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TECHNICAL MEMORANDUM HOOSIC RIVER FLOOD CONTROL CHUTE STRUCTURAL ASSSESSMENT APRIL 30, 2010 PAGE 1

TECHNICAL MEMORANDUM

Hoosic River Flood Chute Naturalization Structural Assessment of Flood Control Chutes

North Adams, MA Milone & MacBroom, Inc.

MMI #2688-21-1 April 30, 2010

1.0 INTRODUCTION

The Massachusetts Department of Fish and Game’s Division of Ecological Restoration has retained Milone & MacBroom, Inc. to determine the structural condition of the existing concrete flood control chutes located in North Adams, Massachusetts and to assess if the flood walls can be modified without impacting the integrity of the adjacent walls, the chute floor or opposing walls. The modification to the flood control chutes is proposed as part of a plan to improve water quality of the river, bring back aquatic habitat and provide a public connection to river. The U.S. Army Corps of Engineers (ACOE or the Corps) is assisting the Town of North Adams in the analysis of restoration alternatives. The Hoosic River flood control project was built in the 1950s after several devastating floods. It features rectangular concrete channels known locally as "chutes," as well as a trapezoidal riprap channel. The flood control project was constructed prior to modern environmental and social policies regarding river management. The rectangular concrete "chute" channel has high velocity, no natural substrate, and little shade, resulting in shallow warm water conditions that are unsuitable for aquatic habitat. The channel has no recreational or aesthetic value. This memorandum contains a description of existing structural conditions of the flood control chutes and describes possible structural modifications that would maintain the structural integrity of the system.

2.0 EXISTING CONDITIONS 2.1 Flood Chute Configuration

The North Adams flood control structure contains two sections. The first section, and the longest, is along the North Branch of the Hoosic River. The structure begins at the Eclipse Mill Dam and continues downstream approximately 1.3 miles to the confluence with the South Branch of the Hoosic River. This section of the chute is a three sided cast-in-place concrete structure with a width between walls of 45 feet. The second section is along the South Branch of the Hoosic River. The structure begins adjacent to Joe Wolfe Field and continues approximately 0.8 miles to the confluence with


the North Branch of the Hoosic River. This section of the chute is a three sided cast-in-place concrete structure with a width between walls that varies from 65 feet to 45 feet. After the confluence of the two branches, the flood control chute continues 1,200 feet downstream. This section of the chute is a three sided cast-in-place concrete structure with a width between walls of 110 feet. At the end of the chute, there is a full width parabolic apron and a depressed stilling basin to decrease flow velocities before returning to the existing river channel. On horizontally curved sections of the chute, the bottom slab is super elevated to minimize wave formation and to reduce energy losses. Base plans of the structures were created using satellite images and superimposing the approximate location of the original construction baseline along with stationing. An Overview plan of the entire area and enlarged plans of the north and south branch structures are provided in Appendix A.

2.2 Flood Chute Structural Condition

A visual inspection of the flood chutes was performed on April 8, 2010 by two structural engineers Glenn Jarvis, P.E. and Fredrick Wilson, E.I.T. of Milone & MacBroom, Inc. Overall, the concrete flood control structure is in fair condition, with a majority of observed deterioration occurring in the bottom invert slab. Photographs taken during the inspection and referenced below are provided in Appendix B. The following general conditions were observed: ! Bottom invert slab contains moderate wear with exposed aggregate visible within

limits of normal water flow. (See photo No. 4) ! Bottom invert slab contain eight 6-inch diameter circular core holes per 24-foot long

section of slab. Most of the holes showed groundwater seepage and concrete deterioration and/or spalling at the downstream edge. (See photo No. 5)

! The bottom invert slab has numerous transverse cracks. (See photo No. 24) ! The bottom invert slab has spalls at transverse construction/expansion joints. (See

photo No. 23) The following conditions were seen at specific locations:


North Branch STA 200+80 Large spall at top of north wall at expansion joint. Copper water stop is

exposed. (See photo No. 7 & 8) STA 199+90 Horizontal cracking with efflorescence at top of north wall above drainage

outlets. (See photo No. 6) STA 195+70 3-foot by 3-foot sinkhole in back of north wall directly above drainage

pipe. (See photo No. 11 & 12) STA 179+60 75 feet of north wall tilting toward channel by up to six inches at the top.

Trees approximately 6-inch diameter overhang the wall by up to 10 feet. The adjacent 50 feet of wall to the east looks like it was replaced recently. (See photo No. 13 through 16)

STA 172+30 Small sinkhole 1-foot by 1-foot at northwest corner of Eagle Street Bridge.

30-inch corrugated metal drainage pipe directly below. (See photo No. 19) STA 171+50 24 feet of north wall tilting toward channel by up to two inches at the top.

(See photo No. 20 & 21) STA 167+00 Heavy vegetation growth overhanging north wall. (See photo No. 25) STA 165+50 Unexpected turbulence in flow near south wall. Possible hole or slab

settlement. (See photo No. 26) STA 156+50 Spall at expansion joint at south wall near Marshall Street Bridge. Copper

water stop exposed. (See photo No. 27) STA 152+40 New 30-foot long section of north wall recently replaced (2009) after

failure. (See photo No. 28 & 29) STA 138+00 Bottom slab shows multiple transverse and longitudinal cracks with to 142+00 spalling. (See photo No. 32 & 34) STA 137+00 Vertical cracks in Brown Street bridge wingwall. (See photo No. 35) STA 135+80 Large spalls at expansion joint in bottom slab. Spall approximately 1-foot

wide by 1-foot deep. Slab may have void beneath due to water flow. Reinforcing steel is also exposed over 20 feet long near north wall. Turbulence noted just downstream of joint near south wall. (See photo No. 36 through 40)


South Branch STA 160+00 Heavy scaling of bottom slab. Active weep holes and heavy vegetation at

east wall. (See photo No. 45 & 46) STA 162+50 Spall in bottom slab with exposed reinforcing steel. Also turbulence may

indicate additional spall or settlement. (See photo No. 47 through 49) STA 185+50 Large spall in east wall at expansion joint with exposed reinforcing steel

and water stop. Spall is approximately 10 feet high by 16 inches wide by 8 inches deep. W. wall section south of joint is tilting towards channel 4 inches at the top. (See photo No. 50 through 53 & 57 through 59)

STA 184+50 Sediment build up at face of east wall approximately 150 feet long. (See

photo No. 60)

2.3 STRUCTURAL MODIFICATIONS

Information for design of the flood control chute side walls was located in the Corps report entitled Definite Project Report – Basis of Design – Volume II, Appendix D – Structural Design. The calculations show only the concrete dimensions of the wall and the stability analysis – that is, the overall overturning and sliding of the wall section. Three types of walls were designed; an “L” wall (figure D1 & D2), an “L” wall with railroad surcharge (figure D3 & D4) and a “T” wall (figure D6 & D7). Copies of the existing structural design calculations and descriptions are included in Appendix C. The following findings and recommendations are offered: 1. A visual inspection of the north and south branches of the Hoosic flood chute reveals

that it is in fair condition, with visible cracks, spalling, sinkholes, and potential failures. These deteriorations are generally minor and the chute does not appear to be in immanent danger of failing.

2. Individual deficiencies can be corrected without a large-scale overhaul of the chute

system. 3. From a structural point of view, it appears to be possible to modify the height of the

existing walls to accommodate alternate channel configurations if the hydraulic performance is maintained. The walls can be lowered in specific areas without impacting the integrity of adjacent walls, the chute floor or the opposing walls. The area behind the lowered wall could be lowered to create additional floodplain and also allow for recreational uses.


4. Another structurally viable modification would be to create a low flow channel in the center of the existing chute. Currently, the original design calculations show that the center section of the bottom slab is separate from the side wall footings. This will allow the removal of the existing slab and the construction of a “low flow” channel. Do to the extremely high velocities during high flow; the bottom of the low flow channel would require a 2 foot thick structural concrete slab that would match into the top of the existing flood wall footing. (See sketch below.)

5. Areas behind the flood walls can be planted with trees to provide shading of the channel; however the trees should be placed far enough away to prevent root damage of the walls.

6. Large portions of the existing flood control chute are directly adjacent to buildings and roadways. In theses areas no modifications to the chute walls will be possible unless the properties are purchased and the buildings removed. The wall may be supporting soils that are under the influence of the building load.

7. The modification of the wall height was analyzed using the computer program REST

2.0. The wall was run with the top 4 feet removed and was found to be stable in respect to overturning and sliding. Structural analysis of the wall reinforcing was not done as no plans were found which showed the reinforcing size and spacing.

8. The one caveat that we have is that the analysis was done in July of 1945 and the

plans that we obtained were dated July 1954, so there is a possibility that the original design could have changed. We recommend that further research be done to obtain a more complete set of as-built plans of the flood control chute.

APPENDIX A

Project L

imit

Project Limit

Project Limit

210+

00

208+

00

209+

00207+

00

211+

00130+00

142+

00

131+00

135+

00

140+

00137+

00

139+

00

136+

00

138+

00

132+00

206+00

182+00

184+00

141+

00

133+00

183+00

185+00

205+00

203+00

1 inch = 500 feetOverview Map

Project Limit

130+00

142+

00

131+00

135+

00

140+

00

137+

00

139+

00

136+

00

138+

00

132+00

134+00

141+

00

133+00

145+00

146+

00

143+

00

144+00

143+

00

145+

00

144+

00

1 inch = 100 feetMap 1 Hoosic River

152+

00151+

00

145+00

150+

00

159+00

149+

00

153+

00

147+

00

156+00

146+

00

148+

00

144+

00

158+00

157+00

155+00

154+00

147+

00

148+

00

152+

00

154+00153+

00

146+

00

145+

00

149+

00

156+00

151+

00150+

00 157+00155+00

1 inch = 100 feetMap 2 Branches End

176+00

163+

00

165+

00

170+

00

173+

00

169+

00

166+

00

161+

00

162+

00

164+

00

174+

00

160+

00

172+

00

168+

00167+

00

171+

00

175+00

159+00

177+00

179+00

178+00

1 inch = 100 feetMap 3 North Branch Hoosic River

179+00

176+00

178+00

180+00

194+00

186+

00

196+00

195+00

199+00

191+00181+00

197+00

193+00

192+00

200+00

198+00

188+00

185+

00

187+00

190+00

177+00

182+00

183+

00

189+00

184+

00


Project

Limit

214+

00213+

00

215+

00

211+

00

212+

00

216+

00

210+00209+00

208+00207+00

204+00

203+00

206+00

205+00

201+00

202+00

199+00

200+00


174+00

159+00

172+00

173+00

168+00

166+00

160+00

170+00

165+00

167+00

158+00

161+00

164+00

157+00

163+00

169+00

171+00

162+00

1 inch = 100 feetMap 6 South Branch Hoosic River

Project Limit

182+00

184+00

183+00

185+00

181+00

178+00

174+00

179+00

180+00

177+00

176+00

175+00

1 inch = 100 feetMap 7 South Branch Hoosic River

APPENDIX B

PROJECT NO.: 2688-21

STRUCTURE: Concrete Levee

TOWN: North Adams, MA PHOTO LOG

CARRIED/CROSSED: Hoosic River

SHEET NO.: 1 OF

DATE: April 08, 2010

REPORT PHOTO NO. PHOTO DESCRIPTION

01 Concrete spalling/channeling at locations of change in super elevation and drainage outfalls. Moss cover evident.

02 Concrete spalling/channeling at locations of change in super elevation and drainage outfalls. Moss cover evident.

03 Typical spalling concrete at joint between wall and slab. Typical weep holes in wall.

04 Heavy scale and spalling concrete in slab and slab joints along super elevated sections. Moss build-up evident.

05 Typical holes in slab - appears to be (8) per slab section. It was noted that in areas with constant water movement, spalling at hole locations is typical.

06 Longitudinal wall cracking above drainage outfalls. Heavy vegetation growth along back of wall.

07 Wall joint failing - waterstop visible. Seepage through the joint is evident. Water is actively overtopping the wall.

08 Wall joint failing - waterstop visible. Seepage through the joint is evident.

09 The adjoining grade is overtopping the existing wall and being held back by the attached chainlink fence. Vegetation overtopping the wall has been maintained, but not removed.

10 Scale and spalling concrete at the secondary dam.

11 Sinkhole forming behind the levee wall directly above a drainage outfall.

12 Drainage outfall below sinkhole in photo number 11. No sign of infiltration point visible.

13

Wall panel appears to be separating - top of panel overturning. Vegetation has not been removed and is cantilevering over the top of the wall. Four wall panels (min.) appear to be effected.

14 Panel referenced in photo number 13. Approximately 1" separation at top of wall.

15 Panel referenced in photo number 13. Approximately 4" separation at top of wall.

16 Panel referenced in photo number 13. Approximately 5"-6" separation at top of wall.

17 Panel referenced in photo number 13. Approximately 5"-6" separation at top of wall.

18 Location for change in super elevation resulting in water build-up and turbulence. Possible location for slab/wall degradation.

19 Sink hole forming on the northwest corner of the Eagle St. Bridge wingwall (Lopandos Liquor store parking). 30" CMP outfall in levee wall beneath sink hole.

20 Wall panel separation (approx. 1").

21 Wall panel separation (approx. 1"). Joint filler is exposed at the face of the wall. Top of wall is cracking along the fence line.

22 30" CMP outfall at the Eagle St. bridge (sinkhole noted above in photo number 19). Heavy scale and spalling concrete noted below outfall.

23 Heavily spalled slab concrete (two locations visible - more noted beneath the water). Possible slab infiltration point.

24 Transverse slab cracking (typ.)

25 Heavy vegetation growth along the back of the north wall. Overtopping wall.

26 Unexplained water turbulence. Possible settlement or cracking in slab.

27 Joint failing - weather stop is exposed.

28 Replace wall section from car wash driveway. Approx. 72 LF of chain link fence was replaced.

29 Repaired wall section and new chain link fence from inside levee. Existing joint was retained but concrete was poured over the top of the joint.

30 New aluminum fence beyond replaced wall section. Fence is attached to back of wall.

31 Top of wall cracking.

32 Slab degradation just beyond joining of north and south levees. Joints and transverse cracking heavily spalled.

33 Slab degradation just beyond joining of north and south levees. Joints and transverse cracking heavily spalled. Moss build-up.

34 Slab degradation just beyond joining of north and south levees. Joints and transverse cracking heavily spalled. Moss build-up.

35 Cracking in wall beneath Brown St. Bridge.

36 Heavy loss of concrete in slab along transverse joint. Steel exposed.

37

Heavy loss of concrete in slab along transverse joint. Steel exposed. Moss build-up. Turbulence noted along south wall indicating possible slab cracking or settlement.

38 Turbulence noted along south wall indicating possible slab cracking or settlement.

39 Heavy loss of concrete in slab along transverse joint. Weather stop and reinforcing steel exposed.

40 Heavy loss of concrete in slab along transverse joint beneath water.

41 South Branch levee - looking south.

42 South Branch levee - looking north.

43 Previous repairs made to levee wall.

44 Typical loss of concrete along transverse cracks.

45 South branch facing north (from West Main St. Bridge).

46 Active wall weep holes. Heavy scale along channel bottom.

47 Water turbulence indicates possible slab cracking or settlement.

48 Spalled concrete from slab exposing reinforcing bars.

49 Water turbulence indicates possible slab cracking or settlement.

50 Joint failure - loss of concrete and exposed weather stop/reinforcing bars.

51 Joint failure - loss of concrete and exposed weather stop/reinforcing bars. Area of loss is approx. 10' high by 16" wide. The wall panel appears to be separating.

52 Joint failure - exposed weather stop and 1" reinforcing bar.

53 Joint failure - loss of concrete and exposed weather stop/reinforcing bars. Area of loss is approx. 10' high by 16" wide by 8" deep. The wall panel appears to be separating.

54 Start of south branch facing downstream.

55 Slope protection at start of south branch (west side).

56 Slope protection at start of south branch. Vegetation along banks.

57 Panel separation at joint failure noted in photo numbers 50-53. Separation is approx. 3".

58 Panel separation at joint failure noted in photo numbers 50-53. Separation is approx. 3".

59 Joint failure mentioned in photo numbers 50-53 as seen from west wall.

60 Sediment build-up along east wall at start of south branch. Build-up extends approx. 150 feet into the structure.

99 Realty DriveCheshire, CT 06410(203) 271-1773 Fax (203) 272-9733


!

!

MEMORANDUM

TO: Judith Grinnell – HOORWA

DRAFT FROM: James G. MacBroom, P.E.

Milone & MacBroom, Inc. (MMI)

DATE: April 5, 2012

RE: Hoosic River Revival Project

Phase II, Stage I Options Assessment

MMI #4195-03

1.0 Introduction

MMI is currently proceeding with further evaluation of the Hoosic River in North Adams,

Massachusetts to address potential restoration and revitalization options. This memo discusses Task

1.3 of the scope of work concerning Hurricane Irene, design flow criteria, and relation to climate

change. Following review and discussion, this information will be incorporated into the overall

technical report.

2.0 Hurricane Irene at North Adams, Massachusetts

The powerful floods caused by Hurricane Irene are a timely reminder about the need for adequate

channel capacity in North Adams. Regional rainfall ranged from five to eight inches in about 12

hours. Many stream gauging stations in the Northeast recorded peak flows at or above that of a once-

in-100-years frequency. Locally, the Hoosic River U.S. Geological Survey stream flow gauge in

Williamstown (#01332500) recorded a peak flow of 12,900 cfs on August 28, and the South Branch

gauge in Adams (#01331500) had 2,100 cfs. Most of the water measured at Williamstown was

apparently from the North Branch of the Hoosic River, despite its smaller watershed, due to uneven

precipitation.

Milone & MacBroom, Inc. (MMI) has used the measured peak flows at the two USGS gauges and

adjusted them to estimate the corresponding peak flows on the South and North Branches in North

Adams. The flow rates were then compared to previously prepared statistical analysis by MMI (June

2010) to estimate flood recurrence frequencies.

Hurricane Irene Flood Flow Data

Location Peak Flow

Rate, cfs Comments

Estimated Frequency,

Years

% of Corps

Design Flow

South Branch gauge 2,100 USGS Data 10 years N/A

South Branch chute 2,917 Estimated 10 years 35.6

Main Branch 12,900 USGS Data 50 years 53.0

North Branch 9,242 Estimated 50 years 61.6

Hoosic River Revival Project

April 5, 2012

Page 2

The peak flows from Hurricane Irene are compared with other floods measured by USGS in the table

below. Note that on the North Branch, Irene is the second largest known flood and is also the second

largest on the Main channel. But on the South Branch, it is ranked at number seven.

Flood History at USGS Gauges

Location Date Peak Flow Period of Record

North Branch

#01332000

D.A. = 40.9

Nov. 1927

8/28/2011*

9/21/38

8/10/76

4/5/87

12/31/48

3/18/36

12,200

9,242*

8,950

8,450

6,720

6,300

6,100

1928-1990

Main Channel at

Williamstown

#01332500

D.A. = 126 sm

12/31/48

8/28/2011*

Nov. 1927

8/10/76

11/26/50

10/8/05

4/5/87

12/21/73

13,000

12,900*

12,400

11,200

10,800

9,820

9,350

8,690

1927, 1941 - Present

South Branch at

Adams #01331500

D.A. = 46.7 sm

9/21/38

3/18/36

12/31/48

8/10/76

10/9/05

4/5/87

8/28/2011*

5,080

3,670

3,100

2,720

2,340

2,200

2,100*

1931 - Present

*Hurricane Irene

Photographs taken during Hurricane Irene provided by HOORWA and post-flood photographs of

high water marks show that the North Branch and Main channels were flowing more than half full

consistent with hydrology data, while the South Branch chute was only about a third full.

There was moderate flood damage on a regional basis but, locally, it had a severe impact on those

who were directly affected. The southbound lane of Route 8 in Clarksburg was destroyed, several

local roads were inundated (West Shaft Road, Ashland Street, Church Street), and numerous people

were evacuated in Adams. In downstream Williamstown, the Spruces Mobile Home Park had a

partial evacuation due to flooding and portions of Routes 7 and 42 closed. Severe infrastructure

damage, including landslides, occurred along Route 2 to the east, in southern Vermont, and both the

Catskill and Adirondack Mountain areas of New York. North Adams was fortunate not to have

greater damages.


April 5, 2012

Page 3

Hurricane Irene is one of the largest flood events recorded in the Hoosic River basin over the past

80± years and, yet, the chutes were only two-thirds full, providing a 50% reserve. The original U.S.

Army Corps of Engineers (USACE) design criteria has stood the test of time and has been adequate.

Some rivers in Vermont and New York had floods with an estimated frequency of once in 500 years,

which would have required use of the freeboard capacity.

Hurricane Irene - North Branch chute High water marks after Hurricane Irene.

flowing at over half full.

3.0 Design Flows

Flood control and river restoration projects are normally evaluated for one or more stream flow rates

that are used to calculate water elevations and the size of required channels, bridges, and dams. Flow

rate may also be used to assess the more frequent events, to assess fish passage, habitat

characteristics, sediment transport, water quality, and recreational values. The maximum specific

flow rate used to assess flood control projects is often called the flood design flow.

The North Adams flood control project along the South Branch, North Branch, and Main Hoosic

River channels was designed and built by the USACE. The flood design flows were based upon

actual floods and include large "safety factors" that vary in each channel. The USACE design flows

were summarized by MMI in a June 2010 report and are compared to Hurricane Irene below.

Peak Flow Rates, CFS

Main Stem North Branch South Branch

1946 USACE Design Flow 24,300 15,000 8,200

1981 FEMA, 100 year 16,550 11,800 7,228

2010 MMI, 100 Year 13,557 11,184 7,678

2011 Hurricane Irene* 12,900 9,242 2,917

*Estimated from USGS gauging stations

Project sponsors (communities, agencies) select their flood design criteria based upon standard

engineering recommendations, the level of risk, and practical considerations such as cost,


April 5, 2012

Page 4

environmental impact, and need for land acquisitions. As projects proceed from early planning

phases to design, risk assessments are often performed to compare multiple design flood criteria

versus risk and cost. While larger design criteria reduce risk, such projects often have larger impacts

and are not implemented.

In many cases, the flood design criteria are mandated by state or federal regulatory agencies or by the

programs that provide funding. For example, FEMA requires use of the 100-year frequency flood.

4.0 Climate Change

The earth's climate is continuously changing. The planet is currently in a warming phase that began

about 20,000 years ago and which included the recession of continental glaciers from the United

States about 12,000 years ago. Climate change should be considered during discussions on potential

design criteria for all infrastructure. The Massachusetts Office of Energy and Environmental Affairs

(OEEA) has issued a September 2011 report on Climate Change Adaptation to address strategies for

climate change. OEEA predictions, based on national data, are that precipitation is likely to increase

5% to 8% by 2050 and 7% to 14% by 2100.

A review of long-term stream flow data at the Hoosic River gauge in Williamstown does not reveal

any distinct pattern. However, some regional precipitation and stream flow stations do indicate a

slight but steady increase. The National Oceanographic and Atmospheric Administration does

recommend considering climate change for project design due to increases in peak flow rates at most

regional stream gauges.

5.0 Summary

Hurricane Irene was a major flood event that set long-term records at many regional gauging stations.

Along the main Hoosic River in Williamstown, it is the second highest known flood, equal to about

one-half of the USACE design flow. The USACE criteria, set in 1946, still appears to be adequate

and quite conservative.

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