October 29, 2011 Catchment Drainage Area Drainage Area totals 940 - PowerPoint PPT Presentation

Preliminary Results of Hydraulic Analysis October 29, 2011

Catchment Drainage Area • Drainage Area totals 940 acres (286 + 654) • Area circled in red most likely feeds into stream system downstream of 244 th Ave. NE crossing (roughly 250 – 300 acres)

How big of flood was Dec 2010? Using Bear Creek Current and Future Conditions Report (revised) Catchment E16 represents Allen Lake Outflows • 2011 Conditions somewhere in between 1985 and Future conditions. • December 2010 Event had a very rough estimate of 26~28 cfs (+/-) with NE 8 th overtopped by about 18 inches • For this study used range of 26 to 30 cfs for December 2010 event which is approximately a 10- to 25-year event hedging towards future conditions, given 1985 is 25 years in the past.

Allen Lake Elevations* Road Closes** NE 8 th St. Source: Burton *Elevations are approximations **Theoretically at 1-ft deep

Stream Alignment of Study Area • Approximately 5500 feet of stream length between NE 8 th St. and 244 th Ave NE

Modeled Existing Conditions • Bottom of Sediment shown in Red, muck can be > 3 ft deep • At 27 cfs, NE 8 th Street overtops approximately 18 inches • At 30 cfs, NE 8 th Street overtops approximately 24 inches Elevation (ft) 325 330 335 340 345 350 0 634 634 Humphrey 755 755 Humphrey 862 D.S. side of 24... 935 244th Ave NE CP 935 - 2... 1103 1103 - Open Space 1337 1337 - Open Space 1000 1607 1607- Begin new survey Ope... 1975 1975 - Last XS of 1995 Open Space 2335 2335 Hanley 2000 2525 2525 Mertens Allen Lake Feasibility Study 2011 Plan: 1) ExistingOct31 10/26/2011 2) ExistBottomSed 10/27/2011 2665 2665 Christensen 2718 247th Ave Pl CMP 247th Ave NE (Pipe Arch 77x... 2790 2790 MSPT LLC 2850 2850 Copy of 2892 MSPT LLC 2931 2931 NE 18th Street MSPT LLC 3034.25 3034 Floyd 3180 Floyd 3263 3235 Floyd RIVER-1 Reach-1 3000 3505 3505 Floyd Main Channel Distance (ft) 3895 3895 Ciliberti 3955 3955 - Ciliberti 4355 4335 Ciliberti 4000 4522 Syn. 4667 Ciliberti 4667 4667 - Old Survey Lidar right bank Ciliberti 4715 Culvert 4715- (3' Pipe) - Vitale 4785 4785 - Old Survey Michelman 4944 Syn. channel similar to 5073 Michelman 5073 New Survey - Top of Sediment Michelman 5125 5125 - Old Survey Reimer 5265 5265 - Old Survey Reimer 5370 Reimer 5417 Culvert 5417- (3' Pipe) - Roome / Reimer 5000 5497 5497 - copy of 5503 Newfeld 5573 5573 - Newfeld 5640.54* Newfeld 5696.18* Newfeld 5751.81* Newfeld 5807.45* Roome 5891 Lucarelli 5969 U.S. of Footbridge Lucarelli 6051 Lucarelli 6148 Lucarelli 6212 McCoy 6272 McCoy 6337.33* McCoy 6391.16* McCoy 6442.66* McCoy 6000 6503 6547 NE 8th Street NE 8th Street (Culvert 18" and 30") 7000 WS 30 cfs - ExistBottomSed WS 30 cfs - ExistingOct31 Ground Ground Legend

Existing Conditions Flooding Allen Lake Feasibility Study 2011 Plan: Existing Conditions 2011-10-31 10/26/2011 6576 Legend 6355.66* WS 30 cfs Newfeld 6272 6148 Ground 6051 Bank Sta 5980 Ineff 5891 5807.45* Ground 5696.18* Levee 5587 5503 5464 Reimer / Roome 5427 5265 Michelman 5106 5125 4944 4811 Vitale 4785 4725 4667 4522 4355 3995 3955 3505 3263 3180 2665 3034.25 NE 18 th St. 2972 2525 2335 2892 2699 2689 1975 247 th Ave NE 1607 634 1337 1103 1012 244 th Ave NE 862 510 788.* 755

Elevation (ft) 334 336 338 340 342 344 346 Effect of Early Action Existing Conditions & Culverts Partial Blocked 4355 4335 Ciliberti 4000 4522 Syn. 4667 Ciliberti 4667 4667 - Old Survey Lidar right bank Ci... 4705 4705 -Vitali, Old Survey Ciliberti Allen Lake Feasibility Study 2011 Plan: 1) ExistingOct31 10/26/2011 2) Early Action 10/27/2011 4785 4785 - Old S... 4944 Syn. channel similar to 5073 Mich... 4500 5073 New Survey - Top of Se... 5095 Culvert 5095- (3' Pipe) - Michelman RIVER-1 Reach-1 5265 5265 - Old Survey Reimer 5370 Reimer Main Channel Distance (ft) 5407 5407 - Reimer/ Roome, (d.s. 36" CMP) 5447 5447 - Old Survey Newfeld 5497 5497 - copy of 5503 Newfeld 5000 5541 5541 - Newfeld 5573 5573 - Newfeld 5604.5* Newfeld 5640.54* Newfeld 5677.63* Newfeld 5714.72* Newfeld 5751.81* Newfeld 5788.90* Roome 5826 Lucarelli 5891 Lucarelli 5969 U.S. of Footbridge Lucarelli 5500 6051 Lucarelli 6148 Lucarelli 6212 McCoy 6272 McCoy 6319 McCoy 6355.66* McCoy 6391.16* McCoy 6425.5* McCoy 6459.83* McCoy 6000 6503 6547 NE 8th Street NE 8th Street (Culvert 18" and 3... Action Early Existing WS 30 cfs - ExistingOct31 WS 30 cfs - Early Action Legend Ground over the road) lower flows (but not backwater NE 8 th at channel will • High point in significantly blocked. below are not up to and exiting conveyances leading on channel • This is predicated inches to < 6 inches reduces from 24 over NE 8 th St culverts, water depth • Remove blockage in

Clearing channel vegetation is secondary in effectiveness because water can go overbank 900 feet upstream Newfeld farm bridge Allen Lake Feasibility Study 2011 Plan: 1) ExistingOct31 10/26/2011 2) Early Action 10/27/2011 Allen Lake Feasibility Study 2011 Plan: 1) ExistingOct31 10/26/2011 2) Early Action 10/27/2011 5573 - Newfeld .055 . .055 .055 . .08 350 0 350 0 Legend Legend 5 8 WS 30 cfs - ExistingOct31 WS 30 cfs - ExistingOct31 WS 30 cfs - Early Action WS 30 cfs - Early Action Ground Ground 348 348 Bank Sta Ineff Bank Sta 346 346 Elevation (ft) Elevation (ft) 344 344 342 342 340 340 338 338 0 200 400 600 800 1000 0 100 200 300 400 500 600 700 800 Station (ft) Station (ft)

Low flow backwater conditions Elevation (ft) 336 338 340 342 344 4800 5370 Reimer 5407 5407 - Reimer/ Roome, (d.s. ... 5427 5427 - Reimer/ Roome, (36" C... 5447 5447 - Old Survey Newfeld 5464 Newfeld 5497 5497 - copy of 5503 Newfeld 5000 5526 Newfeld 5573 5573 - Newfeld 5604.5* Newfeld 5622 Newfeld 5640.54* Newfeld Allen Lake Feasibility Study 2011 Plan: 1) ExT opSedObstrct 10/25/2011 2) Ex2011TOS2drive 10/25/2011 5659.09* Newfeld 5677.63* Newfeld 5696.18* Newfeld 5200 5714.72* Newfeld 5733.27* Newfeld 5751.81* Newfeld 5770.36* Roome 5788.90* Roome 5807.45* Roome 5826 Lucarelli RIVER-1 Reach-1 5891 Lucarelli 5400 5969 U.S. of Footbridge Lucar... 6051 Lucarelli Main Channel Distance (ft) 5600 6148 Lucarelli 6212 McCoy 6272 McCoy 5800 6319 McCoy 6337.33* McCoy 6355.66* McCoy 6374 McCoy 6408.33* McCoy 6425.5* McCoy 6459.83* McCoy 6000 6503 6547 NE 8th Street NE 8th Street ... 6200 6400 High Point Soft Sediment overtopping. NOT the cause of conditions, but low flow lake levels during locally controls under NE 8 th St, back up culverts deposition will in soft sediment (WSEL of 341 ft) A local high point

Existing, Early Action, Dry NE 8 th St. Elevation (ft) 325 330 335 340 345 350 0 634 634 Humphrey 755 755 Humphrey 862 D.S. side of 24... 935 244th Ave NE CP 935 - 2... 1103 1103 - Open Space 1337 1337 - Open Space 1000 1607 1607- Begin new survey Ope... Allen Lake Feasibility Study 2011 Plan: 1) ExistingOct31 10/26/2011 2) Early Action 10/27/2011 3) DryNE8thSt 10/27/2011 1975 1975 - Last XS of 1995 Open Space 2335 2335 Hanley 2000 2525 2525 Mertens 2665 2665 Christensen 2718 247th Ave Pl CMP 247th Ave NE (Pipe Arch 77x... 2804 MSPT LLC 2892 2897 Merged old survey, new, and LiDAR MSP... 2948.75 NE 18th St CMP NE 18th St (Pipe Arch 77x52) 3034.25 3034 Floyd 3180 Floyd 3263 3235 Floyd RIVER-1 Reach-1 3000 3505 3505 Floyd Main Channel Distance (ft) 3895 3895 Ciliberti 3955 3955 - Ciliberti 4355 4335 Ciliberti 4000 4522 Syn. 4667 Ciliberti 4667 4667 - Old Survey Lidar right bank Ciliberti 4730.5 4730 -Old Survey Ciliberti 4811 Syn. Lidar left bank, 5073 right bank, no sedime... 4944 Syn. channel similar to 5073 Michelman 5073 New Survey - Top of Sediment Michelman 5265 5265 - Old Survey Reimer 5370 Reimer 5435 5435 - Old Survey Newfeld 5000 5497 5497 - copy of 5503 Newfeld 5573 5573 - Newfeld 5640.54* Newfeld 5714.72* Newfeld 5788.90* Roome 5891 Lucarelli 5969 U.S. of Footbridge Lucarelli 6051 Lucarelli 6148 Lucarelli 6212 McCoy 6319 McCoy 6391.16* McCoy 6459.83* McCoy 6000 6547 NE 8th Street NE 8th Street (Culvert 18" and 30") Existing Early Action Dry NE 8th 7000 WS 30 cfs - ExistingOct31 WS 30 cfs - DryNE8thSt WS 30 cfs - Early Action Legend Ground

Summary  Causes of NE 8 th overtopping, are a combination of:  Partial culvert blockages and sediment filling in  Low gradient (slope) of stream system  Culvert capacities  Vegetation reducing stream conveyance capacity  Existing Conditions (at 30 cfs)  Greater than 1.5 ft water over NE 8 th St.  Sheet flows over Vitale driveway,  A few inches over Michelman’s ,  An inch or so over Reimer/Roome,  Not overtopping Newfeld  December 2010 event was approximately a 10 to 25 year event in magnitude.

Summary Proposed Early Actions Make NE 8 th dry for that size of event (aka Dry NE 8 th St.) Results: NE 8 th is dry ( barely! ) for Results: Less than 6 inches over that size event NE 8 th for that size event  100 year overtops a few inches  future 100-yr (39 cfs) overtops NE 8 th approx. 1.5 ft, Results are preliminary.