hydrology and hydraulics summary - sterlinghighway.net · hydrology and hydraulics summary prepared...

Hydrology and Hydraulics Summary

Prepared for:

State of Alaska

Department of Transportation and

Public Facilities

Prepared by:

HDR Alaska, Inc.

2525 C Street, Suite 305

Anchorage, Alaska 99503

March 2006


Sterling Highway MP 45 to 60 Project

i

TABLE OF CONTENTS

1.0 Introduction...................................................................................................................................... 1

2.0 Study Purpose .................................................................................................................................. 1

3.0 Field Methods .................................................................................................................................. 2

4.0 Field Survey Methods...................................................................................................................... 2

5.0 Report Figures.................................................................................................................................. 2

6.0 Hydrology ........................................................................................................................................ 3

6.1 Design Flood Flows ............................................................................................................ 3

6.2 Drainage Basin.................................................................................................................... 4

7.0 Hydraulics...................................................................................................................................... 11

7.1 Drainages with Delineated Basins .................................................................................... 11

7.2 Drainages with Undelineated Basins ................................................................................ 12

8.0 Fish Passage Considerations .......................................................................................................... 13

8.1 Drainage Site D13 (Cooper Creek Alternative)................................................................ 14

8.2 Drainage Site D25 (Cooper Creek Alternative)................................................................ 15

8.3 Drainage Site D50 (G South Alternative) and D78 (Juneau Creek Alternative),

Tributary to Bean Creek ................................................................................................... 16

8.4 Drainage Site D56 (G South Alternative)......................................................................... 17

8.5 Drainage Sites D52 and D53 (G South Alternative), Main Stem of Bean Creek ............. 18

8.6 Drainage Site D58 (Cooper Creek - G South alternatives)............................................... 19

8.7 Drainage Site D66 (Cooper Creek - G South alternatives)............................................... 20

8.8 Drainage Site D67 (Cooper Creek - G South Alternatives).............................................. 21

8.9 Drainage Site D94 (Juneau Creek Alternative)................................................................. 22

8.10 Drainage Site D95 (Juneau Creek Alternative)................................................................. 23

8.11 Drainage Site D104 (All Alternatives); Fuller Creek ....................................................... 24

9.0 References...................................................................................................................................... 26



ii

List of Tables Table 1: Drainage Properties ........................................................................................................................ 5

Table 2: Culvert Flood Flow Capacities ..................................................................................................... 12

List of Figures

Figure 1: Index Map .............................................................................................................................. 1

Figure 2: Drainage Basins ..................................................................................................................... 2

Figure 3: Detailed Map of Project Area ................................................................................................ 2









Figure 12: Drainage site D13, downstream side of Snug Harbor Road crossing. ................................. 12

Figure 13: Drainage site D13, upstream side of Snug Harbor Road crossing. ...................................... 12

Figure 14: Drainage site D25, downstream side of existing road crossing. .......................................... 15

Figure 15: Drainage site D25, upstream side of existing road crossing. ............................................... 15

Figure 16: Drainage site D50................................................................................................................. 14



Figure 19: Drainage sites D52 and D53. ............................................................................................... 18

Figure 20: Drainage site D58 upstream side of existing road crossing. ................................................ 19

Figure 21: Drainage site D58 downstream side of existing road crossing. ........................................... 19







Figure 28: Drainage site D104, upstream reach showing gravel deposition. ........................................ 24

Figure 29: Drainage site D104, downstream side of existing road crossing. ........................................ 25

Figure 30: Drainage site D104, upstream side of existing road crossing. ............................................. 25



1

1.0 INTRODUCTION

The Alaska Department of Transportation and Public Facilities (DOT&PF) is evaluating

alternatives to improve the Sterling Highway in the Cooper Landing area. The proposed project

is located approximately between Mileposts (MP) 45 and 60 on the Sterling Highway along the

Kenai River. DOT&PF contracted HDR Alaska, Inc. (HDR) to provide engineering and

environmental support for preparation of a Supplemental Environmental Impact Statement

(SEIS).

Kenai River Valley

The three build alternatives under consideration in the SEIS include the Cooper Creek, G South,

and Juneau Creek Alternatives, shown on Figure 1. The three build alternatives share the same

alignment at both the eastern and western ends of the project. For the purposes of this

Hydrology and Hydraulics Summary, these shared areas are referred to as the “all alternatives”

area. The Cooper Creek and G South alternatives share a corridor for part of their length along

with the Juneau Creek and G South alternatives. Drainages along these shared alignments are

grouped together under these titles in Table 1.

2.0 STUDY PURPOSE

This report summarizes the findings of the investigation carried out on all of the identified small

streams and drainages intersecting the three build alternative alignments being considered in the

SEIS. Investigation of the three larger streams: Kenai River, Cooper Creek, and Juneau Creek

were not included in this scope of work. This is a guidance document and the conveyance sizing

recommendations should not be construed as final design numbers. Further investigation and

analysis of flood flows, conveyance design, and fish passage considerations will be carried out

during the design phase. The primary objectives of the study were:

Take field measurements at locations where drainage conveyances will be needed across the

alignments.

Provide preliminary guidance on conveyance structures sizing based on projected flood flows,

fish passage requirements, and DOT&PF design criteria.



2

The fieldwork was conducted on May 4, 5, 6, 11, and 12, 2005. Supplemental field work was

completed on October 14, 2005 based on new aerial photography and questions generated as a

result of preliminary data analysis. The work was completed by HDR staff.

3.0 FIELD METHODS

Alignment areas inaccessible by vehicle were traversed on foot. All observed drainages with

flowing water and seeps were surveyed. A total of 47 drainages and 13 seeps were surveyed.

Seeps were defined as areas where there was wet ground with an obvious drainage direction but

no continuous overland flow channel. Often the water could be seen running through holes in

the vegetation cover and between roots and/or forming boggy areas. Areas where this ground

water discharge required a drainage conveyance were logged as seeps.

Areas where the proposed alignments are adjacent to the existing highway were surveyed by car.

47 existing culverts where located and surveyed. 22 culverts are associated with definable

drainage basins. Many of these contained active streams but some were dry at the time of the

survey. Kenai River, Cooper Creek, and Juneau Creek will require substantial bridge structures

and were not surveyed.

4.0 FIELD SURVEY METHODS

At each drainage site the following information was collected:

• Coordinates and elevation from handheld GPS receiver

• Width and depth of flow at the time of survey

• Width and depth at the ordinary high water mark (OHW)

• Channel slope

• Direction of flow

• Stream bottom material

• Photos

• Description and other notes on the drainage

5.0 REPORT FIGURES

All identified drainages, seeps and existing culverts are shown on Figures 1 through 11. Figure 1

shows the alignment alternatives and an index map for Figures 3 through 11. Figure 2 shows the

full extent of all delineated drainage basins along the alignments. Basins are identified by

drainage number. Figures 3 through 11 show the alternative alignments in detail with the

individual drainage crossing sites. The following information is depicted on these figures:

• Alternative alignment centerlines and limits of cut and fill.

• All drainages, seeps and existing culverts as field surveyed. Locations shown are from

field-collected GPS waypoints and may not correspond exactly to the centerline of the

alignments. The ID numbering is random, starting on the east end of the project area and



3

following the most southern alternative until it intersects with the next northern

alternative.

• Drainage basin boundaries are shown where applicable. The full extent of some basins

can only be seen on Figure 2. Basins for the different alternatives overlap where one

alternative is downslope from another. In these cases the identifier for the downslope

alternative is shown on the additional downslope area and the identifier for the upslope

alternative is shown on the more upslope basin area.

• Approximate location of stream and drainage channels. Drainage channel mapping is an

approximation taken from USGS mapping, field locates, 5-foot contour mapping, and

aerial photo interpretation. The full extent of each drainage was not field checked.

• Fish symbols are used to indicate fish bearing streams. Fish streams were identified from

previous fisheries work done as part of this project and from information contained in the

Alaska Department of Fish and Game (ADF&G) and Alaska Department of Natural

Resources Atlas and Catalog of Waters Important for the Spawning, Rearing or

Migration of Anadromous Fishes. The fisheries investigation conducted by HDR

personnel is summarized in the November 2004 report titled “Fisheries Evaluation,

Sterling Highway Milepost 45 to 60” and in the January 2006 “2005 Addendum to the

2004 Fisheries Evaluation.” Two additional fish streams were identified by the H&H

crews during the supplemental October field work.

• Landmarks such as roads.

6.0 HYDROLOGY

6.1 Design Flood Flows

Flood flows from definable drainage basins are based on regression equations and methodology

contained in "Estimating the Magnitude and Frequency of Peak Streamflows for Ungaged Sites

on Streams in Alaska and Conterminous Basins of Canada" (U.S. Geological Survey [USGS]

Water Resources Investigations Report 03-4188). To calculate flood flows (Q) for the 2, 50,

100, and 500-year return intervals, 45 inches of annual precipitation (from USGS Jones and Fahl

mapping) was incorporated into the Area 4 regression equations. Basin storage surface area

values, represented by ponds and lakes, were ignored if less than 0.5%.

All but six of the drainage basins are below the size limit for application of the regression

equations method. Therefore, the minimum size (1.07 square miles) restriction for application of

the regression equations was ignored. Regression analysis was used in the absence of viable

alternative methods.

The flood flows determined by regression analysis were compared with flows calculated using

the rational method (using a runoff coefficient for undeveloped land [0.2]), on a few select

drainages. This limited comparison indicates the regression numbers are the more conservative

values. No specific runoff coefficients are available for the mixed forested uplands that

dominate many of these drainages, and the regression method was chosen as the more

conservative approach in spite of the small size of the drainages. An alternate method of flood

flows calculation may be chosen during final design.



4

6.2 Drainage Basin

Drainage basin boundaries were defined using 5-foot contour base mapping generated for the

project, supplemented with USGS quadrangle maps and aerial photo overlays. Some basins

were considered too small or the topography too vague for delineation. These drainages are

designated as “undelineated” in Table 1 and the discussion.

Table 1 lists drainage sites noted through field reconnaissance and through aerial photo

interpretation, including basin characteristics, flood flows, and proposed minimum culvert sizes.

Fisheries streams are also indicated. Length of the conveyance was measured off the projected

cut and fill limits as shown on the Figures 3 through 11.

Hydro

logy a

nd H

ydra

uli

cs

Sum

mary

Ste

rlin

g H

ighw

ay M

P 4

5 t

o 6

0 P

roje

ct

5

Tab

le 1

: D

rain

age

Pro

per

ties

for

Each

Bu

ild

Alt

ern

ati

ve

ID

Fish Stream

OHW Width (ft)

OHW Depth (ft)

Slope (%)

Basin Area (sq

miles)

Q2 (cfs)

Q50 (cfs)

Q100 (cfs)

Q500 (cfs)

Existing Culvert

Size (in)

Proposed Culvert

length (ft)

Proposed Culvert

Size (in)

Q100 F

lood

ev

alu

ati

on

for

culv

erts

wit

h e

qu

ivale

nt

size

gre

ate

r th

an

48

”

Fie

ld N

ote

s

Coo

per

Cre

ek

Alt

ern

ati

ve

D1

-D9

(se

e A

ll a

lter

nat

ives

)

D1

0

5

.0

2.0

1

0%

0

.77

1

9

79

9

5

13

7

60

1

40

4

8

Pro

po

sed

cu

lver

t w

ill

pas

s

Q100 f

low

at

HW

/D =

1.5

Hig

h w

ater

mar

k a

t cu

lver

t's

per

ch

ed o

utl

et a

t 2

ft.

Cu

lver

t ap

pea

rs o

ver

size

d p

erh

aps

for

icin

g

con

sid

erat

ion

s.

D1

1

3

.0

1.0

3

%

0.2

3

6

28

3

4

51

3

6

12

5

36

S

mal

l st

ream

; w

ater

fall

on

no

rth (

up

stre

am)

sid

e o

f

road

. C

han

nel

dim

ensi

on

s ar

e o

f so

uth

(do

wn

stre

am

)

sid

e.

D1

2

3

.0

1.0

1

%

0.7

8

19

8

0

96

1

39

24

1

25

4

8

Pro

po

sed

cu

lver

t w

ill

pas

s

Q100 f

low

at

HW

/D =

1.5

an

d

has

5 +

tim

es t

he

cap

acit

y o

f

the

exis

tin

g c

ulv

ert.

Sm

all

creek

ju

st e

ast

of

Wil

dm

an's

Sto

re.

See

ms

un

der

size

d;

slo

pe

cou

ld b

e st

eep

er.

D1

3

yes

3

.0

1.0

1

%

0.6

0

15

6

4

77

1

12

30

1

80

6

0 w

/fil

l

Eq

uiv

alen

t ca

pac

ity w

ith

ou

t

fill

is

less

th

an t

he

48 i

nch

es

req

uir

ing Q

100 a

nal

ysi

s.

Fo

llo

ws

dit

ch a

lon

g s

ou

th s

ide

of

Ste

rlin

g H

igh

way.

Exis

tin

g c

ulv

ert

is u

nd

er t

he

Snu

g H

arb

or

Ro

ad.

D1

4

0

.2

0.0

5

9%

0

.10

3

1

4

17

2

6

1

85

3

6

V

ery s

mal

l gro

und

wat

er-f

ed d

itch

dra

inag

e.

D1

5

3

.0

1.5

1

5%

0

.41

1

1

46

5

6

82

0

S

mal

l p

erm

anen

t st

ream

on

all

uvia

l fa

n w

ith

co

bb

le

bo

tto

m.

Co

mb

ined

wit

h D

16.

D1

6

1

.0

1.0

2

0%

0

.41

1

1

46

5

6

82

17

0

36

Sm

all

stre

am

; sa

me

allu

via

l fa

n a

s D

15

.

D1

7

2

.0

1.0

2

0%

0

.41

1

1

46

5

6

82

0

S

mal

l st

ream

; sa

me

allu

via

l fa

n a

s D

15

and

D16

.

Co

mb

ined

wit

h D

16.

D1

8

1

.0

0.3

9

%

0.0

1

0

1

2

3

17

0

36

S

mal

l st

ream

fed

by s

pri

ng 1

00 f

t ab

ove

alig

nm

ent.

Mu

ck b

ott

om

.

D1

9

8

.0

1.5

1

2%

0

.60

1

5

64

7

7

11

2

1

75

4

2

M

id-s

ized

str

eam

wit

h D

50

of

8 i

nch

es.

D2

0

1

.5

0.8

1

0%

0

.06

2

9

1

1

17

17

5

36

Sm

all

stre

am

wit

h o

rgan

ic b

ott

om

. (

no

rib

bo

n h

un

g)

D2

1

3

.0

1.0

1

7%

0

.08

2

1

2

14

2

2

15

5

36

M

id-s

ized

str

eam

in

rav

ine

(100

ft

wid

e b

y 2

0 f

t

dee

p).

D

50

is

2 i

nch

es.

D2

2

1

.5

1.5

1

0%

0

.11

3

1

5

18

2

7

1

60

3

6

S

teep

, n

arro

w c

han

nel

wit

h g

ravel

bott

om

(D

50

=1

in

).

D2

3

3

.0

1.0

2

5%

0

.69

1

7

72

8

7

12

6

22

0

42

S

mal

l, s

teep

dra

inag

e in

V-g

ull

y (

10

0 f

t w

ide

and

20

ft d

eep

)

D2

4

N

A

NA

0

%

un

del

inea

ted

1

60

3

6

L

oca

l d

rain

age.

D2

5

yes

4

.0

1.0

1

%

0.1

8

5

22

2

7

40

12

5

48

w/f

ill

Eq

uiv

alen

t ca

pac

ity w

ith

ou

t

fill

is

less

th

an t

he

48 i

nch

es

req

uir

ing Q

100 a

nal

ysi

s.

Sm

all

low

gra

die

nt

stre

am t

hat

par

alle

ls s

ou

th s

ide

of

road

fo

r ap

pro

xim

atel

y 4

00

ft.

P

erh

aps

fish

.

Hydro

logy a

nd H

ydra

uli

cs

Sum

mary

Ste

rlin

g H

ighw

ay M

P 4

5 t

o 6

0 P

roje

ct

6

ID

Fish Stream

OHW Width (ft)

OHW Depth (ft)

Slope (%)

Basin Area (sq

miles)

Q2 (cfs)

Q50 (cfs)

Q100 (cfs)

Q500 (cfs)

Existing Culvert

Size (in)

Proposed Culvert

length (ft)

Proposed Culvert

Size (in)

Q100 F

lood

ev

alu

ati

on

for

culv

erts

wit

h e

qu

ivale

nt

size

gre

ate

r th

an

48

”

Fie

ld N

ote

s

Coo

per

Cre

ek

Alt

ern

ati

ve

(con

tin

ued

)

D5

7-D

77

(se

e C

oop

er C

reek

an

d G

So

uth

alt

ern

ativ

es)

D9

6-D

10

6 (

see

All

alt

ern

ativ

es)

G S

ou

th A

lter

nati

ve

D1

-D9

(se

e A

ll a

lter

nat

ives

)

D2

6-D

49

(se

e Ju

nea

u C

reek

an

d G

So

uth

alt

ern

ativ

es)

D5

0

yes

2

.5

1.0

5

%

0.5

2

13

5

6

68

9

9

43

0

54

w/f

ill

Eq

uiv

alen

t ca

pac

ity w

ith

ou

t

fill

is

less

th

an t

he

48 i

nch

es

req

uir

ing Q

100 a

nal

ysi

s.

Sam

e st

ream

as

D7

8 w

ith

co

bb

le b

ott

om

. C

ulv

ert

at

road

cro

ssin

g d

ow

nst

ream

is

36

" in

dia

met

er.

D5

1

1

.0

0.2

1

%

0.5

3

13

5

8

69

1

01

17

0

42

S

mal

l d

rain

age;

lik

ely i

nte

rmit

ten

t.

Act

ual

slo

pe

is <

1%

.

D5

2

yes

4

.0

2.0

1

%

0.6

9

17

7

2

87

1

25

0

L

ow

ban

k i

n m

arsh

y a

rea.

P

oss

ibly

a f

ish

str

eam

.

Par

alle

ls a

lign

men

t.

D5

3

yes

4

.0

2.0

1

%

0.6

9

17

7

2

87

1

25

15

0

60

w/f

ill

Eq

uiv

alen

t ca

pac

ity w

ith

ou

t

fill

is

less

th

an t

he

48 i

nch

es

req

uir

ing Q

100 a

nal

ysi

s.

Str

eam

par

alle

ls t

he

alig

nm

ent

bet

ween

D5

2 a

nd

D5

3.

D5

4

2

.0

1.5

8

%

0.3

7

10

4

2

51

7

5

20

5

36

D

ry s

trea

m b

ed w

ith

gra

vel

bo

ttom

in

lar

ge

allu

via

l

fan

.

D5

5

2

.0

0.1

1

%

un

del

inea

ted

24

0

36

S

mal

l sp

rin

g f

ed s

trea

m;

as

mu

ch s

pri

ng f

ed m

arsh

as

stre

am

. A

ctu

al s

lop

e <

1%

.

D5

6

yes

2

.0

0.6

1

%

0.1

9

5

24

2

9

43

22

5

36

S

mal

l st

ream

th

rou

gh

mar

sh w

ith

san

dy b

ott

om

.

Po

ssib

ly f

ish

hab

itat

. A

ctu

al s

lope

< 1

%.

D5

7-D

77

(se

e C

oop

er C

reek

an

d G

So

uth

alt

ern

ativ

es)

D9

6-D

10

6 (

see

All

alt

ern

ativ

es)

Ju

neau

Cre

ek

Alt

ern

ati

ve

D1

-D9

(se

e A

ll a

lter

nat

ives

)

D2

6-D

49

(se

e Ju

nea

u C

reek

an

d G

So

uth

alt

ern

ativ

es)

D7

8

yes

5

.0

1.2

1

8%

0

.52

1

3

56

6

8

99

54

0

54

w/f

ill

Eq

uiv

alen

t ca

pac

ity w

ith

ou

t

fill

is

less

th

an t

he

48 i

nch

es

req

uir

ing Q

100 a

nal

ysi

s.

Bra

nch

of

Bea

n C

reek

. C

obb

le b

ott

om

(D

50

=6 i

n).

D7

9

1

.0

1.5

1

%

0.1

2

3

16

2

0

30

23

0

36

Sm

all

stre

am

th

at d

rain

s w

etla

nd

.

D8

0

2

.0

1.5

2

%

0.3

0

8

35

4

3

63

23

0

36

Sm

all,

E c

han

nel

; vel

oci

ty 1

.5 f

t/s.

D8

1

1

.5

3.0

1

%

0.4

8

12

5

3

63

9

2

17

5

36

B

ean

Cre

ek;

smal

l, E

ch

ann

el,

vel

oci

ty a

pp

roxim

atel

y

1 f

t/s.

A

ctu

al s

lop

e <

0.0

1.

Hydro

logy a

nd H

ydra

uli

cs

Sum

mary

Ste

rlin

g H

ighw

ay M

P 4

5 t

o 6

0 P

roje

ct

7

ID

Fish Stream

OHW Width (ft)

OHW Depth (ft)

Slope (%)

Basin Area (sq

miles)

Q2 (cfs)

Q50 (cfs)

Q100 (cfs)

Q500 (cfs)

Existing Culvert

Size (in)

Proposed Culvert

length (ft)

Proposed Culvert

Size (in)

Q100 F

lood

ev

alu

ati

on

for

culv

erts

wit

h e

qu

ivale

nt

size

gre

ate

r th

an

48

”

Fie

ld N

ote

s

Ju

neau

Cre

ek

Alt

ern

ati

ve

(con

tin

ued

)

D8

2

6

.0

2.0

1

%

1.5

0

36

1

40

16

7

23

8

15

0

54

No

pri

vat

e la

nd o

r st

ruct

ure

s

up

stre

am.

Flo

od h

azar

d

min

imal

. F

oo

d w

ater

s w

ill

bac

kw

ater

to

hei

gh

t o

f fi

ll.

Sm

all

to m

od

erat

ely s

ized

str

eam

wit

h g

rav

el b

ott

om

(D5

0=

1 i

n).

D8

3

1

2.0

1

.5

2%

3

.26

7

5

27

3

32

2

45

1

17

0

72

Dra

inag

e B

asin

no

t cl

earl

y

def

ined

. W

ill

req

uir

e fu

rth

er

stu

dy.

No

pri

vat

e la

nd o

r

stru

ctu

res

up

stre

am.

Flo

od

haz

ard

min

imal

. F

ood

wat

ers

wil

l b

ack

wat

er t

o h

eigh

t o

f

fill

.

Mo

der

ate

size

d s

trea

m w

ith

gra

vel

bott

om

(D

50

=2

in).

V

elo

city

is

app

roxim

atel

y 5

ft/

s.

D8

4

5

.0

0.5

1

%

0.4

2

11

4

7

57

8

3

13

0

36

S

mal

l to

mo

der

atel

y s

ized

und

istu

rbed

str

eam

wit

h

san

d b

ott

om

. A

pp

roxim

atel

y 1

ft/

s fl

ow

.

D8

5

3

.0

0.5

2

%

0.0

4

1

6

7

11

25

0

36

Dra

inag

e B

asin

no

t cl

earl

y

def

ined

. W

ill

req

uir

e fu

rth

er

stu

dy.

Sam

e st

ream

as

D8

6.

Ro

ad a

lignm

ent

par

alle

ls

stre

am

; co

uld

mo

ve

cen

terl

ine

uph

ill

100

ft?

D8

6

3

.0

0.5

7

%

0.0

4

1

6

7

11

0

Dra

inag

e B

asin

no

t cl

earl

y

def

ined

. W

ill

req

uir

e fu

rth

er

stu

dy.

Sm

all

stre

am

in

bro

ad r

avin

e.

Loggin

g h

as d

istu

rbed

stre

am

bed

(w

idth

an

d d

epth

are

qu

esti

on

able

). S

ame

stre

am

as

D8

5,

kee

p s

trea

m o

n s

ou

th s

ide

of

RO

W.

D8

7

N

A

NA

0

%

un

del

inea

ted

1

30

3

6

S

eep

.

D8

8

3

.0

0.5

1

7%

0

.33

8

3

8

46

6

7

2

65

3

6

N

arro

w r

avin

e w

ith

bed

rock

wal

ls.

D8

9

2

.0

1.0

3

8%

0

.03

1

5

6

9

18

0

36

S

mal

l st

ream

; d

iver

ted

fro

m o

rigin

al s

trea

m b

ed b

y

loggin

g r

oad

. O

rigin

al s

trea

m b

ed

2 f

t w

ide

by 1

ft

dee

p (

ban

k f

ull

).

D9

0

N

A

NA

1

8%

0

.07

2

1

0

12

1

9

1

40

3

6

D

ry s

trea

m b

ed;

has

no

t h

ad f

low

fo

r se

ver

al y

ears

.

D9

1

3

.0

1.0

3

5%

0

.34

9

3

9

47

7

0

17

0

36

S

mal

l st

eep

str

eam

. A

ch

ann

el w

ith

lar

ge

cob

ble

bo

tto

m a

nd

bro

ad r

avin

e.

D9

2

4

.0

0.2

6

%

0.1

3

4

18

2

2

32

16

5

36

S

mal

l st

ream

w/

surf

ace

& s

ub

surf

ace

flo

w.

18

" C

MP

culv

ert

in o

ld r

oad

in

suff

icie

nt;

hig

h w

ater

has

over

top

ped

. H

ou

se p

its

on

bo

th s

ides

of

stre

am

.

D9

3

2

.0

0.2

1

%

un

del

inea

ted

18

3

00

3

6

S

mal

l lo

cal

dra

inag

e.

18

in

CM

P c

ulv

ert

un

der

ro

ad.

Hydro

logy a

nd H

ydra

uli

cs

Sum

mary

Ste

rlin

g H

ighw

ay M

P 4

5 t

o 6

0 P

roje

ct

8

Ju

neau

Cre

ek

Alt

ern

ati

ve

(con

tin

ued

)

D9

4

yes

2

.5

1.5

1

%

0.4

3

11

4

8

58

8

5

11

0

54

w/f

ill

Eq

uiv

alen

t ca

pac

ity w

ith

ou

t

fill

is

less

th

an t

he

48 i

nch

es

req

uir

ing Q

100 a

nal

ysi

s.

Des

ign

may c

ho

ose

to

kee

p

this

str

eam

no

rth

of

the

road

in w

Lo

w g

rad

ien

t st

ream

wit

h s

and

y b

ott

om

(ac

tual

slo

pe

< 1

%).

P

oss

ible

fis

h h

abit

at.

Str

eam

ju

st t

ou

ches

RO

W t

hen

tu

rns

bac

k t

o t

he

NW

.

D9

5

yes

2

0.0

3

.0

0.0

%

0.5

2

13

5

7

68

9

9

B

rid

ge

Bri

dge

S

trea

m/p

on

d/w

etla

nd

co

mp

lex.

D9

6-D

10

6 (

see

All

Alt

ern

ativ

es)

Coo

per

Cre

ek

a

nd

G S

ou

th A

lter

nati

ves

D5

7

N

A

NA

1

%

0.3

8

10

4

3

52

7

6

24

1

45

3

6

S

mal

l lo

w g

rad

ien

t st

ream

. A

ctu

al

slo

pe

< 1

%.

D5

8

yes

N

A

NA

2

%

1.1

7

28

1

13

13

5

19

3

36

1

10

6

6 w

/fil

l

Po

nd

-wet

lan

d c

om

ple

x

up

stre

am,

no

str

uct

ure

s.

Flo

od

haz

ard

fro

m

bac

kw

ater

min

imal

. T

wo

sm

all

stre

am

s fl

ow

in

to p

ond

ab

ove

culv

ert.

D5

9

N

A

NA

un

del

inea

ted

24

1

50

3

6

L

oca

l d

rain

age;

may n

ot

be

nec

essa

ry.

D6

0

N

A

NA

un

del

inea

ted

24

1

45

3

6

L

oca

l d

rain

age;

dra

ins

to n

ort

h.

D6

1

N

A

NA

un

del

inea

ted

1

80

3

6

N

ow

flo

w p

rese

nt.

C

ulv

ert

may n

ot

be

nec

essa

ry.

D6

2

N

A

NA

un

del

inea

ted

24

1

40

3

6

N

o s

trea

m;

loca

l.

D6

3

N

A

NA

un

del

inea

ted

24

1

15

3

6

N

o s

trea

m;

loca

l.

D6

4

6

.0

0.0

1.7

1

41

1

57

18

6

26

5

36

1

15

6

0

Wil

l p

ass

Q100 flo

od

at

WH

/D =

1.5

. S

om

e p

ote

nti

al

for

flo

od

ing o

f p

rivat

e

pro

per

ty u

pst

ream

. P

ropo

sed

culv

ert

is 3

tim

es t

he

cap

acit

y o

f th

e ex

isti

ng

stru

ctu

re.

S

mal

l st

ream

.

D6

5

N

A

NA

un

del

inea

ted

24

1

05

3

6

L

oca

l d

rain

age.

D6

6

yes

1

0.0

1

.5

4%

3

.78

8

6

31

0

36

5

51

0

24

/36

1

05

1

14 w

/fil

l

Pro

po

sed

cu

lver

t w

ill

pas

s

Q500 fl

ood

at

WH

/D =

1.5

Cu

lver

t is

und

ersi

zed

(o

ver

flo

w 2

4"

CM

P i

nst

alle

d o

ff

to s

ide)

. M

od

erat

e st

ream

wit

h c

ob

ble

bo

tto

m

(D5

0=

6 i

n).

P

oss

ible

fis

h p

assa

ge

issu

es:

hig

h

vel

oci

ty &

pin

ched

do

wn

stre

am o

pen

ing.

Des

ign

ed

for

HW

/D=

1,

Pri

vat

e p

rop

erty

in

flo

od

pla

in u

pst

ream

.

D6

7

yes

5

.5

1.0

2

%

0.1

3

3

17

2

0

31

2

4

11

0

60

Dra

inag

e B

asin

no

t cl

earl

y

def

ined

. W

ill

req

uir

e fu

rth

er

stu

dy.

Sm

all

stre

am

.

D6

8

N

A

NA

un

del

inea

ted

24

1

25

3

6

D

itch

dra

inag

e an

d s

eep

.

D6

9

N

A

NA

un

del

inea

ted

24

1

25

3

6

D

itch

dra

inag

e.

D7

0

N

A

NA

un

del

inea

ted

24

1

25

3

6

D

itch

dra

inag

e an

d s

eep

.

D7

1

N

A

NA

5

%

0.5

1

13

5

5

66

9

7

24

1

20

4

2

S

mal

l st

eep

str

eam

.

Hydro

logy a

nd H

ydra

uli

cs

Sum

mary

Ste

rlin

g H

ighw

ay M

P 4

5 t

o 6

0 P

roje

ct

9

Coo

per

Cre

ek

an

d G

Sou

th A

lter

nati

ves

(co

nti

nu

ed

)

D7

2

N

A

NA

un

del

inea

ted

24

1

10

3

6

D

itch

an

d s

eep

dra

inag

e.

Inle

t o

f cu

lver

t is

bu

ried

.

D7

3

N

A

NA

un

del

inea

ted

24

1

10

3

6

S

po

rtsm

an's

Lan

din

g;

dra

ins

to t

he

no

rth

.

D7

4

N

A

NA

un

del

inea

ted

24

1

10

3

6

D

itch

dra

inag

e.

D7

5

N

A

NA

0.3

5

9

40

4

9

71

2

4

13

0

36

S

mal

l st

ream

ap

pro

xim

atel

y 6

0 f

t w

est

of

culv

ert

dra

ins

alon

g d

itch

to c

ulv

ert.

D7

6

N

A

NA

un

del

inea

ted

24

1

20

3

6

D

itch

dra

inag

e.

Cu

lver

t in

let

is p

arti

ally

bu

ried

.

D7

7

N

A

NA

0.1

4

4

19

2

3

34

3

0

10

5

36

Sm

all

stre

am

; st

eep

exit

slo

pe

at o

utl

et.

Ju

neau

Cre

ek

an

d G

Sou

th A

ltern

ati

ves

D2

6

5

.0

1.0

2

0%

0

.77

1

9

79

9

5

13

7

23

0

48

Pro

po

sed

cu

lver

t w

ill

pas

s

Q100 flo

od

at

WH

/D =

1.5

.

Sm

all

can

yo

n a

pp

roxim

atel

y 1

00

ft

wid

e an

d 2

0 f

t

dee

p.

(no

fla

ggin

g h

un

g)

D2

7

1

.0

1.0

1

4%

0

.19

5

2

4

29

4

2

22

5

36

S

mal

l v

alle

y a

pp

roxim

atel

y 5

0 f

t w

ide

and

6 f

t d

eep

.

(no

fla

ggin

g h

un

g)

D2

8

2

.0

1.0

2

0%

0

.22

6

2

7

32

4

8

30

0

36

V

-can

yo

n 2

00

ft

wid

e an

d 5

0 f

t dee

p.

San

d a

nd

gra

vel

bo

tto

m.

(no

fla

ggin

g h

un

g)

D2

9

4

.0

1.0

3

0%

0

.74

1

8

76

9

1

13

2

14

5

48

Pro

po

sed

cu

lver

t w

ill

pas

s

Q100 f

loo

d a

t W

H/D

= 1

.5.

Ste

ep n

arro

w c

anyo

n,

no

bac

kw

ater

flo

od

haz

ard

to

stru

ctu

res

or

pri

vat

e la

nd

s

Ste

ep A

ch

ann

el;

bed

rock

or

larg

e co

bble

s.

Do

wn

stre

am

cu

lver

t 2

4”.

D3

0

N

A

NA

1

4%

u

nd

elin

eate

d

1

45

3

6

S

trea

m r

un

s su

rfac

e an

d s

ub

surf

ace

alo

ng d

rain

age.

D3

1

N

A

NA

2

0%

u

nd

elin

eate

d

16

0

36

S

trea

m s

ub

surf

ace

; la

rge

cott

on

wo

od

s; p

ho

to 1

82

9

sho

ws

dra

inag

e b

asin

.

D3

2

N

A

NA

un

del

inea

ted

1

65

3

6

S

eep

D3

3

N

A

NA

un

del

inea

ted

1

75

3

6

S

eep

D3

4

N

A

NA

un

del

inea

ted

2

00

3

6

S

eep

D3

5

N

A

NA

1

7%

u

nd

elin

eate

d

1

65

3

6

S

mal

l st

ream

D3

6

N

A

NA

un

del

inea

ted

1

85

3

6

S

eep

D3

7

N

A

NA

un

del

inea

ted

1

85

3

6

S

eep

D3

8

N

A

NA

un

del

inea

ted

1

90

3

6

S

eep

D3

9

N

A

NA

un

del

inea

ted

1

90

3

6

S

eep

D4

0

N

A

NA

1

6%

u

nd

elin

eate

d

1

55

3

6

D

efin

ed d

rain

age;

su

rfac

e an

d s

ub

surf

ace

flo

w.

D4

1

N

A

NA

1

7%

u

nd

elin

eate

d

1

40

3

6

S

ame

as D

40

D4

2

N

A

NA

0

%

un

del

inea

ted

1

60

3

6

S

eep

D4

3

N

A

NA

1

3%

u

nd

elin

eate

d

1

45

3

6

S

ame

as D

40

D4

4

N

A

NA

un

del

inea

ted

1

65

3

6

S

eep

D4

5

N

A

NA

un

del

inea

ted

1

60

3

6

S

eep

D4

6

N

A

NA

2

0%

u

nd

elin

eate

d

1

90

3

6

S

ame

as D

40

D4

7

N

A

NA

un

del

inea

ted

2

00

3

6

S

eep

Hydro

logy a

nd H

ydra

uli

cs

Sum

mary

Ste

rlin

g H

ighw

ay M

P 4

5 t

o 6

0 P

roje

ct

10

Ju

neau

Cre

ek

an

d G

Sou

th A

ltern

ati

ves

(co

nti

nu

ed

)

D4

8

1

.0

0.6

3

%

un

del

inea

ted

2

00

3

6

S

mal

l d

rain

age

wit

h m

ud

bo

tto

m.

D4

9

2

.0

1.2

5

%

un

del

inea

ted

20

0

36

E

ch

ann

el (

smal

l) w

ith

su

bsu

rfac

e t

o s

urf

ace

flo

w.

Mu

d b

ott

om

.

All

Alt

ern

ati

ves

D1

NA

N

A

u

nd

elin

eate

d

24

1

55

3

6

D

itch

dra

inag

e.

D2

NA

N

A

u

nd

elin

eate

d

24

1

35

3

6

D

itch

dra

inag

e.

D3

4.0

1

.3

13

%

0.3

4

9

40

4

8

70

3

6

17

0

36

Sm

all

stre

am

; p

erch

ed 2

ft

at o

utl

et.

D4

NA

N

A

u

nd

elin

eate

d

24

2

60

3

6

N

o f

low

fo

r yea

rs.

Exit

s at

to

p o

f st

eep

slo

pe?

D5

2.0

1

.0

7%

0

.25

7

3

0

37

5

4

36

1

85

3

6

S

mal

l st

ream

.

D6

NA

N

A

10

%

0.2

8

7

33

4

0

59

2

4

18

0

36

S

mal

l st

ream

lo

cate

d 5

0 f

t ea

st o

f C

MP

. O

utl

et i

s

per

ched

. N

ew c

ulv

ert

sho

uld

be

pla

ced

dia

go

nal

ly

acro

ss r

oad

.

D7

NA

N

A

u

nd

elin

eate

d

12

1

45

3

6

D

itch

dra

inag

e.

D8

NA

N

A

u

nd

elin

eate

d

24

1

60

3

6

D

itch

dra

inag

e.

D9

NA

N

A

u

nd

elin

eate

d

36

1

35

3

6

L

oca

l d

rain

age

wit

h n

o f

low

(n

one

for

yea

rs).

D9

6

N

A

NA

un

del

inea

ted

24

1

75

3

6

D

itch

dra

inag

e.

D9

7

3

.0

1.0

3

%

0.4

3

11

4

8

58

8

5

1

85

3

6

S

mal

l st

eep

str

eam

50

ft

no

rth

of

road

wit

h s

and

bo

tto

m.

D9

8

N

A

NA

un

del

inea

ted

24

1

50

3

6

D

itch

dra

inag

e.

D9

9

N

A

NA

un

del

inea

ted

24

1

50

3

6

D

rain

age

dit

ch.

D1

00

N

A

NA

1

0%

0

.67

1

3

53

6

4

92

2

4

13

0

42

M

od

erat

e si

zed

str

eam

wit

h s

eco

nd

str

eam

lo

cate

d

10

0 f

t w

est.

C

ulv

ert

un

der

size

d;

over

flo

ws

to e

ast.

Per

ched

at

ou

tlet

and

wat

erfa

ll o

n n

ort

h s

ide.

D1

01

N

A

NA

0.2

2

6

27

3

3

48

2

4

14

5

36

Dit

ch d

rain

age

and s

mal

l cr

eek.

D1

02

6

.0

1.2

2

%

0.4

3

11

4

8

58

8

4

36

1

30

3

6

S

mal

l cr

eek

wit

h f

alls

on

no

rth

(up

stre

am)

sid

e o

f

road

. W

idth

and

dep

th m

easu

rem

ents

are

fo

r

do

wn

stre

am

po

rtio

n o

f cr

eek.

D1

03

N

A

NA

un

del

inea

ted

24

1

25

3

6

D

itch

dra

inag

e.

D1

04

yes

1

6.0

1

.0

3%

3

.22

6

8

24

2

28

5

39

9

36

1

50

B

rid

ge

No

pri

vat

e la

nd o

r st

ruct

ure

s

in u

pst

ream

bac

k w

ater

are

a.

Fu

ller

Cre

ek,

Mod

erat

e st

ream

par

alle

ls r

oad

fo

r 20

0

ft f

rom

eas

t.

Cu

lver

t u

nd

ersi

zed

, w

ith

hig

h-w

ater

mar

k 4

ft

abo

ve

top

, o

f cu

lver

t, f

loo

din

g t

op

of

road

.

Str

eam

par

alle

ls r

oad

on

so

uth

fo

r 2

00

fee

t w

est.

Lar

ge

sed

imen

t tr

ansp

ort

D1

05

N

A

NA

0.2

8

7

33

4

0

60

2

4

15

0

36

C

ulv

ert

dra

ins

mar

shy a

rea.

Cu

lver

t in

ver

t p

lugged

and

abo

ve

level

of

mar

sh

D1

06

N

A

NA

un

del

inea

ted

24

1

75

3

6

C

ulv

ert

in d

ry a

rea.

D

ow

nst

ream

en

d s

ho

ws

flo

w.

OH

W -

Ord

inar

y H

igh

Wat

er.

Q2 -

Flo

od d

isch

arge

wit

h 5

0%

year

ly r

ecu

rren

ce p

rob

abil

ity.

HW

/D -

Dep

th o

f b

ackw

ater

(ab

ove

inver

t)/d

iam

eter

of

culv

ert.

Q

50 -

Flo

od d

isch

arge

wit

h 2

% y

ear

ly r

ecu

rren

ce p

rob

abil

ity.

NA

- D

rain

ages

wit

h l

ow

or

no

flo

w a

nd

/or

ind

efin

ite

dra

inag

e ch

ann

el.

Q100 -

Flo

od d

isch

arge

wit

h 1

% y

earl

y r

ecu

rren

ce p

rob

abil

ity.

Q

500 -

Flo

od d

isch

arge

wit

h 0

.2%

yea

rly r

ecu

rren

ce p

rob

abil

ity.



11

7.0 HYDRAULICS

7.1 Drainages with Delineated Basins

Preliminary culverts sizes were selected to convey the 50-year flood (Q50) flow across the

roadway in accordance with the DOT&PF Highway Preconstruction Manual Section 1120.4,

January 1998, for drainages with delineated drainage basins. Conveyances with an equivalent

diameter exceeding 48 inches were also evaluated for Q100 flood conveyance. The Q100 evaluation

is included as a separate column in Table 1. All pipe sizes are listed for guidance only. Final

flood flows, fish passage requirements, and size and type of the conveyance structures, as well as

the appurtenant features such as headwalls and erosion control will be determined during the

final design.

The proposed culverts were sized using the Federal Highway Administration Hydraulic Design

Series No. 5, Hydraulic Design of Highway Culverts (dated 1985). The following assumptions

were used in these calculations:

• Culvert is operating under inlet control. This assumption may not hold for long culverts

on a flat slope whose size is determined by the Q50 or Q100 events. This assumption must

be checked during the design.

• Culvert entrance type is mitered to conform to the upstream road embankment.

• Headwater condition is equal to 1.5 times the height of the culvert (HW/D = 1.5). HW/D

was reduced to 1.0 in two drainages, one to prevent buildup of sediment upstream of the

conveyance in an actively eroding stream channel, and the second to prevent flooding of

private property. These drainages are noted in Table 1.

All sizing guidance on fish stream conveyances were designed to meet the ADF&G/DOT&PF

Memorandum of Agreement (MOA) Tier 1 requirements dated August 29, 2001. These sizes

should be considered approximate as final design may elect to meet the requirements of other

tiers under this memorandum.

The recommended capacity of equivalent fish passage culverts was evaluated using the same

assumptions. The hydraulic capacity of partially filled round culverts was estimated using the

flow capacities of dimensionally equivalent pipe-arch culverts. Table 2 gives the estimated

capacities of culverts. This table was used to select culverts for the Q50 flood flows. Pipe-arch

culverts were not used in the preliminary sizing guidance. Culvert use in specific locations will

be dictated by cover requirements and fill depths of the final design.



12

Table 2: Culvert Flood Flow Capacities

7.2 Drainages with Undelineated Basins

Culverts for undelineated basins were sized using minimum DOT&PF-specified culvert sizes.

These sizes are 24 inches for culverts less than 100 feet in length and 36 inches for culverts

greater than 100 feet in length. All conveyance structures were determined to be longer than 100

feet. The 50-year flood flow capacity of the 36-inch culvert equates to a drainage basin of

approximately ½-square mile, this exceeds the size of all the undelineated basins. Many basins

are no more than a few acres. With one exception (D10) all drainages that cross the existing

roadway were sized to meet or exceed the size of the existing conveyance. The existing culvert at

D10 may be oversized to alleviate winter ice build up. The recommended pipe size for this

drainage is based on projected flood flows only.

Non Fish Passage Culverts Fish Passage Culverts

Round

Culvert

(inches)

Calculated

Capacity

(cfs)

Round w/

40% Fill

(inches)

Approximate

Equivalent Pipe-

arch (inches)

Estimated

Capacity

w/fill (cfs)

24 19 36 36x22 25

30 32 42 43x27 40

36 52 54 50x31 57

42 75 60 58x36 83

48 105 66 65x40 110

54 140 72 72x44 140

60 180 78 73x55 200

72 290 84 84x61 265

78 350 96 98x69 370

84 425 114 114x77 510



13

8.0 FISH PASSAGE CONSIDERATIONS

Fish-bearing streams were delineated as described in section 5.0. Nine fish-bearing streams are

identified along the three build alternatives. One of these streams (Cooper Creek) will be

spanned by a bridge for the project. A second stream (Fuller Creek) is also a recommended

bridge site although this may change during design analysis. Culverts for the remaining crossings

were sized to meet the ADF&G/DOT&PF MOA Tier 1 requirements for fish passage. To meet

Tier 1 requirements, the culvert width shall be 90 percent of the stream channel width at ordinary

high water with channel slopes greater than 1%. Culverts may be installed at slopes less than

0.5% with culvert widths equal or greater than 75% of the ordinary high water width, in streams

with slopes less than 1%. Round culverts should be embedded below the stream substrate to 40

percent of their depth and pipe-arch culverts shall be buried at least 20% of the rise. At some

crossings this width requirement dictates the culvert size while on others the Q50 flood flow

capacity dictates the culvert size. A different approach to culvert sizing may be proposed subject

to provisions of Title 41 and consultation with state and federal agencies during the actual permit

application and review process.

The following sections address each fish-bearing stream and the flood flow and fish passage

parameters governing culvert design. Drainages are listed in numerical order.



14

8.1 Drainage Site D13 (Cooper Creek Alternative)

Shown on Map Figure 4

This stream currently runs in a ditch alongside the Sterling Highway, crosses under the Snug

Harbor Road and empties into Kenai Lake upstream of the Cooper Landing Bridge. Final design

should address the possibility of rerouting this stream directly to the Kenai River across Kenai

Borough lands. The current configuration causes continual maintenance and icing problem.

• Base flow channel width = 30 inches

• Slope = 1%

• Width at ordinary high water = 36 inches

• Drainage basin area = 0.60 square miles

• Q50 = 64 cfs

• Culvert width to meet State MOA Tier 1 fish passage requirement = 36 inches

• Round culvert size to meet Q50 capacity with 40 percent fill = 60 inches

• Estimated culvert length= 180 feet

• Flood flow capacity controls the size of this conveyance design

Figure 13: Drainage site D13, upstream side

of Snug Harbor Road crossing.

Figure 12: Drainage site D13, downstream

side of Snug Harbor Road crossing.



15

8.2 Drainage Site D25 (Cooper Creek Alternative)



• Slope = 1%



• Q50 = 24 cfs

• Culvert width to meet MOA Tier 1 fish passage requirement = 48 inches



• Fish passage width controls the size of this conveyance design

Figure 14: Drainage site D25, downstream side

of existing road crossing.

Figure 15: Drainage site D25, upstream side of

existing road crossing.



16

8.3 Drainage Site D50 (G South Alternative) and D78 (Juneau Creek Alternative),

Tributary to Bean Creek


• D50 is on the G South Alternative just upstream of D78, crossing site features are similar


• Slope = 4%

• D50 = 6 inches



• Estimated culvert length D50, 540 feet and D78, 430 feet

• Q50 = 56 cfs



• Flood flow capacity and fish passage width both control the size of this conveyance

design

Figure 17: Drainage site D78.




17

8.4 Drainage Site D56 (G South Alternative)



• Slope = 1%

• D50 = Sand



• Q50 = 24 cfs








18

8.5 Drainage Sites D52 and D53 (G South Alternative), Main Stem of Bean Creek

Shown on Map Figures 5 and 7

The stream parallels the alignment and touches the alignment at two locations. Only one

conveyance should be required. Fisheries survey did not find fish at this crossing but this stream

is listed as an anadromous stream in the ADF&G 2004 Anadromous Streams Catalog.


• D50 = 1 inch



• Q50 = 72 cfs




Figure 19: Drainage sites D52 and D53.



19

8.6 Drainage Site D58 (Cooper Creek - G South alternatives)


This stream drains a small stream/pond complex on the outside of a low speed corner next to the

Kenai River. It was the site of a petroleum tanker truck spill 3 years ago but has gotten clean

closure from the state Department of Environmental Conservation.

• Base flow channel width = Small pond (n/a)

• Slope = 0%

• Width at ordinary high water = Small pond (n/a)


• Q50 = 113 cfs

• Culvert width to meet MOA Tier 1 fish passage requirement = Stream width not

applicable. Tier II design should be considered for this conveyance.



• Flood flow capacity control the size of this conveyance design

Figure 20: Drainage site D58 upstream side of


Figure 21: Drainage site D58 downstream side




20

8.7 Drainage Site D66 (Cooper Creek - G South alternatives)



• Slope = 4%

• D50 = 8 inches



• Q50 = 309 cfs





Figure 22: Drainage site D66, downstream side






21

8.8 Drainage Site D67 (Cooper Creek - G South Alternatives)



• Slope = 2%

• D50 = 3 inches



• Q50 = 17 cfs





Figure 24: Drainage site D67, downstream

side of existing road crossing.





22

8.9 Drainage Site D94 (Juneau Creek Alternative)


This stream was not surveyed as part of the HDR fisheries evaluation. It is included here as a

fisheries stream crossing but should be sampled to determine its status. This stream flows into

the stream/pond complex that becomes D95. Final design may keep this stream north of the road

in which case no conveyance will be needed.


• Slope = 1%



• Q50 = 48 cfs








23

8.10 Drainage Site D95 (Juneau Creek Alternative)


This stream/pond was not surveyed as part of the HDR fisheries investigation. It is included here

as a fisheries stream crossing because of apparent fisheries habitat and fish observed during the

H&H field investigation. This site will fall at a major intersection of highways. Its final

configuration and recommended conveyance will ultimately depend on the layout of this

intersection, how much the road fill encroaches into the stream/pond complex, and other factors

as yet unknown. The drainage basin and flood flows are small compared to the width of the

existing channel; channel grade is near 0%. Tier II analysis could reduce the requirement of this

site to a single pipe-arch structure of modest size.

• Base flow channel width = 20 feet

• Slope = 0%

• Width at ordinary high water = 20-25 feet


• Q50 = 57 cfs

• Width to meet MOA Tier 1 fish passage requirement = 15 feet. Tier II criteria should be

considered for final design.


• Estimated length= NA

• Fish passage width may control the size of this conveyance design




24

8.11 Drainage Site D104 (All Alternatives); Fuller Creek


Because of the ongoing sediment transport issues surrounding this structure a bridge should be

considered for this site. Fuller creek has moved west to the extreme edge of its alluvial fan

perhaps by previous road work. The stream is incising into the old alluvial fan 200 yards above

the road and depositing the sediments as it slows just above the road crossing. Any structure that

reduces velocity in this area is will continue this problem. A more detailed analysis should be

done during final design.


• Slope = 3%



• Q50 = 242 cfs

• Width to meet MOA Tier 1 fish passage requirement = 180 inches


• Estimated length= 150 feet


Figure 28: Drainage site D104, upstream reach showing gravel deposition.



25

Figure 29: Drainage site D104, downstream side of existing road crossing.

Figure 30: Drainage site D104, upstream side of existing road crossing.



26

9.0 REFERENCES

Alaska Department of Fish and Game (ADF&G) and Alaska Department of Natural Resources.

2004. Atlas and Catalog of Waters Important for the Spawning, Rearing, or Migration of

Anadromous Fishes.

ADF&G and Alaska Department of Transportation and Public Facilities (ADOT&PF). 2001.

Memorandum of Agreement (MOA) between the Alaska Department of Fish and Game and

the Alaska Department of Transportation and Public Facilities for the Design, Permitting and

Construction of Culverts for Fish Passage, dated August 29, 2001.

ADOT&PF. 1995. Alaska Highway Drainage Manual, 1st Edition June 1995.

ADOT&PF. 1998. ADOT Highway Preconstruction Manual.

Federal Highway Administration. 1985 Hydraulic Design Series No. 5, Hydraulic Design of

Highway Culverts.

HDR Alaska, Inc. 2004. Sterling Highway Milepost 45 to 60 draft Fisheries Evaluation,

November 2004.

United States Department of Commerce. 1963. Probable Maximum Precipitation and Rainfall

Frequency Data for Alaska, Technical Paper No. 47.

United States Geological Survey (USGS). Estimating the Magnitude and Frequency of Peak

Streamflows for Ungaged Sites on Streams in Alaska and Conterminous Basins in Canada,

USGS Water-Resources Investigation Report 03-4188.

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