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Article 25 - MA03104 Old Shepard St Dam Canton Design Report - Signed
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Source page 81
Old Shepard Street Dam, NID No. MA03104 SA Project No. 052-15-022
Canton, MA Stephens Associates Consulting Engineers, LLC
Stability Evaluation - Spillway
Calculation: Calculate the wall stability based on assumption of monolithic structure
Assume: Calculation for stability per foot of wall.
Soil stresses and lateral earth pressures
Top Backfill Total Pore Effective Rankine Effective Horizontal Earth Pressures (psf)
Layer Elevation Thickness Stress Pressure Stress Active At-Rest Passive
Layer Number (feet) (feet) (psf) (psf) (psf) Top Bottom Top Bottom Top Bottom
Back of Wall/Dam:
Soil 1B 107 6 406 406 0 0 85 0 123 0 601
Rock 2B 101.0 0.0 1006 780 226 85 85 123 123 601 601
At Wall Bottom 101.0 1006 780 226 85 56 90 90 908 908
At Water Table El. 113.5 0 0 0 0 0 0
Front of Wall/Dam:
Rockfill 1F 105 4 25 25 0 0 85 0 124 0 1072
Rock 2F 101.0 0.0 565 275 290 79 79 124 124 1072 1072
At Wall Bottom 101.0 565 275 290 72 72 116 116 1168 1168
At Water Table El. 105.4 0 0 0 0 0 0
116 Wall Back 116 116 Wall Back 116
Wall Back
Wall Back - Active
Wall
114 Wall Front 114 Wall Front 114 Front
114
0 0 0 Wall Front - Passive
0
112 112 112 Wall Back - At rest
112
Wall Front - At Rest
110 110 110
Elevation (ft.)
110
Elevation (ft.)
Elevation (ft.)
Elevation (ft.)
108 108 108
406
108
406 0
0
106 106 106
0
25 25 0 106
0
104 104 104 0 0
104
102 102 102
565 1006 275 780 290 226 102
100 100 100 85
90116
124
123 1072 1168
0 500 1000 1500 0 1000 2000 0 1000 2000
100
Total Stress (psf) Porewater Pressure Effective Stress (psf) 0 200 400 600 800 1000 1200 1400
(psf)
Horizontal Effective Stress (psf)
Select Lateral Earth Pressure NOTES FOR INPUT:
Earth Pressure type: 0= At-rest In front of Dam To select type of lateral earth pressure (LEP) used
0= At-rest Behind Wall/Dam in analysis, use A for active, 0 (zero) for at-rest, P
for passive, or N for none.
For passive resistance (Pp), active pressure should
be used on opposite side and Rp may be used to
Reduction factor (Rp) for Passive Resistance (Pp): 1.00 account for strain incompatibility with mobilization
NOTE: For full passive resistance reduction factor (Rp) = 1 of active stress.
Page 5 of 13Source page 82
Old Shepard Street Dam, NID No. MA03104 SA Project No. 052-15-022
Canton, MA Stephens Associates Consulting Engineers, LLC
Stability Evaluation - Spillway
Calculate Coefficient of Active Pressure for Earthquakes
Massachusetts Building Code uses pre-determined factor of 0.045. AASHTO calculates the coefficient using Mononobe-Okabe.
Method: Other - See separate KAE = #VALUE! (Calc. requires factors below for AASHTO method)
ΔKAE = #VALUE!
This section not used for this analysis. See separate sheet.
A (g) = 0.15 Site acceleration coefficient, selected from Figure 1-5 in AASHTO manual
β (deg.) = 0.0 Batter angle of wall back. See AASHTO manual for definition of positive and negative. Set to zero for Rankine con
θ= Not Applicable for MBC Metho Wall or Dam: Dam Note: For MA Dam Regulations: If Wall, use kh = A/2. If Dam, use kh = A
ψ= Not Applicable for MBC Method
Forces on Wall Per Foot of Wall:
Sign convention: negative is driving force/moment, positive is resisting force/moment.
NOTE: LEP is lateral earth pressure Moment Moment
Force Arm Moment Force Arm Moment
Horizontal: Layer (kips) (feet) (kip-ft) Vertical: (kips) (feet) (kip-ft)
Back LEP above GWT L1:- Fill 0.0 10.3 0.0 Weight of spillway and bridge 36.4 12.9 470.2
Back LEP. below GWT L2:- Fill -0.4 2.0 -0.7 components, and overlying
Back LEP below GWT L3:- Fill 0.0 3.0 0.0 upstream and downstream
Back LEP from Surcharge L4:- Fill 0.0 3.0 0.0 water and soil (refer to Sheet 7)
Water on Back U1h:- Water 0.0 0.0 0.0
Water on Back U2h:- Water -2.3 6.8 -15.4
Water on Base U3h:+ Water 0.0 0.0 0.0
Water on Base U4h:+ Water 0.0 0.0 0.0
Water on Base U4Ch:+ Water
Water on Crest U5h:- Water 0.0 0.0 0.0
Water on Crest U6h:- Water 0.0 0.0 0.0
Water on Front U7h:+ Water 0.0 4.1 0.0
Water on Heel U10:- Water -2.1 2.0 -4.2
Water on Heel U11:- Water -0.5 1.3 -0.7
Water on Toe U12:+ Water 0.1 2.0 0.2
Water on Toe U13:+ Water 0.5 1.3 0.7
Front LEP above GWT L5:+ Soil 0.0 4.3 0.0
Front LEP below GWT L6:+ Soil 0.2 1.3 0.3 Hydrostatic Uplift (refer to -8.2 16.0 -131.2
Front LEP below GWT L7:+ Soil 0.0 0.0 0.0 sheets 7 and 8)
Ice Force on Wall (sheet 9) Ice -4.7 12.0 -56.5
Earthquake (sheet 10 Ew:- Water 0.0 0.0 0.0
Earthquake (sheet 11 Es:- Soil 0.0 0.0 0.0
Earthquake (sheet 7) Ei:- Inertia 0.0 0.0 0.0
Sum Horizontal Forces -9.1 Sum Vertical Forces 28.2
Sum Moments From Horizontal Forces 8.4 -76.4 Sum Moments from Vertical Forces 339.0
Page 6 of 13Source page 83
Old Shepard Street Dam, NID No. MA03104 SA Project No. 052-15-022
Canton, MA Stephens Associates Consulting Engineers, LLC
Stability Evaluation - Spillway
CHECK DESIGN BASED ON BEARING SURFACE OF UNIT THICKNESS OF WALL:
SUM MOMENTS: 262.6 kip-ft (includes 0 reduction due to arch 3-D effects)
Resist. Mom. (+) = W1+W2+W3+W4+W5+W6+W7+W8+U1v+U2v+U3h+U4h+U5v+U6v+U7+U8+U9+U12+U13+L5+L6+L7+A1+A2 = 471.4
Driv. Mom. (-) = L1+L2+L3+L4+U1h+U2h+U3v+U4v+U5h+U6h+U10+U11+Ew+Es+Ice = (includes reduction due to arch 3-D effects) -208.8
Check sum = 262.6
CHECK SAFETY FACTOR AGAINST SLIDING ALONG BASE: Sliding FS RESULT
Resisting Force: 21.22 FS=: 2.3
ESTIMATE CENTROID AND MOMENT OF INTERTIA OF SPILLWAY FOOTING FOR BEARING PRESSURE ESTIMATE:
Moment of inertia about centroid-x:
Componen x, ft z, ft. area, sf CM-x, ft A * CM-x, ft^3 Icm, ft^4 A*d^2, ft^4 ICOMBINED, ft^4
A 11.92 8.0 95 6.0 568 1128 6145 7273
B 11.92 8.0 95 6.0 568 1128 6145 7273
C 9.58 38.5 369 16.7 6165 2824 2733 5557
D 6.92 32.5 225 25.0 5610 896 27059 27955
E 22.50 23.3 523 11.3 5885 22069 3918 25988
F 22.50 8.3 186 11.3 2088 7831 1390 9221
Σarea = 1493 ΣA * CM-x = 20885 ΣIcombined = 83267 ft^4
Centroid-x = 14.0 ft ΣIcombined/length = 1190 ft^4/ft
Resultant = (Σmoments / Σvertical forces) = 9.3 ft Σarea/length = 21 ft^2/ft
e = eccentricity = Centroid-x - Resultant = 4.7 ft
Downstream bridge approach toe
Centroid-x (center of
mass in x-direction
Upstream bridge approach heel
Upstream spillway heel
ESTIMATE FOOTING BEARING PRESSURE:
Bearing Pressure RESULTS y = distance from
Bearing Pressure, ksf
Bearing Pressure = Q/A + M*y/I Location centroid-x, ft.
where: Q = sum of vertical forces = 28.2 kips/ft Downstream bridge approach toe 14.0 2.9
B = footing width = 29.4 ft. Centroid-X 0.0 1.3
e = Centroid-x - (Σmoments / Σvertical forces) = 4.7 ft. Upstream bridge approach heel -8.5 0.4
M = Sum of moments about centroid-x = 131 k-ft/ft Upstream spillway Heel -15.4 -0.4
Page 7 of 13Source page 84
Project: Numbe 052-15-022 Sheet 8 of 13
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject Spillway Stability
Ckd. By: JET Date: November 15, 2016 Weight of Spillway and Bridge Components
Estimate Weight, Forces and Moments of Spillway and Bridge components per linear foot
Convert soil/water/structure weight, forces and moment on spillway and bridge to force/moment per linear foot
Sign convention: negative is driving force/moment, positive is resisting force/moment.
Unit weight for concrete is 0.15 kips/CF Point of rotation for moments is downstream toe of bridge abutments, El. 101 ft.
Unit weight for soil beneath base slab 0.135 kips/CF Assume weight distributed over tributary width of 70 ft
Unit weight for soil above bridge abutment footings 0.135 kips/CF For moments due to horizontal forces, earthquake acceleration is 0.15 g
Unit weight of water 0.0624 kips/CF Downstream water elevation 105.4 ft
Table of Weights and Moments for Spillway and Bridge components
Dimensions, feet M @ d/s toe of
Vol., M due to horiz.
x (dist. from upstream toe of spillway base slab) y (Elevations in NGVD 1929) z (left-right) cubic Weight, bridge abut.
Component Quant. forces in EQ, k-
CM-d/s kips due to vert.
u/s d/s avg width CM-u/s bottom top height CM-y avg depth feet ft
toe forces, k-ft
Pier 32 -44 833
stem - rectangular portion 2 1.5 4.5 3.0 3.0 26.4 105.0 116.8 11.75 110.9 1.5 106 16 -23 419
stem - triangular portion 2 4.5 7.0 1.3 5.3 24.1 105.0 116.8 11.75 108.9 1.5 44 7 -8 159
stoplog bumpout - rect. u/s 4 1.5 2.2 0.7 1.8 27.6 105.0 115.5 10.5 110.3 0.5 14 2 -3 58
stoplog bumpout - rect. d/s 4 2.7 4.5 1.8 3.6 25.8 105.0 115.5 10.5 110.3 0.5 39 6 -8 149
stoplog bumpout - triangular 4 4.5 7.0 1.3 5.3 24.1 105.0 115.5 5.25 108.5 0.5 13 2 -2 47
Spillway abutment 102 -97 2577
stem 2 1.5 8.2 6.7 4.8 24.6 105.0 116.8 11.75 110.9 2 313 47 -70 1155
footing 2 0.0 6.9 6.9 3.5 26.0 101.0 105.0 4 103.0 5.5 304 46 -14 1185
stoplog bumpout - rect. u/s 2 1.5 2.2 0.7 1.8 27.6 105.0 115.5 10.5 110.3 0.5 7 1 -1 29
stoplog bumpout - rect. d/s 2 2.7 8.2 5.5 5.4 24.0 105.0 115.5 10.5 110.3 0.5 58 9 -12 208
Base slab 238 -84 4952
slab 1 0.0 17.5 17.5 8.8 20.7 103.0 105.0 2 104.0 21.5 753 113 -51 2333
u/s lip - rectangular portion 1 0.0 2.5 2.5 1.3 28.2 101.0 103.0 2 102.0 21.5 108 16 -2 454
u/s lip - triangular portion 1 2.5 4.5 1.0 3.2 26.3 101.0 103.0 1 102.3 21.5 22 3 -1 85
d/s lip 1 16.5 17.5 1.0 17.0 12.4 101.5 103.0 1.5 102.3 21.5 32 5 -1 60
soil beneath slab - triangular 1 2.5 4.5 1.0 3.8 25.6 101.0 103.0 1 102.3 21.5 22 3 -1 74
soil beneath slab - rect. 1 4.5 16.5 12.0 10.5 18.9 101.0 103.0 2 102.0 21.5 516 70 -10 1318
soil beneath d/s lip 1 16.5 17.5 1.0 17.0 12.4 101.0 101.5 0.5 101.3 21.5 11 1 0 18
soil above u/s toe 1 0.0 1.5 1.5 0.8 28.7 105.0 107.0 2 106.0 32.5 98 13 -10 377
water weight above d/s part of sla 1 7.0 17.5 10.5 12.3 17.2 105.0 105.4 0.4 105.2 21.5 90 14 -9 233
Bridge abutment 591 -567 6654
footing 2 6.9 29.4 22.5 18.2 11.3 101.0 103.5 2.5 102.3 8 900 135 -25 1519
stem - rectangular portion 2 8.2 28.2 20.0 18.2 11.3 103.5 114.3 10.75 108.9 1.25 538 81 -95 907
stem - triangular portion 2 8.2 28.2 20.0 18.2 11.3 103.5 114.3 10.75 107.1 2.25 968 145 -132 1633
soil above sloped back of footing 2 8.2 28.2 20.0 18.2 11.3 103.5 116.0 12.5 109.8 2.25 1125 152 -199 1709
soil above footing heel 2 8.2 28.2 20.0 18.2 11.3 103.5 116.0 12.5 111.8 1 500 68 -110 759
conc. fill above footing toe 2 8.2 28.2 20.0 18.2 11.3 103.5 105.0 1.5 104.5 1.25 75 10 -5 114
water weight above footing toe 2 8.2 28.2 20.0 18.2 11.3 105.0 105.4 0.4 105.3 1.25 20 1 N/A 14
Bridge approach and retaining walls ### -1538 16276
u/s footing 1 6.9 14.9 8.0 10.9 18.5 101.0 103.5 2.5 102.3 31.5 630 95 -18 1748
u/s stem - rectangular portion 1 8.2 9.1 0.9 8.6 20.8 103.5 116.0 12.5 109.8 31.5 361 54 -71 1126
Copyright © 2016 Stephens Associates C 1 9.1 13.9 2.4 10.7 18.7 103.5 116.0 12.5 107.7 31.5 952 143 -143 2672
u/s soil above sloped back of wal 1 9.1 13.9 2.4 12.3 17.1 103.5 116.0 12.5 111.8 31.5 952 128 -209 2198
u/s soil above footing heel 1 13.9 14.9 1.0 14.4 15.0 103.5 116.0 12.5 109.8 31.5 394 53 -70 797
u/s soil above footing toe 1 6.9 8.2 1.3 7.5 21.9 103.5 114.0 10.5 108.8 25 328 44 -51 969
rect. soil between ret. walls 1 14.9 21.4 6.5 18.2 11.3 101.0 116.0 15 108.5 31.5 3071 415 -466 4664
d/s footing 1 21.4 29.4 8.0 25.4 4.0 101.0 103.5 2.5 102.3 31.5 630 95 -18 378
d/s stem - rectangular portion 1 27.3 28.2 0.9 27.7 1.7 103.5 116.0 12.5 109.8 31.5 361 54 -71 92
d/s stem - triangular portion 1 22.4 27.3 2.4 25.6 3.8 103.5 116.0 12.5 107.7 31.5 952 143 -143 539
d/s soil above sloped back of wal 1 22.4 27.3 2.4 24.0 5.4 103.5 116.0 12.5 111.8 31.5 952 128 -209 692
d/s soil above footing heel 1 21.4 22.4 1.0 21.9 7.5 103.5 116.0 12.5 109.8 31.5 394 53 -70 399
d/s soil above footing toe 1 28.2 29.4 1.3 28.8 0.6 103.5 110.0 6.5 106.8 31.5 256 35 -30 22
Bridge deck 142 -305 1601
slab 1 8.2 28.2 20.0 18.2 11.3 114.5 116.0 1.5 115.3 27.5 825 124 -265 1392
curb u/s 1 8.2 9.2 1.0 8.7 20.8 114.5 116.8 2.25 115.6 27.5 62 9 -20 193
curb d/s 1 27.17 28.17 1 27.67 1.75 114.5 116.8 2.25 115.6 27.5 62 9 -20 16
TOTALS 2546 kips -2666 k-ft 32914 k-ft
TOTALS, divided by tributary width 36 k/ft -38 k-ft/ft 470 k-ft/ft
661.2
Table of Uplift Forces (use uplift pressure estimated by creep theory, on separate sheet)
x (upstream-downstream direction) y (Uplift pressure, ksf) z (left-right) Area, Uplift M @ d/s toe of
Component Quant. CM-d/s sq. force, bridge abut.
u/s d/s avg width CM-u/s U/S D/S avg depth
toe feet kips due to uplift, k-
Spillway base slab, upstream of sheet piles ft
Rectangular portion 1 0.0 1.3 1.3 0.6 28.8 0.78 0.78 32.5 40.6 -32 -912
Triangular portion (not used, assume that uplift pressure at u/s side of sheet piles same as at u/s toe of slab)
Spillway base slab, downstream of sheet piles
Rectangular portion 1 1.3 17.5 16.3 9.4 20.0 0.27 0.27 32.5 528.1 -145 -2906
Triangular portion 1 1.3 17.5 16.3 6.7 22.8 0.21 0.00 32.5 528.1 -54 -1233
Bridge abutments, downstream of base slab
Rectangular portion 2 17.5 29.4 11.9 23.5 6.0 0.27 0.27 5 119.2 -33 -195
Bridge approaches and abutments, u/s of sheet piles
Rectangular portion 1 6.9 8.2 1.3 7.5 21.9 0.73 0.73 34.5 43.1 -31 -685
Triangular portion (not used, assume that uplift pressure at u/s side of sheet piles same as at u/s toe of slab)
Bridge approaches and abutments, d/s of sheet piles
Rectangular portion 1 8.2 29.4 21.3 18.8 10.6 0.27 0.27 34.5 733.1 -201 -2139
Triangular portion 1 8.2 29.4 21.3 15.3 14.2 0.21 0.00 34.5 733.1 -79 -1113
TOTALS -575 kips -9184 k-ft
TOTALS, divided by tributary width -8 k/ft -131 k-ft/ft
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.comtreet, Wilmington, MA 01887 (978) 988-2115Source page 85
Project: Number: 052-15-022 Sheet 9 of 13
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject: Spillway Stability
Checked By: JET Date: November 15, 2016 Hydrostatic Uplift Pressure Estimate
Estimate hydrostatic uplift pressures beneath spillway by Line of Creep method (FERC 2016 page 3-9)
Assume tension crack from top of soil to top of sheet piles.
Model seepage drop from top of sheet piles (point C) upstream, around sheet piles, to toe of slab downstream (po
Assume uplift pressure under bridge abutment footings downstream of slab based on tailwater elevation
A
Tension crack from A to C
B F
E
C Line of seepage (aka "creep")
D
Elevation of top of slab, ft = 105.0
Vert. dist. from top to bot. of slab u/s, ft. = 4.00
Horiz. dist. from slab bot. to sheet piles, ft. = 1.25
Horiz. dist. from sheet piles to slab d/s toe, ft. = 16.25
Elevation of bottom of slab u/s, ft = 101.0
Elevation of bottom of slab d/s (modeled), ft = 101.0
Sheet pile bottom elevation, ft. = 91.0
Distance from C to D, ft. = 10.0
Distance from D to F, ft. = 19.1
Unit weight of water, kcf = 0.062
Headwater El., ft HW = 113.5
Tailwater El., ft TW = 105.4
Total Creep distance, ft LT = 29.1
Pressure location A - u/s top B - u/s bot C - u/s top D - bot E - d/s top F - d/s bot
slab slab sheet piles sheet piles sheet piles slab
Creep dist. to pt. of interest, ft.LP = 0.0 0.0 0.0 10.0 17.3 29.1
Point El., ft HP = 105.0 101.0 101.0 91.0 101.0 101.0
Seepage = 8.1 8.1 8.1 5.3 3.3 0.0
potential
Position = 0.4 4.4 4.4 14.4 4.4 4.4
potential
Uplift pressure, ksf = 0.530 0.780 0.780 1.230 0.480 0.275
= γw * (Seepage + Position)
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.com 68 Main Street, Wilmington, MA 01887 (978) 988-2115Source page 86
Project: Number: 052-15-022 Sheet 10 of 13
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject: Spillway Stability
Checked By: JET Date: November 15, 2016 Hydrostatic Uplift Pressure Estimate
Estimate hydrostatic uplift pressures beneath bridge approaches by Line of Creep method
Assume linear uplift pressure beneath bridge approaches from upstream to downstream.
A
Tension crack from A to C
B
E F
C
Line of seepage (aka "creep")
D
Elevation of top of slab, ft = 105.0
Vert. dist. from top to bot. of slab u/s, ft. = 4.00
Horiz. dist. from slab bot. to sheet piles, ft. = 1.25
Horiz. dist. from sheet piles to slab d/s toe, ft. = 21.25
Elevation of bottom of slab u/s, ft = 101.0
Elevation of bottom of slab d/s (modeled), ft = 101.0
Sheet pile bottom elevation, ft. = 91.0
Distance from B to D, ft. = 10.1
Distance from D to F, ft. = 23.5
Unit weight of water, kcf = 0.062
Headwater El., ft HW = 113.5
Tailwater El., ft TW = 105.4
Total Creep distance, ft LT = 37.6
Pressure location A - u/s top B - u/s bot C - u/s top D - bot E - d/s top F - d/s bot
slab slab sheet piles sheet piles sheet piles slab
Creep dist. to pt. of interest, ft.LP = 0.0 4.0 4.0 14.1 21.6 37.6
Point El., ft HP = 105.0 101.0 101.0 91.0 101.0 101.0
Seepage = 8.1 7.2 7.2 5.1 3.4 0.0
potential
Position = 0.4 4.4 4.4 14.4 4.4 4.4
potential
Uplift pressure, ksf = 0.530 0.726 0.726 1.215 0.489 0.275
= γw * (Seepage + Position)
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.com 68 Main Street, Wilmington, MA 01887 (978) 988-2115Source page 87
Project: Number: 052-15-022 Sheet 11 of 13
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject: Spillway Stability
Checked By: JET Date: November 15, 2016 Case IIA: Unusual Loading Combination -- Ice
Estimate Ice Force
Case IIA: Unusual Loading Combination -- Ice
Regulations do not specify methodology for modeling ice loads on the dam.
FERC Chapter 3 recommends an ice pressure of 5 ksf be applied to the contact surface of the structure in contact
with the ice, based on the expected ice thickness, at the normal pool elevation. SA estimated ice thickness using
the modified Stefan equation as described in USACE EM 1110-2-1612 Ice Engineering and ERDC/CRREL
Technical Note 04-3, as shown below:
According to the equation, ice thickness is estimated as a function of accumulated freezing degree days (AFDD)
and a coefficient, C. AFDD is based on air temperature and is calculated starting with the first sustained freezing
period of each winter. SA estimated peak AFDD for each winter using daily temperature data measured at Blue Hill
Observatory, Canton, MA from 1893 to 2012. Because the observatory is at El. ~635 ft, about 500 ft. higher than
Old Shepard Street Dam and air temperature typically decreases with increasing elevation, we adjusted (increased)
the observatory-measured daily temperatures by the adiabatic temperature rate of change with elevation, which is
an increase of about 2.7 degrees F for an elevation drop of about 500 ft. AFDD for the 120 winters ranged from 33
to 886 degree-days F, with an average of 291 degree-days F and a value of 633 degree-days F at the 95th
percentile.
The C coefficient represents conditions at the dam that influence thickness of the ice sheet. Predicted ice thickness
varies proportionally with C. We estimated that the Pond and Dam may be between a "sheltered small river" and
"average lake with snow", for which C values above range from 0.21 to 0.7. SA selected a C value of 0.45 at the
middle of this range.
The ERDC/CRREL Technical Note 04-3 process for estimating ice thickness based on AFDD indicates that
"generally, the mean thickness and the thickness at the +/- 95% confidence limits are required for design purposes."
SA estimated the annual peak ice thicknesses using C =0.45 and ranked the thickness to estimate the mean and
95th percentile thickness.
Design AFDD at 95th Percentile 633 deg. days F
Design C coefficient: 0.45
Design Ice thickness at 95th Percentile 11 in.
Design Ice Pressure 5 ksf
Design Ice Load 4.7 k/ft
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.com 68 Main Street, Wilmington, MA 01887 (978) 988-2115Source page 88
Project: Number: 052-15-022 Sheet 12 of 13
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject: Spillway Stability
Checked By: JET Date: November 15, 2016 Case III: Extreme Loading Combination
Earthquake Water Forces
Case III: Extreme Loading Combination -- Normal Operating with Earthquake
b. Estimate earthquake water forces
Above ground surface, apply hydrodynamic forces from reaction of reservoir water on spillway using Westergaard
formula as presented in USACE EM 1110-2-2100 (2005). Below ground surface, use hydrostatic water loads from
load case I.
Change in water forces above ground surface from earthquake:
Upstream Downstream
PE = -0.231 k/ft -0.001
kh = -0.150 -0.150
γw = 0.062 kcf 0.062
(height of water above ground surface h = 6.5 ft 0.4
and below spillway crest)
The reference states that the line of action of the water force is
0.4h above ground surface = 2.6 ft 0.2
Elevation of ground surface = 107.0 ft 105.0
Elevation of hydrodynamic resultant = 109.6 ft 105.2
Elevation of toe of spillway = 101.0 ft 101.0
Moment arm about spillway toe = 8.6 ft 4.2
Moment (negative is driving, positive is resisting) = -2.0 k-ft 0.0
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.com 68 Main Street, Wilmington, MA 01887 (978) 988-2115Source page 89
Project: Number: 052-15-022 Sheet 13 of 13
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject: Spillway Stability
Checked By: JET Date: November 15, 2016 Earthquake Soil Forces
Case III: Extreme Loading Combination -- Normal Operating with Earthquake
c. Estimate earthquake soil forces
The Regulations do not specify a soil loading method for Case III.
Apply earthquake forces from soil backfill on on the upstream and downstream sides of the spillway using Wood's
method as described in ITL-92-11 (1992) and USACE EM 1110-2-2100 (2005). This method assumes the soil
backfill does not yield, and responds in an elastic manner. The change in soil forces from the earthquake
increases (i.e. adds to) the static driving forces and moments on the upstream side, and decreases the static
resisting forces and moments on the downstream side. On the downstream side, the force and moment reduction
are limited to the values of static soil force and moment (since seismic soil cannot apply tensile stress to spillway).
Change in horizontal soil force from earthquake:
Upstream Downstream Combined
Fsr = -0.2 k/ft -0.2 -0.4
γ = 0.038 kcf 0.073
h = 6.0 ft 4.0
kh = -0.150 -- -0.150
The reference states that the line of action of
the dynamic soil force is 0.63*h above base of = 3.8 ft 2.5
Elevation of toe of wall = 101.0 ft 101.0
Elevation of dynamic soil resultant = 104.8 ft 103.5
Moment arm about spillway toe = 3.8 ft 2.5
Moment (negative is driving, positive is resisting) = -0.8 k-ft -0.4 -1.2
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.com 68 Main Street, Wilmington, MA 01887 (978) 988-2115Source page 90
REPAIR DESIGN REPORT
OLD SHEPARD STREET DAM
CANTON, MASSACHUSETTS
STABILITY EVALUATION
EXISTING UPSTREAM SLOPE
SA No. 052-15-022Source page 91
Project: Number: 052-15-022 Sheet 1 of 6
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: November 15, 2016 Subject: Upstream Slope Stability
Checked By: JET Date: November 15, 2016
Purpose: Evaluate stability of Old Shepard Street Dam upstream slope.
Method and Model Cross-Section:
- Upstream slope consists of dumped rip-rap placed against an upstream stone masonry wall. SA modeled the geometry
to evaluate global stability since the riprap buttresses the upstream wall against sliding and overturning.
- Evaluate slope stability using Stabl6, with random search routine for critical failure surface (i.e. lowest Factor of Safety,
FS). SA found that Janbu "irregular" trial failure surfaces made up of line segments resulted in lower Factor of Safety than
circular trial failure surfaces.
- Geometry from topographic survey, results of borings, site observations and interviews with DPW personnel.
- Assume upstream stone masonry wall between embankment and upstream sediment/rip-rap. Assume upstream stone
masonry wall is mortared, based on SA seepage evaluation.
- We understand from discussion with DPW personnel that to buttress upstream wall, they dumped rip-rap into pond from
road, which settled into pond sediments. Assume that riprap and pond sediments formed a matrix of the two materials.
- Embankment phreatic surface from seepage analysis.
Material Properties:
Material Unit weight, pcf Cohesion, psf Friction angle, deg.
1. Impoundment sediment 100 0 27
2. Rip-rap 140 0 45
3. Stone masonry wall 150 100 45
4. Embankment fill, 0 to 6 ft. bgs 125 0 40
5. Embankment fill, 6 to 12 ft. bgs 125 0 30
6. Silty Sand and Gravel 140 0 45
Load Cases:
- Use slope stability load cases and Factors of Safety from Regulations section 10.14(9)(c).
- For each load case (except for earthquake), apply traffic surcharge load. Use traffic surcharge of 4.1 ft. of fill based on
interpolation of AASHTO LRFD Bridge Design Specifications (2012) Table 3.11.6.4-2 for 7-ft. high wall parallel to traffic,
with back face of wall within 1 ft. horizontally of traffic load.
- End of construction: Assume steady seepage at normal pool. Add traffic surcharge.
- Sudden drawdown from maximum pool: Assume impoundment dewatered to El. 107 ft. Embankment water levels based
on 100-year flood seepage analysis. Add traffic surcharge.
- Sudden drawdown from spillway crest/top of gates (i.e. top of stoplogs): Assume impoundment dewatered to El. 107 ft.
Embankment water levels based on normal pool seepage analysis. Add traffic surcharge.
- Steady seepage with maximum storage pool: Embankment water levels based on 100-year flood seepage analysis. Add
traffic surcharge.
- Earthquake: Embankment water levels based on normal pool seepage analysis. Use EQ acceleration = 0.15 g, per
Regulations. No traffic surcharge.
Results:
Embankment 1 Model
Load case Required FS
Phreatic Surface Estimated FS
End of construction, with traffic Normal Pool 1.3 1.9
Sudden drawdown from Maximum Pool, with traffic SDF > 1.1 1.7
Sudden drawdown from Spillway Crest/Top of Gates, with traffic Normal Pool 1.2 1.8
Steady seepage with maximum storage pool, with traffic SDF 1.5 1.9
Earthquake (no traffic surcharge) Normal Pool > 1.0 1.2
NOTES: 1. Required Factors of Safety (FS) are from Regulations section 10.14(9)(c), for upstream slope stability analysis.
Copyright © 2016 Stephens Associates Consulting Engineers LLC
Revisions:
By: Date:
By: Date:
SACE 00-1 (v. 1) 1/00 www.stephensengineers.com 668 Main Street, Wilmington, MA 01887 (978) 988-2115Source page 92
Project: Number: 052-15-022 Sheet: 2 of 6
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: 11/15/2016 Subject: Upstream Slope Stability
Checked By: JET Date: 11/15/2016
Stephens Associates
Consulting Engineers
Revisions:
Structural
By: Date: Insightful, Cost-
Saving Solutions for
Geotechnical
Buildings and
By: Date: Hydrology & Hydraulics
Infrastructure
60 Northrup Dr., Brentwood, NH 03833; Phone (603)772-1417; Fax (603)772-1418 668
www.stephensengineers.com Main Street, Ste. 250, Wilmington, MA 01887; Phone (978)988-2115; Fax (978)988-2117Source page 93
Project: Number: 052-15-022 Sheet: 3 of 6
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: 11/15/2016 Subject: Upstream Slope Stability
Checked By: JET Date: 11/15/2016
Stephens Associates
Consulting Engineers
Revisions:
Structural
By: Date: Insightful, Cost-
Saving Solutions for
Geotechnical
Buildings and
By: Date: Hydrology & Hydraulics
Infrastructure
60 Northrup Dr., Brentwood, NH 03833; Phone (603)772-1417; Fax (603)772-1418 668
www.stephensengineers.com Main Street, Ste. 250, Wilmington, MA 01887; Phone (978)988-2115; Fax (978)988-2117Source page 94
Project: Number: 052-15-022 Sheet: 4 of 6
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: 11/15/2016 Subject: Upstream Slope Stability
Checked By: JET Date: 11/15/2016
Stephens Associates
Consulting Engineers
Revisions:
Structural
By: Date: Insightful, Cost-
Saving Solutions for
Geotechnical
Buildings and
By: Date: Hydrology & Hydraulics
Infrastructure
60 Northrup Dr., Brentwood, NH 03833; Phone (603)772-1417; Fax (603)772-1418 668
www.stephensengineers.com Main Street, Ste. 250, Wilmington, MA 01887; Phone (978)988-2115; Fax (978)988-2117Source page 95
Project: Number: 052-15-022 Sheet: 5 of 6
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: 11/15/2016 Subject: Upstream Slope Stability
Checked By: JET Date: 11/15/2016
Stephens Associates
Consulting Engineers
Revisions:
Structural
By: Date: Insightful, Cost-
Saving Solutions for
Geotechnical
Buildings and
By: Date: Hydrology & Hydraulics
Infrastructure
60 Northrup Dr., Brentwood, NH 03833; Phone (603)772-1417; Fax (603)772-1418 668
www.stephensengineers.com Main Street, Ste. 250, Wilmington, MA 01887; Phone (978)988-2115; Fax (978)988-2117Source page 96
Project: Number: 052-15-022 Sheet: 6 of 6
Name: Old Shepard Street Dam, NID No. MA03104
Original Work: Canton, MA
By: NAO Date: 11/15/2016 Subject: Upstream Slope Stability
Checked By: JET Date: 11/15/2016
Stephens Associates
Consulting Engineers
Revisions:
Structural
By: Date: Insightful, Cost-
Saving Solutions for
Geotechnical
Buildings and
By: Date: Hydrology & Hydraulics
Infrastructure
60 Northrup Dr., Brentwood, NH 03833; Phone (603)772-1417; Fax (603)772-1418 668
www.stephensengineers.com Main Street, Ste. 250, Wilmington, MA 01887; Phone (978)988-2115; Fax (978)988-2117Source page 97
REPAIR DESIGN REPORT
OLD SHEPARD STREET DAM
CANTON, MASSACHUSETTS
STABILITY EVALUATION
EXISTING DOWNSTREAM STONE MASONRY RETAINING WALL
SA No. 052-15-022Source page 98
Old Shepard Street Dam, NID No. MA03104 Stephens Associates Consulting Engineers
Canton, MA SA Project No. 052-15-022
Stability Evaluation - Downstream Stone Masonry Retaining Wall
Representative Calculation By: N. Olson
Case II: Unusual Loading Combination - Flood Discharge, with Truck Load Date: 11/15/2016
Checked By: J. Turner
Date: 11/15/2016
Problem Geometry Defined:
Dist. (ft) 2 4 6 8 10 12 14 16 18 20 22
Purpose: Evaluate sliding and overturning stability of existing Old Shepard Street Dam downstream stone masonry retaining wall. Approx.
Approx.
Assumptions: Analysis of new retaining wall cast against existing stone block wall and on top of existing concrete slab. El. (ft)
- Assume
El. (ft.) wall extends
Dowels willfrom top El.and
be drilled 116. ft. to aninto
epoxied unknown bottom
stone block wallEl.tobelow downstream
use weight of stone(d/s) ground
block wall tosurface, however, critical model bottom El.
resist overturning
for wall stability
andissliding.
at d/s ground surfaceFS
The required (El.for109 ft., aka "base").
earthquake loading Use model
is >1.0 wall bottom
at normal El. 109 ft.for this case is surface
pool. Loading
- Actual
110 widthsurcharge
of wall is +unknown,
truck load however, SA probed
+ earthquake up topool.
at normal 3 ft. into
Truckvoids
loadbetween
modeledwall
asstones at various
two point loads onlocations
back of near
wall bottom of wall 110
Therefore, model wall as
and input as 4negative
ft. wide anchor
at base.loads.
Assume wall is 1 ft. wider at base than at top.
- Boring SA-1 (downstream side of road, ~15 ft. from west end of wall) encountered medium dense fill within the top 8 ft. below the embankment
crest (El. 116 ft.), and loose to very loose fill from about 8 to 12 ft. below embankment crest. Boring SA-2 (upstream side of road, ~40 ft. from
west end of wall), was similar, however, the change from medium dense to very loose fill was about 6 ft. below the embankment crest.
- Estimate average friction angle behind wall of 40 degrees, based on SPT-N
Existing correlation= with
wall thickness 3.5 friction angle for medium dense to dense upper fill.
Assume unit weight of 125 pcf.Assume new wall stem ft at top (assumed based on
- Assume sliding of wall along thickness
"internal" horizontal
= 3.0 ft at topjoints (i.e. sliding of stone
upstream masonry on stone masonry). Assume that wall repairs will, at
wall)
minimum, include mortaring of joints. Estimate sliding friction angle of 35 degrees between Creststone
El. ≈masonry,
107 ft. including at base of wall.
Bolivar Street
- Use active soil pressures upstream. No downstream (2,107)
soil pressure, since model wall does not extend below d/s ground surface.
- Based on seepage evaluation results, water level behind wall (upstream) and tailwater (downstream) (8.5,107) are each below wall bottom.
105 Criteria:
Stability 105
- Use Regulations section 10.14 (k) sliding Factors of Safety (FS) for significant hazard dam (Usual FS= 3, Unusual FS= 2, Extreme FS> 1)
- Regulations does not have requirements for overturning, but notes that that recommended safety factors also apply to "stress at the rock-
concrete interface and in the foundation."
- Judge that the soil at base of wall has an allowable bearing pressure of 3 ksf (i.e. ultimate bearing pressure of 6 ksf with FS = 2). For
comparison, the 1956 BridgeProposed Drawings indicate "Maximum Soil Pressure 4,780 psf"
Load Cases:
Concrete
Consider loading combinations from Regulations:
- Case I: Usual Loading Combination Wall- Normal Operating Condition - SA judged this condition to be not applicable, because SA 's seepage
evaluation shows the normal pool phreatic surface in the embankment to be below the wall base. In SA's judgment, therefore, wall failure during
Normal100Operating Condition is unlikely to cause dam breach. 100
- Case II: Unusual Loading Combination - Flood Discharge, with truck load.
o Water levels: Analyze for floods up to and including flood resulting from 100-year storm (water levels from SA seepage model, using water
Silty Sand and
levels from SA hydraulic model Existing
for Old Shepard Street Dam Emergency Existing Action Plan, 2012). Based on SA's seepage model, the 100-year flood
Stone Gravel Fill
model phreatic surface is El.109,Concrete equal to the bottom of the downstream wall. Therefore, assume no water pressures on back or base of the
wall. Block Wall
o Traffic surcharge load: Use traffic Wall surcharge of 4.1 ft. of fill based on interpolation of AASHTO LRFD Bridge Design Specifications (2012) Table
3.11.6.4-2 for 7-ft. high wall parallel to traffic, with back face of wall within 1 ft. horizontally of trafficAssumed Groundwater
load. Conservatively El. 97, vertical load
disregard
on wall back batter from truck load. Normal Pool
- Case IIA: Unusual Loading Combination - Ice (Not applicable)
- Case III: Extreme Loading Combination - Normal Operating
(0,96) (2,96) with Earthquake. Use EQ acceleration = 0.15 g, per Regulations. Apply active
95
earthquake force Assume
by Mononobe-Okabe
new wall toe =method. ~83 deg. (10,96) 95
Model Embankment thick (excerpt of SA Design Report figure, shown in reverse of diagram of spreadsheet variables) Refer to SA Design
1.0 ft.Section
Report for complete figure. (10,95) El. ≈ 95 ft.
(0,95)
Top of Concrete Slab - Assume new wall base
= 5 ft at bottom Existing wall thickness = 5 ft at GlacialDownstream
Till stone masonry wall
Assumed Ground
surface El. 95 ft. bottom (assumed based on
upstream wall)
90 90
Dist. (ft) 2 4 6 8 10 12 14 16 18 20 22
Page 1 of 6Source page 99
Old Shepard Street Dam, NID No. MA03104 Stephens Associates Consulting Engineers
Canton, MA SA Project No. 052-15-022
Stability Evaluation - Downstream Stone Masonry Retaining Wall
Spreadsheet Program Variables Defined:
Page 2 of 6Source page 100
Old Shepard Street Dam, NID No. MA03104 Stephens Associates Consulting Engineers
Canton, MA SA Project No. 052-15-022
Stability Evaluation - Downstream Stone Masonry Retaining Wall
Wall/Dam and Problem Geometry:
Location
Point El. Position Batter
Desig. Description (Y) (X) Length Vert.: Angle Factors
(feet) 1 Horiz. (deg.) Remarks
D Crest Front: 116.0 0.0
E Back: 116.0 3.0 0.0 0.0
B Base Front: Top 109.0 0.0
A Bottom 109.0 0.0
G Back: Top 109.0 4.0 4.0 Width of base
H Bottom 109.0 4.0 0.0 0.0 Batter of foundation surface
C Toe meets stem 109.0 0.0 0.0 0.0 0.0 Stem front batter
F Heel meets stem 109.0 4.0 0.0 7.0 8.1 Stem back batter
Water elevation at back 109.0
Water elevation at toe/face 109.0
Anchor Number 1 Force Loc. 0.0 0.0 0.0 Angle from horizontal, deg.
Anchor Number 1 Force Magnitude 0 Anchor force, kips
Anchor Number 2 Force Loc. 0.0 0.0 0.0 Angle from horizontal, deg.
Anchor Number 2 Force Magnitude 0 Anchor force, kips
Reduction factor for piezometric head at toe = 1.00 x head to account for losses
Reduction factor for piezometric head at heel = 1.00 x head to account for losses
Length of Tension Crack on Dam Base at heel = ft.
Unit weight of Wall = 150.00 pcf
Arching Effects of Wall as percent reduction of driving forces= 0.00 x 100 = % reduction
Earthquake Effects? no Yes or No
Earthquake effects calculated using Mass Bld. Code (MBC) or AASHTO AASHTO
Ice Force on Reservoir side of Wall (per foot of Wall) = 0.00 Kips 1 ft thick
Subsurface Profile:
Top Top Unit Wt. Wall Friction Rankine Earth Pressure
Layer Elevation Depth Phi Su (pcf) Srchrg. Factors Coefficient
Layer Number (feet) (feet) (degrees) (psf) Tot. Sat. (psf) Delta/Phi Su alpha Ka Ko Kp
Back of Wall/Dam:
Soil 1B 116.0 0.0 40 0 125 513 1 0.22 0.36 4.60
N/A 2B 109.0 7.0 40 0 125 513 0.22 0.36 4.60
At Wall Bottom 109.0 7.0 35 0 513 0.27 0.43 3.69
At Water Elevation 109.0 7.0 40 0 125 513 0.22 0.36 4.60
Front of Wall/Dam:
N/A 1F 109.0 0.0 40 0 125 0 0.22 0.36 4.60
N/A 2F 109.0 0.0 40 0 125 0 0.22 0.36 4.60
At Wall Bottom 109.0 0.0 35 0 0 1 0.27 0.43 3.69
At Water Elevation 109.0 0.0 40 0 125 0 0.22 0.36 4.60
Calculation: Calculate the wall stability based on assumption of monolithic structure
Assume: Calculation for stability per foot of wall.
Page 3 of 6Source page 101
Old Shepard Street Dam, NID No. MA03104 Stephens Associates Consulting Engineers
Canton, MA SA Project No. 052-15-022
Stability Evaluation - Downstream Stone Masonry Retaining Wall
Soil stresses and lateral earth pressures
Top Backfill Total Pore Effective Rankine Effective Horizontal Earth Pressures (psf)
Layer Elevation Thickness Stress Pressure Stress Active At-Rest Passive
Layer Number (feet) (feet) (psf) (psf) (psf) Top Bottom Top Bottom Top Bottom
Back of Wall/Dam:
Soil 1B 116 7 513 0 513 111 302 183 496 2357 6381
N/A 2B 109.0 0.0 1388 0 1388 302 302 496 496 6381 6381
At Wall Bottom 109.0 1388 0 1388 302 376 592 592 5120 5120
At Water Table El. 109.0 1388 0 1388 302 496 6381
Front of Wall/Dam:
N/A 1F 109 0 0 0 0 111 302 0 0 0 0
N/A 2F 109.0 0.0 0 0 0 0 0 0 0 0 0
At Wall Bottom 109.0 0 0 0 0 0 0 0 0 0
At Water Table El. 109.0 0 0 0 0 0 0
117 Wall Back 117 117 Wall Back 117
Wall Back
Wall Back - Active
116 513 Wall Front 116 0 116 513 Wall Front 116 111 183
Wall Front Wall Front - Passive
115 115 115 115 Wall Back - At rest
Wall Front - At Rest
114 114 114 114
Elevation (ft.)
Elevation (ft.)
Elevation (ft.)
Elevation (ft.)
113 113 113 113
112 112 112 112
111 111 111 111
110 110 110 110
1090 1388 1090 0 1090 1388 1090 0 302 496 592
108 108 108 108
0 500 1000 1500 0 1000 2000 0 1000 2000 0 100 200 300 400 500 600 700
Total Stress (psf) Porewater Pressure Effective Stress (psf)
Horizontal Effective Stress (psf)
(psf)
Select Lateral Earth Pressure NOTES FOR INPUT: To
Earth Pressure type: N= None In front of Dam select type of lateral earth pressure (LEP) used in
A= Active Behind Wall/Dam analysis, use A for active, 0 (zero) for at-rest, P for
passive, or N for none.
For passive resistance (Pp), active pressure should be
used on opposite side and Rp may be used to account
Reduction factor (Rp) for Passive Resistance (Pp): 0.33 for strain incompatibility with mobilization of active
NOTE: For full passive resistance reduction factor (Rp) = 1 stress.
Page 4 of 6Source page 102
Old Shepard Street Dam, NID No. MA03104 Stephens Associates Consulting Engineers
Canton, MA SA Project No. 052-15-022
Stability Evaluation - Downstream Stone Masonry Retaining Wall
Calculate Coefficient of Active Pressure for Earthquakes
Massachusetts Building Code uses pre-determined factor of 0.045. AASHTO calculates the coefficient using Mononobe-Okabe.
Method: AASHTO KAE = 0.26 (Calc. requires factors below for AASHTO method)
ΔKAE = 0.04
A (g) = 0.15 Site acceleration coefficient, per Regulations
β (deg.) = 0.0 Batter angle of wall back. Set to zero, since Rankine soil conditions used.
θ= 4.29 Wall or Dam: Dam Note: For MA Dam Regulations: If Wall, use kh = A/2. If Dam, use kh = A
ψ= 3.60
Forces on Wall Per Foot of Wall:
NOTE: LEP is lateral earth pressure Moment Moment
Force Arm Moment Force Arm Moment
Horizontal: Layer (kips) (feet) (kip-ft) Vertical: (kips) (feet) (kip-ft)
Back LEP above GWT L1:- Fill -0.666 2.3 -1.6 Wall Section W1=:+ 0.0 2.0 0.0
Back LEP. below GWT L2:- Fill 0.0 2.3 0.0 Wall Section W2=:+ 0.0 2.7 0.0
Back LEP below GWT L3:- Fill 0.0 3.5 0.0 Wall Section W3=:+ 0.0 0.0 0.0
Back LEP from Surcharge L4:- Fill -0.8 3.5 -2.7 Wall Section W4=:+ 0.0 2.0 0.0
Water on Back U1h:- Water 0.0 0.0 0.0 Wall Section W5=:+ 0.5 3.3 1.8
Water on Back U2h:- Water 0.0 0.0 0.0 Wall Section W6=:+ 3.2 1.5 4.7
Water on Base U3h:+ Water 0.0 0.0 0.0 Soil on Heel W7:+ 0.0 4.0 0.0
Water on Base U4h:+ Water 0.0 0.0 0.0 Soil on BackBatter W8:+ 0.4 3.7 1.6
Water on Base U4Ch:+ Water Soil on toe W9:+ 0.0 0.0 0.0
Water on Crest U5h:- Water 0.0 0.0 0.0 Water on Back U1v:+ 0.0 0.0 0.0
Water on Crest U6h:- Water 0.0 0.0 0.0 Water on Back U2v:+ 0.0 4.0 0.0
Water on Front U7h:+ Water 0.0 0.0 0.0 Water on Crest U5v:+ 0.0 0.0 0.0
Water on Heel U10:- Water 0.0 0.0 0.0 Water on Crest U6v:+ 0.0 0.0 0.0
Water on Heel U11:- Water 0.0 0.0 0.0 Water on Front U7v:+ 0.0 0.0 0.0
Water on Toe U12:+ Water 0.0 0.0 0.0 Water on Toe U8:+ 0.0 0.0 0.0
Water on Toe U13:+ Water 0.0 0.0 0.0 Water on Heel U9:+ 0.0 0.0 0.0
Front LEP above GWT L5:+ Soil 0.0 0.0 0.0
Front LEP below GWT L6:+ Soil 0.0 0.0 0.0 Hydrostatic Uplift U3v=:- 0.0 0.0 0.0
Front LEP below GWT L7:+ Soil 0.0 0.0 0.0 Hydrostatic Uplift U4v=:- 0.0 1.3 0.0
Ice Force on Wall Ice:- Ice 0.0 -0.5 0.0 Hydrostatic Uplift U4Cv=:- 0.0 0.0 0.0
Earthquake Ew:- Water Anchor 1 A1v:+ 0.0 0.0 0.0
Earthquake Es:- Active Soil 0.0 0.0 0.0 Anchor 2 A2v:+ 0.0 0.0 0.0
Earthquake Ei:- Inertia 0.0 0.0 0.0
Anchor 1 A1h:+ Anchor 0.0 -109.0 0.0
Anchor 2 A2h:+ Anchor 0.0 -109.0 0.0
Sum Horizontal Forces -1.4 Sum Vertical Forces 4.1
Sum Moments From Horizontal Forces -4.3 Sum Moments from Vertical Forces 8.1
Page 5 of 6Source page 103
Old Shepard Street Dam, NID No. MA03104 Stephens Associates Consulting Engineers
Canton, MA SA Project No. 052-15-022
Stability Evaluation - Downstream Stone Masonry Retaining Wall
CHECK DESIGN BASED ON BEARING SURFACE OF UNIT THICKNESS OF WALL:
SUM MOMENTS: 3.8 kip-ft (includes 0 % reduction due to arch 3-D effects)
Resist. Mom. (+) = W1+W2+W3+W4+W5+W6+W7+W8+U1v+U2v+U3h+U4h+U5v+U6v+U7+U8+U9+U12+U13+L5+L6+L7+A1+A2 = 8.1
Driv. Mom. (-) = L1+L2+L3+L4+U1h+U2h+U3v+U4v+U5h+U6h+U10+U11+Ew+Es+Ice = (includes reduction due to arch 3-D effects) -4.3
Check sum = 3.8
CHECK LOC. OF RESULTANT AS DISTANCE FROM LOCATION A:
Resultant Location RESULT
Foundation material : Soil LOWER CALC'D HIGHER
MIDDLE MIDDLE
1.3 0.9 2.7
Lower and higher middles based on 1/6 base length for soil, 1/4 base length for rock
Eccentricity (e): -1.1
CHECK SAFETY FACTOR AGAINST SLIDING ALONG BASE:
Sliding FS RESULT
Resisting Force: 2.88 FS=: 2.0
CHECK MAXIMUM BEARING PRESSURE (ksf): Bearing Pressure RESULT
TOE AVG. HEEL
2.7 1.0 -0.6
ANALYSIS:
ADD CONCRETE-ROCK BOND OF : 0 psi = 0.0 ksf
Sliding FS RESULT (with adhesion)
This section
Resisting not used for this project
Force: 2.9 FS=: 2.0
REQUIRED ROCK BOND: FOR FS = 2 0.0 ksf = 0.0 psi
TABLE: SLIDING AND BEARING PRESSURE RESULTS FOR ALL LOAD CASES
Bearing pressure (ksf)
Spillway Discharge Impoundment FS Sliding
Load Case Tailwater El. (ft.) Required Estimated
(cfs) Water El. (ft.)
Required Estimated (allowable) Toe Heel
Normal Not Applicable
Flood 610 116.5 108.4 4.3 1.7 0.4
2.0
Flood + Truck 610 116.5 108.4 2.0 < 3 ksf 2.7 -0.6
Earthquake 10 113.5 105.4 1.0 2.1 1.9 0.2
Page 6 of 6Source page 104
REPAIR DESIGN REPORT
OLD SHEPARD STREET DAM
CANTON, MASSACHUSETTS
APPENDIX C
OPERATION AND MAINTENANCE (O&M) MANUAL
SA No. 052-15-022 1/12/2018 Page C-1 of 12Source page 105
OPERATION AND MAINTENANCE (O&M) MANUAL
OLD SHEPARD STREET DAM, NID # MA03104
CANTON, MASSACHUSETTS
Summary
The purpose of this Operation and Maintenance (O&M) Manual (“Manual”) is to guide the Town in operating
and maintaining Old Shepard Street Dam, to address requirements of the Massachusetts Dam Safety Regulations
(302 CMR 10), and to support permit applications for Dam repairs and improvements. Key items are as follows:
• The Dam requires no routine operations during normal flows or floods.
• Operable water control structures at the Dam consist of 3-openings in the spillway controlled by stoplogs.
Maintain stoplogs in-place prior to and during floods. Removing stoplogs prior to or during floods increases
flow to Massapoag Brook, potentially increasing downstream flooding.
• The spillway also serves as a low-level outlet. Stoplogs can be removed from one or more openings of the
spillway to lower or dewater the impoundment for inspection, maintenance and/or repair.
• Rates of dewatering and refilling the impoundment are restricted by Regulations. Procedures and schedules
for dewatering and refilling are described below.
• Removing stoplogs from the spillway can be used to lower the impoundment in emergency during typical,
non-flood flows to attempt to mitigate dam breach. Operating the spillway during floods does not
significantly lower the impoundment, and stoplogs should therefore not be removed during floods or flood-
related emergencies. Refer to Old Shepard Street Dam Emergency Action Plan (EAP) for emergency
procedures.
• The Town should regularly monitor and maintain the Dam, and maintain records of operation, monitoring
and maintenance.
• A diversion channel is located at the southern end of the impoundment that diverts a portion of the inflow
from Massapoag Brook into Silk Mill Pond (the impoundment), with the remaining portion of flow
bypassing the pond and continuing west under Messinger Street to Beaver Meadow Brook and Bolivar Pond.
There is also an auxiliary outlet from the impoundment that discharges back to the diversion channel. These
components should be maintained to maintain the flow spilt and hydraulic performance of the system.
These items are discussed in more detail on the following pages, and should be thoroughly and completely read
and understood as part of training.
.
Fair Weather and Dewatering Operation
The operational components of Old Shepard Street Dam consist of concrete spillway with three openings
controlled by stoplogs. Fair-weather operations include the following:
• Maintain stoplogs at ±El. 113.25 ft. (about 3.5 ft. below the top of spillway concrete). Impoundment
elevation is indicated by a staff gage located on the right (looking downstream) side of the spillway.
• The spillway can be operated (stoplogs removed) to lower the impoundment water level (dewater) during
typical, non-flood inflow for inspection, maintenance, and/or repair of the Dam.
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• For non-emergency dewatering:
o Remove stoplogs incrementally from one of the three stoplog bays.
o Remove the top stoplog at the start of dewatering and record the impoundment elevation at the spillway
staff gage. Once the impoundment level has lowered by the height of one stoplog (9 in., or 0.75 ft.),
remove an additional stoplog. Repeat until the desired water elevation is reached.
o Stoplogs can be removed manually using the stoplog pullers or chains. Alternatively, a backhoe or other
lifting equipment may be used.
o Monitor dam during dewatering as described below.
• To refill impoundment:
o Replace all stoplogs in 2 of the 3 openings of the spillway (if stoplogs were removed). Replace stoplogs
in the 3rd opening incrementally, as described below.
o To maintain downstream flow during refilling, replace one stoplog once the depth of flow over the
previous stoplog is 1.0 ft. or greater.
o If inflow is too low for 1.0 ft. of flow over stoplogs, partially insert a stoplog, leaving a gap of 3 in.
above the previous stoplog such that water flows through the 3-in. gap between stoplogs. Once the pond
level rises to the top of the top stoplog, seat the top of stoplog to close the gap such that water no longer
discharges between stoplogs.
o Repeat the steps above until the pond level is above El. 113.25, at which point remaining stoplogs can
be replaced.
o Generally, inflow to the pond of about 3 cfs (roughly equal to 3 in. of flow above stoplogs in one bay)
is needed to refill the impoundment.
Flood Operation
The Dam requires no routine operations during floods. Maintain stoplogs at elevation cited above. Removing
stoplogs during or prior to floods increases flow to Massapoag Brook, increasing downstream flooding. Monitor
Dam and diversion channel as described below.
Emergency Operation
Refer to Old Shepard Street Dam Emergency Action Plan (EAP) for emergency procedures. The EAP
recommends the following operations during an Emergency:
• If failure of the dam is imminent or has occurred (Condition Red in the EAP), do not remove stoplogs;
• During a fair-weather Emergency where a hazardous situation at the Dam is developing that could cause
Dam failure (Condition Yellow in the EAP), dewatering the impoundment by removing stoplogs may
mitigate dam breach if the impoundment can be lowered sufficiently before the breach develops. Refer to
EAP for additional information. If removing stoplogs to mitigate dam breach, remove all logs without delay
between logs described above. We estimate that, during fair weather, the impoundment would be
substantially drained (inflow about equal to outflow with stoplogs removed) about 1 hour after commencing
stoplog removal.
• During a flood-related (high inflow) emergency, removing stoplogs does not significantly lower the
impoundment but may exacerbate downstream flooding. Do not remove stoplogs in advance of or during
flooding.
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Old Shepard Street Dam, Canton, MA
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Monitoring Procedures
When to Monitor:
A professional engineer experienced in dam engineering retained by the Town, the Town Engineer or other
DPW personnel trained and experienced in dam monitoring should monitor the dam regularly as follows:
• Every three months during fair weather;
• During wet weather:
o Once daily while predicted or actual precipitation exceeds 4 in. in 24 hours according to the National
Weather Service local forecast1 or the Town’s retained weather forecasting service;
o Once daily when a Flood Watch is issued by the National Weather Service;
o Once every 4 hours while predicted or actual precipitation exceeds 5 in. in 24 hours;
o Once every 4 hours while Flood Warning is issued by the National Weather Service;
o Hourly if the impoundment overtops the embankment but the overtopping does not cause progressive
erosion;
o Continuous observation if an Emergency is identified (e.g. progressive erosion - refer to Emergency
Action Plan).
o If Town personnel note any of the deficiencies listed below under “What to Monitor”, monitor Dam
continuously until flooding recedes or otherwise instructed by Town’s dam engineer; and
• Once immediately after each storm where precipitation exceeds 4 in. over 48 hours;
• Once immediately if earthquake-related ground shaking is felt by Town personnel or reported by residents;
• During dewatering (emergency or non-emergency), hourly by the Town Engineer (a Registered Professional
Engineer) for the first four hours after the start of drawdown. Thereafter, once every 24 hours by the Town
Engineer or trained Town DPW personnel until drawdown is completed.
• As a Significant Hazard dam, a visual inspection (Phase I) should be made every five years by a Professional
Engineer registered in the Commonwealth of Massachusetts experienced in dam engineering, per
Regulations 302 CMR 10.10 (2).
What to Monitor:
A professional engineer engaged by the Town, or Town personnel trained and experienced in dam monitoring
should monitor the Dam as follows:
• Observe embankment upstream slope (in impoundment where visible), crest, downstream slope and stone
masonry walls, toe, spillway, stoplogs, downstream area, and inlet and outlet of bridge/culvert beneath Old
Shepard. Observe diversion channel, including inlet to Silk Mill Pond and Messinger Street culvert.
• Observe water elevations at downstream culverts and properties for potential flooding when operating the
Dam;
• Record observations on the attached Owner’s Abbreviated Monitoring Checklist. The purpose of the
checklist is to guide the Town in routine monitoring of the Dam and for the convenience of the Town’s dam
engineer in responding to Emergency. An original of the checklist should be kept by the Town such that
photocopies can be used and hand-annotated as needed.
• Photograph the Dam, the staff gage at the spillway, Messinger Street culvert, and the diversion channel.
Photographs should show both large portions of the Dam as well as close-up view of specific features/issues
and include date and time stamps;
1
www.weather.gov/nerfc/forecastprecipitation
Operation and Maintenance Manual
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• Check for the following deficiencies:
o Signs of erosion on upstream slope, crest, downstream slope, and toe of embankment wall, particularly
if floodwater is overtopping crest;
o Overgrown vegetation;
o Debris blocking spillway, Old Shepard Street bridge, diversion channel, inlet to Silk Mill Pond, or
Messinger Street culvert. Remove blockages;
o Concrete deterioration and/or damage, e.g. surface erosion, spalling, significant new cracking, opening
of joints, etc.
o If any of the following deficiencies is observed, contact MADEP DCR ODS and a Professional
Engineer experienced in dam engineering for further evaluation immediately.
Uncontrolled seepage at embankment, stone masonry retaining wall of embankment downstream
face, and/or near downstream side of the retaining wall. Turbid (muddy or cloudy) seepage indicates
greater concern than clear seepage.
Boils in vicinity of toe or downstream;
Sinkholes and whirlpools on the upstream face;
Progressive erosion of soil or rip-rap, undermining of asphalt, dislodged stone masonry, etc. if
floodwater is overtopping the embankment;
Signs of obvious settlement, movement, depressions, holes, or cracking of upstream slope, crest
(road surface), toe or downstream of embankment, spillway, or bridge;
Document observations using photocopies of the Owner’s Abbreviated Monitoring Checklist (Attached).
Compare monitoring results with previous monitoring, inspections, and photos and implement maintenance,
repair and/or emergency notifications, as required. If deficiencies appear to be worsening, consult Registered
Professional Engineer and keep MADEP DCR ODS appraised.
Emergency Action:
If any of the above deficiencies are observed during flooding, evaluate severity and classify Emergency in
accordance with the Old Shepard Street Dam Emergency Action Plan, and enact the notification procedures in
that EAP.
Maintenance
Address deficiencies identified by monitoring described above, and perform routine maintenance as follows:
Seasonal Maintenance:
Perform the following routine seasonal maintenance in conjunction with seasonal monitoring. In non-
emergencies, perform vegetation control before monitoring and other maintenance for improved visibility of
dam features.
• Mow/cut vegetation; remove trees/brush on and within 25 ft. of embankment, and structures (e.g. spillway,
low-level outlet, bridge, concrete and stone masonry retaining walls, downstream rip-rap, etc.);
• Fill holes (e.g. animal burrows, etc.); remove animals creating holes as needed;
• Remove debris and flow obstructions at the spillway, Old Shepard Street bridge, inlet to Silk Mill Pond
from the diversion channel, auxiliary outlet from the Pond back to the diversion channel, and Messinger
Street culvert.
• Replace, repair or secure missing, leaking, deteriorated or unsecured stoplogs and stoplog pullers.
Operation and Maintenance Manual
Old Shepard Street Dam, Canton, MA
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Annual Maintenance:
In addition to seasonal maintenance, perform the following annually:
• Replace missing riprap and/or sand and gravel bedding;
• Perform road repairs as needed (e.g. pothole repair, crack filling, etc.);
• Smooth surficial erosion of grassy areas and reseed with hardy grass. If significant erosion (e.g. on slopes,
at downstream toe, etc.) is noted, consult Town’s Dam Engineer for repair procedure;
• Prepare surface and repaint peeling and rusting metal components as needed (e.g. bar grating, railing,
fences etc.). Repair or replace deteriorated and corroded components as needed;
• Repair voids and repoint mortar of stone masonry as needed;
• Test and update the Emergency Action Plan as detailed in the EAP.
References
References Specific to Old Shepard Street Dam:
Stephens Associates Consulting Engineers, LLC (SA) (2012), “Old Shepard Street Dam, aka Shepard Street
Dam, Phase I Inspection/Evaluation Report,” September 14, 2012. (2012 Old Shepard Street Dam Phase I
Report).
Stephens Associates Consulting Engineers, LLC (2012) “Emergency Action Plan, Old Shepard Street Dam,
Canton, Massachusetts.”
Stephens Associates Consulting Engineers, LLC (SA) (2007), “Old Shepard Street Dam, aka Shepard Street
Dam, Phase I Inspection/Evaluation Report,” July 30, 2007. (2007 Old Shepard Street Dam Phase I Report).
Other References:
Massachusetts Department of Conservation and Recreation, Office of Dam Safety (2010b) “Policy on Trees on
Dams,” http://www.mass.gov/dcr/pe/damSafety/DamSafety-PolicyonTrees.htm, accessed by SA on February
24, 2010.
MA DCR ODS (2017), “302 CMR 10.00 Dam Safety,” Commonwealth of Massachusetts Department of
Conservation and Recreation, Office of Dam Safety, February 10, 2017 (Regulations).
Federal Emergency Management Agency (FEMA) (2005). “Impacts of Animals on Earthen Dams,” FEMA 473,
September, 122 pp.
Federal Emergency Management Agency (FEMA) (2005). “Impacts of Plants on Earthen Dams,” FEMA 534,
September, 115 pp.
Federal Emergency Management Agency (FEMA) (2005). “Dam Owner’s Guide to Plant Impact Plants on
Earthen Dams,” FEMA L-263, September, 16 pp.
Federal Emergency Management Agency (FEMA) (1987). “Dam Safety: An Owner’s Guidance Manual,”
FEMA 145, July, 117 pp.
Attachments
• Owner’s Abbreviated Monitoring Checklist
Operation and Maintenance Manual
Old Shepard Street Dam, Canton, MA
052-15-022 1/12/2018 Page 5 of 5Source page 110
OWNER'S ABBREVIATED MONITORING CHECKLIST
NAME OF DAM: Old Shepard Street Dam, Canton, MA STATE ID #: 6-11-50-2
MONITORING DATE: NID ID #: MA03104
TABLE OF CONTENTS SUMMARY
DAM FEATURE SHEET MONITORING DATE:
TABLE OF CONTENTS/SUMMARY 1 MONITORED BY:
Near bridge: concrete gravity walls; right of bridge: stone masonry wall
EMBANKMENT CREST 2 TEMP/WEATHER:
EMBANKMENT UPSTREAM SLOPE 3 SPILLWAY
STAFF GAGE EL.:
EMBANKMENT DOWNSTREAM WALLS 4
MAINTENANCE PERFORMED/DATE:
EMBANKMENT DOWNSTREAM SLOPE 5
PRIMARY SPILLWAY 6
Template date: 1/12/2018 Page 1 of 6Source page 111
OWNER'S ABBREVIATED MONITORING CHECKLIST
NAME OF DAM: Old Shepard Street Dam, Canton, MA STATE ID #: 6-11-50-2
MONITORING DATE: NID ID #: MA03104
EMBANKMENT (CREST)
MONITOR
ACTION
REPAIR
NO
AREA CONDITION OBSERVATIONS
SURFACE TYPE Near bridge: concrete gravity walls; right of bridge: stone masonry wall
SURFACE CRACKING
SINKHOLES, EROSION
CREST VERTICAL ALIGNMENT (DEPRESSIONS)
HORIZONTAL ALIGNMENT
RUTS AND/OR PUDDLES
VEGETATION (PRESENCE/CONDITION)
PIPE DRAINS (outlet at DS fence post
footing and stone masonry wall)
CONTACT (e.g. with concrete walls, fence
post footing, etc.
FENCE
ADDITIONAL COMMENTS:
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OWNER'S ABBREVIATED MONITORING CHECKLIST
NAME OF DAM: Old Shepard Street Dam, Canton, MA STATE ID #: 6-11-50-2
MONITORING DATE: NID ID #: MA03104
EMBANKMENT (UPSTREAM SLOPE)
MONITOR
ACTION
REPAIR
NO
AREA CONDITION OBSERVATIONS
SLIDE, SLOUGH, SCARP Near bridge: concrete gravity walls; right of bridge: stone masonry wall
RIP-RAP SLOPE PROTECTION
SINKHOLE/ANIMAL BURROWS
U/S CONTACT WITH CONCRETE WALLS
SLOPE EROSION
UNUSUAL MOVEMENT
VEGETATION (PRESENCE/CONDITION)
ADDITIONAL COMMENTS:
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OWNER'S ABBREVIATED MONITORING CHECKLIST
NAME OF DAM: Old Shepard Street Dam, Canton, MA STATE ID #: 6-11-50-2
MONITORING DATE: NID ID #: MA03104
EMBANKMENT DOWNSTREAM WALLS
MONITOR
ACTION
REPAIR
NO
AREA CONDITION OBSERVATIONS
WALL TYPE Near bridge: concrete gravity walls; right of bridge: stone masonry wall
WALL ALIGNMENT
WALL CONDITION
D/S WALLS SEEPAGE OR LEAKAGE
CONTACT/INTERSECTION WITH
ADJACENT WALLS
EROSION/SINKHOLES BEHIND WALL
ANIMAL BURROWS
UNUSUAL MOVEMENT
WET AREAS AT TOE OF WALL
CONDITIONS OF JOINTS
DOWNSTREAM REVETMENT
VEGETATION
PIPE DRAINS
ADDITIONAL COMMENTS:
Template date: 1/12/2018 Page 4 of 6Source page 114
OWNER'S ABBREVIATED MONITORING CHECKLIST
NAME OF DAM: Old Shepard Street Dam, Canton, MA STATE ID #: 6-11-50-2
MONITORING DATE: NID ID #: MA03104
EMBANKMENT (DOWNSTREAM SLOPE)
AREA
MONITOR
ACTION
REPAIR
NO
INSPECTED CONDITION OBSERVATIONS
WET AREAS (NO FLOW) Near bridge: concrete gravity walls; right of bridge: stone masonry wall
SEEPAGE
SLIDE, SLOUGH, SCARP
D/S RIP-RAP SLOPE PROTECTION
SLOPE SINKHOLE/ANIMAL BURROWS
EROSION
UNUSUAL MOVEMENT
VEGETATION (PRESENCE/CONDITION)
ADDITIONAL COMMENTS:
Template date: 1/12/2018 Page 5 of 6Source page 115
OWNER'S ABBREVIATED MONITORING CHECKLIST
NAME OF DAM: Old Shepard Street Dam, Canton, MA STATE ID #: 6-11-50-2
MONITORING DATE: NID ID #: MA03104
PRIMARY SPILLWAY
MONITOR
ACTION
REPAIR
NO
AREA CONDITION OBSERVATIONS
SPILLWAY TYPE Near bridge: concrete gravity walls; right of bridge: stone masonry wall
SPILLWAY CONDITION
UNUSUAL MOVEMENT
SPILLWAY D/S TRAINING WALLS (bridge abutments)
U/S WINGWALLS (concrete retaining walls)
APPROACH AREA
DISCHARGE AREA
STOPLOGS
RAILING AND BAR GRATING
DEBRIS
ADDITIONAL COMMENTS:
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REPAIR DESIGN REPORT
OLD SHEPARD STREET DAM
CANTON, MASSACHUSETTS
APPENDIX D
DESIGN DRAWINGS AND TECHNICAL SPECIFICATIONS
(SUBMITTED SEPARATELY, ATTACHED BY REFERENCE)
SA No. 052-15-022 1/12/2018 Page D-1 of 1