square inches Top stab is free of hales and cracks. or cracks wider than%inch(intent is to make sure all material is running into basin). Frame not sitting flush on top slab,i.e., Frame is sitting flush on top slab. separation of more than%inch of the frame from the top slab. Cracks in Basin Cracks wider than''/x inch and longer than 3 feet, Basin replaced or repaired to design Walls/Bottom any evidence of soil particles entering catch standards. basin through cracks,or maintenance person judges that structure is unsound. Cracks wider than%:inch and longer than 1 foot No cracks more than inch wide at at the joint of any inlet/outlet pipe or any the joint of inlet/outlet pipe. evidence of soil particles entering catch basin through cracks. Settlement/ Basin has settled more than 1 inch or has rotated Basin replaced or repaired to design Misalignment more than 2 inches out of alignment, standards. Fire Hazard Presence of chemicals such as natural gas,oil No flammable chemicals present. and gasoline. Vegetation Vegetation growing across and blocking more No vegetation blocking opening to than 10%of the basin opening. basin. Vegetation growing in inletioutlet pipe joints that No vegetation or root growth is more than 6 inches tall and less than 6 inches present. apart. Pollution Nonflammable chemicals of more than'/:cubic No pollution present other than foot per three feet of basin length. surface film. Catch Basin Cover Cover Not in Place Cover is missing or only partially in place.Any Catch basin cover is closed open catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by on Mechanism opens with proper tools. Not Working maintenance person with proper tools.Bolts into frame have less than%:inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one Remove applying 80 tbs.of lift;intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, Ladder meets design standards and misalignment,rust,cracks,or sharp edges. allows maintenance person safe access. 1/24/2005 2005 Surface Water Design Manual—Appendix A A-6 APPENDIX A MAINT NCE REQUIREMENTS FOR FLOW CONTROL -NVEYANCE,AND WQ FACILITIES NO. 5--CATCH BASINS Maintenance Defect or Problem Conditions When Maintenance Is Needed Results Expected When Component maintenance is performed Metal Grates Unsafe Grate Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable) Opening standards. Trash and Debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. Damaged or Missing. Grate missing or broken member(s)of the grate. =inplacemeets design NO. 6-DEBRIS BARRIERS(E.G.,TRASH RACKS) Maintenance Defect or Problem Condition When Maintenance Is Needed Results Expected When Component Maintenance is Performed. General Trash and Debris Trash or debris that is plugging more than 20% Barrier clear to receive capacity of the openings in the barrier. flow. Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more Bars. than%inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50% Repair or replace barrier to design deterioration to any part of barrier. standards. NO. 7-ENERGY DISSIPATERS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed. External Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rocks to design standards. Rock area five square feet or larger,or any exposure of native soil Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20%of the Pipe cleaned/flushed so that it Sediment design depth. matches design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or Water Property concentrated points along trench(normal rebuilt to standards. condition is a"sheet flow"of water along trench). Intent is to prevent erosion damage. Perforations Plugged. Over%of perforations in pipe are plugged with Clean or replace perforated pipe. debris and sediment. Water Flows Out Top Maintenance person observes water flowing out Facility must be rebuilt or of"Distributor"Catch during any storm less than the design storm or redesigned to standards. Basin. its causing or appears likely to cause damage. Receiving Area Over- Water in receiving area is causing or has No danger of landslides. Saturated potential of causing landslide problems. Internal: Manhole/Chamber Worn or Damaged Structure dissipating flow deteriorates to`/2 or Replace structure to design Post.Baffles,Side of original size or any concentrated wom spot standards. Chamber exceeding one square foot which would make structure unsound. 2005 Surface Water Design Manual—Appendix A A-7 1/24/2005 APPENDIX A MAINT. NCE REQUIREMENTS FOR FLOW CONTROL NVEYANCE,AND WQ FACILITIES NO. 10-CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Component _ _ - Pipes Sediment&Debris Accumulated sediment that exceeds 20%of the Pipe cleaned of all sediment and diameter of the pipe. debris. Vegetation Vegetation that reduces free movement of water All vegetation removed so water through pipes. flows freely through pipes. Damaged Protective coating is damaged;rust is causing Pipe repaired or replaced. more than 50%deterioration to any part of pipe. Any dent that decreases the cross section area Pipe repaired or replaced. of pipe by more than 20%. Open Ditches Trash&Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movEofwater ]Water flows freely through ditches. through ditches. Erosion Damage to See"Detention Ponds"Table No. "Detention Ponds"Table No. 1 Slopes Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design standards. Place or Missing(If the rock lining. Applicable). NO. 11 -GROUNDS (LANDSCAPING) xpected When Results Expected When Maintenance Defect or Problem Conditions When Maintenance is Needed Maintenance is Performed Component General Weeds Weeds growing in more than 20%of the Weeds present in less than 5%of (Nonpoisonous,not landscaped area(trees and shrubs only). the landscaped area. noxious) Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation present in vegetation. landscaped area. Trash or Litter Paper,cans,bottles,totaling more than 1 cubic Area clear of litter. foot within a landscaped area(trees and shrubs only)of 1,000 square feet. Trees and Shrubs Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than 5% .broken which affect more than 25%of the total of total foliage with split or broken foliage of the tree or shrub. limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of injury. knocked over. Trees or shrubs which are not adequately Tree or shrub in place and supported or are leaning over,causing exposure adequately supported;remove any of the roots. dead or diseased trees. I/24/2005 2005 Surface Water Desibm Manual—Appendix A A-9 APPENDIX A MAINTENANCE.RE( CEMENTS FLOW CONTROL,CONVEYANCE, )WQ FACILITIES NO. 22- BAFFLE OIL/WATER SEPARATOR Maintenance Defect Condition When Maintenance is Needed Results Expected When C01,11pOneilt Maintenance is Performed. Vault Area Monitoring Inspection of discharge water for obvious signs Effluent discharge from vault should of poor water quality. be clear with out thick visible sheen. Sediment Sediment depth in bottom of vault exceeds 6 No sediment deposits on vault Accumulation inches in depth. bottom which would impede flow through the vault and separation efficiency. Trash and Debris Trash and debris accumulation in vault Trash and debris removed from Accumulation (floatables and non-floatables), vault,and inlet/outlet piping. Oil Accumulation Oil accumulations that exceed 9 inch,at the Extract oil from vault by vactoring. surface of the water Disposal in accordance with state and local rules and regulations. Vault Structure Damage to Wall, Cracks wider than V2-inch or evidence of soil Vault replaced or repaired to design Frame, Bottom, particles entering the structure through the specifications. and/or Top Slab cracks,or maintenance/inspection personnel determines that the vault is not structurally sound. Damaged Pipe Joints Cracks wider than%2-inch at the joint of any No cracks more than%-inch wide at inlet/outlet pipe or any evidence of soil particles the joint of the inlet/outlet pipe. entering the vault through the walls. Baffles Damaged Baffles corroding,cracking,warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance/inspection person. Inlet/Outlet Pipes Trash and Debris Trash and debris accumulation in inlettoutlet Trash and debris removed from Accumulation (floatables and non-floatables), vault,and inlet/outlet piping. Damaged Pipes Inlet or outlet piping damaged or broken and in Pipe repaired or replaced. need of repair. Access Cover Damaged/Not Cover cannot be opened. Corrosion/deformation Cover repaired to proper working Working of cover, specifications or replaced. Access Ladder Damaged Ladder is corroded or deteriorated,not Ladder replaced or repaired and functioning properly,missing rungs,cracks,and meets specifications,and is safe to misaligned. use as determined by inspection personnel. I/24/2005 2005 Surface Water Design Manual—Appendix A A-I 8 Exhibit H FEMA Map d Q U O L C (0 m N C o�w m N CL C oL E 0 °0 E 7 U 0 T L �j F W co H O V v O O N O= oo sS'. map ON y �ov� m �&Z2 �� W Q g E Z� vo ° oa `e H �-i W WZ- ao E: m v a � " c F Q a � � LLW tc EvoLLJ z Q E'_ M. I.- O N fO j 0 Eago coC.) F ¢ "S wWa. 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