Applied Geology and Geophysics Used in the

Widening of New Hampshire’s Interstate 93

-By Michael O’Brien----Geological Intern, Bureau of Materials & Research, NHDOT-

1. CADD & GPS

2. Strike & Dip of Bedrock

Joints and Foliation

3. Test Borings

7. Conclusion

4. Ground Penetrating Radar

5. Seismic Refraction

6. Resistivity Methods

0

n=1

(Rou

te 1

11 O

rient

atio

n)

n=10

1 (O

utcr

op J

oint

ing)

Num

tota

l: 13

2

n=1

(Tre

nd o

f Out

crop

)

n=29

(R

ock

Out

crop

F

olia

tion)

Geo

phon

e ho

oked

to a

sei

smic

line

. T

his

line

used

12

geop

hone

s an

d w

as

com

bine

d w

ith a

n ad

ditio

nal l

ine

of 1

2 ge

opho

nes.

The

num

ber

of s

hots

are

de

pend

ent u

pon

the

grou

nd c

ondi

tions

an

d sp

acin

g of

the

geop

hone

s bu

t a

min

imum

of t

hree

equ

ally

spa

ced

shot

s ar

e no

rmal

ly r

equi

red

for

inte

rpre

tabl

e da

ta.

Thi

s lin

e re

quire

d se

ven

shot

s;

two

offs

et s

hots

pas

t the

end

s of

the

line,

two

end

shot

s, a

nd th

ree

shot

s eq

ually

spa

ced

alon

g th

e lin

e.

The

Bet

sy G

un is

inse

rted

into

the

grou

nd

appr

oxim

atel

y tw

o fe

et.

The

Bet

sy g

un

cons

ists

of a

long

met

al r

od w

ith a

sho

tgun

sh

ell a

ttach

ed to

an

open

end

. A

ham

mer

w

ith a

met

al ti

p is

then

use

d to

str

ike

a m

etal

pie

ce o

n th

e to

p of

the

gun.

Bot

h m

etal

pie

ces

are

fitte

d w

ith a

wire

that

w

hen

conn

ecte

d cr

eate

s a

sign

al th

at is

di

rect

ly s

ent t

o th

e re

cord

er.

The

sig

nal

star

ts th

e ac

quis

ition

of d

ata

colle

cted

from

th

e ge

opho

nes.

The

str

ike

and

dip

data

is s

umm

ariz

ed o

n a

ster

eone

tusi

ng a

com

pute

r pr

ogra

m.

For

this

pro

ject

we

used

Ste

reoN

ettv

ersi

on

2.1

by J

ohan

nes

Duy

ster

. T

hest

ereo

neti

s he

lpfu

l in

plot

ting

the

folia

tion

(gre

en)

and

join

ts (

blac

k)of

the

expo

sed

bedr

ock.

T

he p

ropo

sed

road

way

is a

lso

plot

ted

on th

est

ereo

net(

red)

. T

hest

ereo

netd

ata

is th

en a

naly

zed

to d

eter

min

e th

e an

gle

of

cutb

ack

and

the

amou

nt o

f roc

k to

be

rem

oved

from

a r

ocks

sur

face

with

its

face

par

alle

l to

the

road

way

. If

the

prop

osed

ro

adw

ay c

hang

es d

irect

ion

with

in th

e sa

me

rock

uni

t the

cut

back

ang

le c

an c

hang

e as

join

ts a

nd fo

liatio

n be

com

e m

ore

or le

ss

para

llel w

ith th

e ro

ad.

Geo

logi

sts

will

rec

omm

end

to th

e en

gine

ers

wha

t ang

le th

e be

droc

k sh

ould

be

cut (

blas

ted)

bas

ed o

n th

e in

terp

reta

tion

of th

ese

ster

eone

ts.

The

am

ount

of m

ater

ial t

hat n

eeds

to b

e re

mov

ed is

ver

y im

port

ant f

or th

e st

ate

in

dete

rmin

ing

how

muc

h rig

ht o

f way

nee

ds to

be

purc

hase

d an

d to

pro

vide

cos

t est

imat

es.

0

Equ

al a

rea

proj

ectio

n, lo

wer

he

mis

pher

en=

1 (R

oute

111

Orie

ntat

ion)

n=8

(Out

crop

Joi

ntin

g)

Num

tota

l: 13

n=4

(Roc

k O

utcr

op F

olia

tion)

Ster

eogr

am o

f B

edro

ck F

olia

tion

and

Jo

intin

g A

long

Rou

te 1

11R

oad

Ori

enta

tion

(1)

@ 6

3 D

egre

esSt

atio

n 23

0+00

to

Stat

ion

233+

50

0

Equ

al a

rea

proj

ectio

n, lo

wer

he

mis

pher

e

Num

tota

l: 18

n=1

(Rou

te 1

11 O

rient

atio

n)

n=14

(O

utcr

op J

oint

ing)

n=3

(Roc

k O

utcr

op F

olia

tion)

The

sig

nal i

s se

nt to

a c

ompu

ter,

prin

ter,

or

othe

r da

ta c

olle

ctin

g so

urce

. W

here

it c

an

be s

tore

d or

ana

lyze

d.

Ster

eogr

am o

f B

edro

ck F

olia

tion

and

Join

ting

Alo

ng R

oute

111

Roa

d O

rien

tatio

n (2

) @

78

Deg

rees

Stat

ion

239+

00 t

o St

atio

n 25

3+00

Ster

eogr

am o

f B

edro

ck F

olia

tion

and

Jo

intin

g A

long

Rou

te 1

11

Roa

d O

rien

tatio

n (3

) @

89

Deg

rees

Stat

ion

252+

00 t

o St

atio

n 26

2+00

Bru

nton

Com

pass

. U

sing

the

Bru

nton

Com

pass

one

can

mea

sure

th

e st

rike

and

dip

of jo

ints

and

fo

liatio

n on

out

crop

s.

Mos

t of t

he d

ata

that

is c

olle

cted

by

geol

ogis

ts fo

r th

e de

velo

pmen

t of a

roa

dway

sys

tem

is ta

ken

afte

r ci

vil e

ngin

eers

des

ign

apr

elim

inar

y dr

aft o

f the

pro

pose

d ro

adw

ay.

In m

ost c

ases

the

prel

imin

ary

plan

s ar

e m

ade

usin

g C

ompu

ter

Aid

ed D

esig

n an

d D

rafti

ng

(CA

DD

). F

rom

this

dra

ft a

surv

ey c

rew

or

the

geol

ogis

ts th

emse

lves

sta

ke o

ut th

e al

ignm

ent o

f the

roa

d us

ing

the

Glo

bal P

ositi

onin

g S

yste

m (

GP

S).

Plo

t of t

he I-

93 s

outh

bou

nd

off r

amp,

exi

t 3.

The

bla

ck

“x”s

are

way

poin

ts s

how

ing

the

cent

er o

f the

new

off

ram

p to

be

built

. T

hese

w

aypo

ints

will

be

tran

sfer

red

to th

e G

PS

dat

a lo

gger

.

GP

S s

atel

lite.

Sat

ellit

es o

rbiti

ng th

e ea

rth

send

rad

io s

igna

ls to

the

GP

S

unit.

The

re a

re 2

4 no

n-ge

osta

tiona

ry

sate

llite

s at

an

altit

ude

of a

bout

26

,000

km

and

circ

le th

e ea

rth

appr

oxim

atel

y ev

ery

12 h

ours

. U

p to

12

sat

ellit

es a

re v

isib

le to

the

user

at

any

poin

t on

the

eart

h at

all

times

(c

anop

y an

d ob

stru

ctio

ns w

ill h

ampe

r th

e am

ount

the

rece

iver

can

pic

k up

). G

PS

dat

a lo

gger

. G

eolo

gist

s ta

ke th

e w

aypo

ints

that

hav

e be

en tr

ansf

erre

d on

to th

e G

PS

uni

t, an

d st

ake

them

out

. T

he p

ropo

sed

road

is n

ow a

ctua

lly

bein

g ph

ysic

ally

out

lined

in th

e fie

ld.

The

way

poin

ts s

take

d ou

t by

the

DO

T’s

ge

olog

ists

are

bas

ed s

tric

tly o

n th

e G

PS

un

it an

d th

eref

ore

are

an e

stim

ate

of th

e pr

opos

ed r

oad.

For

gre

ater

acc

urac

y,

the

cons

truc

tion

com

pany

will

sur

vey

the

way

poin

ts a

gain

dur

ing

the

road

s pr

oduc

tion.

Ful

l GP

S u

nit.

Thi

s un

it co

nsis

ts o

f a d

ata

logg

er w

hich

run

s a

“Win

dow

s” o

pera

ting

syst

em, m

uch

like

a sm

all h

andh

eld

com

pute

r. T

he d

ata

logg

er is

atta

ched

to a

re

ceiv

er (

ante

nna)

sho

wn

bein

g ca

rrie

d on

th

e ba

ck.

Way

poin

t sta

ke fo

und

on r

oute

111

in

Win

dham

. T

he L

T. m

eans

left

27 m

eter

s of

way

poin

t 279

0 +

20

or le

ft 20

met

ers

of

the

cent

er o

f the

pro

pose

d ro

ad.

2790

+

20 is

ess

entia

lly 2

0 m

eter

s pa

ssed

the

way

poin

t 279

0 or

279

0.20

.

By

usin

g th

e G

PS

, geo

logi

sts

no

long

er h

ave

to p

ace

and

com

pass

be

droc

k, b

ut c

an s

impl

e w

alk

arou

nd

the

edge

of a

n ou

tcro

p an

d th

e G

PS

w

ill r

ecor

d ea

ch s

tep.

The

x &

y e

rror

fo

r th

e G

PS

is +

/-on

e m

eter

. In

the

lab

one

can

dow

nloa

d th

ese

imag

es

and

plac

e th

em r

ight

on

the

CA

DD

dr

awin

g. G

eolo

gist

s ca

n al

so p

lot a

lin

e sh

owin

g w

here

geo

phys

ical

in

form

atio

n w

as ta

ken,

suc

h as

the

line

show

n in

the

pict

ure

abov

e.

To

build

a r

oad,

eng

inee

rs a

nd c

onst

ruct

ion

crew

s ne

ed to

kno

w w

hat l

ies

bene

ath

the

grou

nd. T

he a

mou

nt o

f mat

eria

l tha

t nee

ds to

be

rem

oved

is v

ery

impo

rtan

t for

the

stat

e in

det

erm

inin

g ho

w m

uch

right

-of-

way

nee

ds to

be

purc

hase

d.

In N

H, t

here

is n

orm

ally

soi

l and

un

derly

ing

glac

ial s

edim

ents

(sa

nd &

gra

vel,

till,

mar

ine

clay

) ab

ove

bedr

ock.

The

firs

t ste

p in

det

erm

inin

g th

is in

form

atio

n is

find

ing

and

map

ping

all

visi

ble

bedr

ock

outc

rops

. T

he p

rinci

pal r

ock

unit

is d

eter

min

ed a

nd th

en n

oted

on

the

GP

S d

ata

colle

ctor

for

each

map

ped

outc

rop.

If n

eede

d, a

sam

ple

is ta

ken

back

to th

e la

b w

here

a th

in s

ectio

n ca

n be

mad

e of

the

rock

. D

urin

g an

d or

afte

r th

e ou

tcro

ps a

re

map

ped,

a d

escr

iptio

n of

litho

logy

and

sele

ctio

n of

str

uctu

ral d

ata

(e.g

., st

rike

& d

ip o

f lay

erin

g, fo

liatio

n, a

nd jo

ints

) ar

e co

llect

ed.

The

geo

phys

ical

dat

a ar

e an

alyz

ed a

nd c

ombi

ned

with

the

info

rmat

ion

from

test

bor

ing

sam

ples

and

dat

a ob

tain

ed fr

om s

urfa

ce e

xpos

ures

, to

crea

te a

se

ries

of c

ross

-sec

tions

sho

win

g an

inte

rpre

ted

bedr

ock

line.

The

cro

ss-s

ectio

ns w

ill b

e pe

rpen

dicu

lar

to th

e pr

opos

ed r

oadw

ay a

nd a

t a s

et d

ista

nce

inte

rval

. T

he d

evel

oped

cro

ss-s

ectio

ns a

re th

en g

iven

to d

esig

n en

gine

ers

who

will

use

the

info

rmat

ion

to m

ake

deci

sion

s co

ncer

ning

the

amou

nt o

f m

ater

ial a

nd th

e ty

pe o

f mat

eria

l tha

t nee

ds to

be

rem

oved

and

thus

the

amou

nt o

f rig

ht-o

f-w

ay th

at w

ill n

eed

to b

e pu

rcha

sed.

T

here

are

pos

itive

s an

d ne

gativ

es a

bout

whe

ther

the

mat

eria

l tha

t nee

ds to

be

rem

oved

is b

edro

ck o

r so

il. I

f the

mat

eria

l is

dete

rmin

ed to

be

soil,

the

cutb

ack

angl

e w

ill b

e at

a s

hallo

w tw

o to

one

rat

io.

The

wor

k ca

n be

don

e by

the

gene

ral c

ontr

acto

r w

ith a

bul

ldoz

er a

nd e

xcav

ator

and

ther

efor

e be

le

ss ti

me

cons

umin

g an

d ch

eape

r. U

nfor

tuna

tely

, mor

e “r

ight

of w

ay”

will

nee

d to

be

purc

hase

d by

the

stat

e or

take

n by

“em

inen

t dom

ain”

. P

urch

asin

g m

ore

land

cou

ld m

ean

prob

lem

s w

ith ta

king

land

from

taxp

ayer

s, p

robl

ems

with

wet

land

s, e

tc.

If ro

ck, t

he c

utba

ck a

ngle

can

be

equa

l to

or le

ss th

an

83 d

egre

es d

ippi

ng to

war

ds th

e ro

ad.

One

of t

he p

ositi

ve a

spec

ts fo

r fin

ding

bed

rock

is th

at le

ss r

ight

-of-

way

nee

ds to

be

purc

hase

d by

the

stat

e. O

ne

of th

e ne

gativ

e as

pect

s is

that

bed

rock

has

to b

e bl

aste

d by

a li

cens

ed c

ompa

ny, w

hich

will

incr

ease

rem

oval

cos

ts.

Bla

sted

bed

rock

is h

arde

r to

re

mov

e th

an s

oil,

but i

t ofte

n ca

n be

use

d fo

r fil

l in

othe

r ar

eas

of th

e pr

ojec

t.

Pub

lic s

afet

y is

alw

ays

a co

ncer

n w

hen

desi

gnin

g an

d bu

ildin

g a

publ

ic r

oad

even

afte

r it

is b

uilt.

Kno

win

g w

hat a

ngle

to c

ut a

rock

s su

rfac

e ba

ck is

cr

itica

l to

the

publ

ic’s

saf

ety

for

a nu

mbe

r of

rea

sons

. G

ravi

ty is

con

stan

tly w

orki

ngto

rel

ease

sto

red

ener

gy in

roc

ks th

at m

ay b

e 50

to 1

00 fe

et a

bove

a

road

way

. If

not t

aken

into

acc

ount

, bed

rock

with

join

ting

syst

ems,

folia

tion,

and

oth

er p

lane

s of

frac

ture

s ca

n be

com

e ea

sily

disl

odge

d th

roug

h th

e pr

oces

s of

ero

sion

. T

hese

pla

nes

of w

eakn

ess

are

a ve

ry r

eal h

azar

d to

the

publ

ic.

For

thes

e re

ason

s, g

eolo

gist

s m

ust c

ontin

ually

mon

itor

rock

cut

s,

even

afte

r th

e ro

ck h

as b

een

cutb

ack

to th

e m

ost o

ptim

al a

ngle

and

dis

tanc

e fr

om th

e ro

ad.

The

vas

t maj

ority

of t

he e

arth

’s c

ontin

enta

l bed

rock

is c

over

ed b

y ov

erbu

rden

. O

verb

urde

n ca

n pr

oduc

e a

fals

e an

d un

clea

r im

age

of b

edro

ck d

epth

an

d sh

ape

of s

urfa

ce.

With

the

appl

icat

ion

of g

eoph

ysic

s ge

olog

ist a

re a

ble

to p

rovi

de a

sub

surf

ace

pict

ure

of th

e ea

rth’

s be

droc

k in

are

as o

f int

eres

t to

civi

l eng

inee

rs.

Thi

s sa

ves

time,

mon

ey a

nd h

elps

to m

aint

ain

publ

ic s

afet

y.

Dril

l rig

in S

alem

, NH

con

duct

ing

a te

st b

orin

g.

A te

st b

orin

g w

ill p

rovi

de g

eolo

gist

s a

smal

l bu

t exa

ct w

indo

w o

f wha

t is

belo

w th

e gr

ound

. W

hen

com

bine

d w

ith th

e ge

ophy

sics

dat

a, a

de

taile

d cr

oss-

sect

ion

can

be d

evel

oped

of

the

area

s su

bsur

face

con

ditio

ns.

A s

plit-

spoo

n be

ing

poun

ded

into

the

grou

nd.

The

spl

it-sp

oon

is a

hol

low

ed

met

al tu

be (

pict

ured

to th

e rig

ht).

Whe

n dr

iven

into

the

grou

nd b

y th

e dr

ill r

ig, i

t w

ill c

olle

ct a

sam

ple

of th

e so

il be

low

. T

he n

umbe

r of

blo

w c

ount

s de

term

ines

th

e de

nsity

of t

he s

oil.

The

blo

w c

ount

is

the

num

ber

of “

blow

s”it

take

s fo

r a

free

falli

ng 1

40 p

ound

wei

ght f

allin

g 30

in

ches

to m

ove

the

split

-spo

on 1

2 in

ches

into

the

grou

nd.

The

hig

her

the

blow

cou

nt is

the

dens

er th

e m

ater

ial.

An

open

spl

it-sp

oon

reve

alin

g th

e co

llect

ed s

oil.

G

eolo

gist

s re

cord

the

colo

r, p

artic

le s

ize

and

reco

very

(le

ngth

of t

he c

olle

cted

sam

ple)

. T

he

split

-spo

on is

pou

nded

two

feet

into

the

grou

nd,

the

reco

very

is th

en th

e am

ount

(le

ngth

) of

soi

l co

llect

ed fr

om th

at tw

o fe

et.

A s

ampl

e is

take

n fr

om s

omew

here

w

ithin

the

split

-spo

on.

The

sam

ple

is

labe

led

and

plac

ed in

ord

er o

f dep

th.

Roc

k co

re. D

epen

ding

upo

n th

e de

pth

of th

e dr

ill h

ole,

be

droc

k w

ill e

vent

ually

be

reac

hed.

A c

ore

sam

ple

is

take

n to

det

erm

ine

the

rock

uni

t and

its

phys

ical

ch

arac

teris

tics.

Tes

t bor

ings

are

a v

ery

help

ful t

o ge

olog

ists

and

eng

inee

rs b

y ex

posi

ng m

ater

ial o

ther

wis

e in

acce

ssib

le.

Tes

t bor

ings

allo

w g

eolo

gist

s to

see

the

subs

urfa

ce a

nd c

an r

evea

l the

dep

th to

whi

ch s

oil l

ayer

s or

bed

rock

are

exp

ecte

d. G

eoph

ysic

al m

etho

ds c

an h

elp

dete

rmin

e w

here

test

bor

ings

nee

d to

be

cond

ucte

d or

test

bor

ings

can

be

used

to d

eter

min

e w

here

add

ition

al d

ata

are

need

ed

thro

ugh

geop

hysi

cal m

etho

ds.

Sei

smic

ref

ract

ion

is a

geo

phys

ical

pro

cess

bas

ed o

n th

e tr

avel

tim

es a

nd d

ista

nce

ofco

mpr

essi

onal

wav

es th

roug

h an

unk

now

n m

ater

ial.

Com

pres

sion

alw

aves

are

cre

ated

by

an e

nerg

y so

urce

(N

HD

OT

use

s a

Bet

sy G

un).

The

se w

aves

are

then

mea

sure

d by

geo

phon

es

plac

ed a

t kno

wn

dist

ance

s fr

om th

e bl

ast.

The

sei

smic

ene

rgy

prop

agat

es th

roug

h th

e gr

ound

and

is r

efra

cted

as

it tr

avel

s th

roug

h di

ffere

nt la

yers

of m

ater

ial.

The

24

geop

hone

s pi

ck u

p th

e re

frac

ted

com

pres

sion

wav

es a

nd th

e am

ount

of t

ime

it ta

kes

the

wav

es to

re

ach

each

geo

phon

e. C

ompr

essi

on w

aves

trav

el a

t diff

eren

t spe

eds

depe

ndin

g on

the

med

ium

that

they

are

trav

elin

g th

roug

h, th

usa

dens

e m

ater

ial s

uch

as b

edro

ck w

ill s

how

com

pres

sion

alw

aves

that

trav

el m

uch

fast

er a

s co

mpa

red

to th

ose

of a

loos

e la

yer

of s

and.

500

MH

z G

PR

uni

t. T

his

unit

and

mos

t GP

R u

nits

, con

sist

s of

a c

ontr

ol

unit,

a c

ompu

ter

for

colle

ctin

g da

ta,

and

tran

smitt

ing

and

rece

ivin

g an

tenn

as.

A G

PR

uni

t bei

ng p

ulle

d th

roug

h th

e w

oods

whi

ch c

reat

es a

sub

surf

ace

prof

ile

that

can

be

view

ed d

urin

g th

e tr

aver

se.

Res

ults

of G

PR

dat

a di

spla

yed

on a

lapt

op

com

pute

r.

Gro

und

Pen

etra

ting

Rad

ar is

a g

eoph

ysic

al to

ol u

sed

whe

n be

droc

kis

exp

ecte

d to

be

shal

low

and

the

over

burd

en h

as li

ttle

to n

o cl

ay o

r si

lt. T

he G

PR

uni

t wor

ks b

y se

ndin

g el

ectr

omag

netic

wav

es in

to th

e gr

ound

from

a tr

ansm

ittin

g an

tenn

a. T

he w

aves

pen

etra

te th

egr

ound

and

trav

el a

ppro

xim

atel

y 3-

30 ti

mes

slo

wer

than

the

spee

d of

ligh

t, de

pend

ing

upon

the

elec

tric

al p

erm

ittiv

ity o

f the

mat

eria

l.

The

ele

ctro

mag

netic

wav

es a

re r

efle

cted

bac

k to

a r

ecei

ving

ant

enna

and

are

am

plifi

ed w

ithin

the

cont

rol u

nit a

nd d

ispl

ayed

on

the

com

pute

r sc

reen

.

Fin

al r

esul

ts o

f the

GP

R tr

aver

se in

W

indh

am, N

H.

The

x-a

xis

is d

ista

nce

in

met

ers,

the

y-ax

is is

dep

th in

met

ers.

The

re

d lin

e re

pres

ents

the

inte

rpre

ted

star

t of

bedr

ock

as fo

und

from

ana

lyzi

ng th

e da

ta.

The

line

sho

ws

that

the

bedr

ock

is v

ery

shal

low

onl

y ab

out 1

to 2

met

ers

belo

w th

e su

rfac

e.

Res

istiv

ity m

etho

ds a

re fo

und

by p

assi

ng a

dire

ct c

urre

nt in

to th

e gr

ound

bet

wee

n tw

o el

ectr

odes

, C1

and

C2.

Tw

o m

ore

elec

trod

es

(P1

and

P2)

that

do

not c

arry

a c

urre

nt, m

easu

re th

e di

ffere

nce

of v

olta

ge c

ause

d by

the

curr

ent.

Res

istiv

ity m

etho

ds w

ork

wel

lin

mat

eria

ls th

at a

re m

ore

cond

uctiv

e th

an r

esis

tive.

In

the

field

the

com

pute

r is

mea

surin

g ho

w r

esis

tive

laye

rs o

f mat

eria

l are

.It

shou

ld b

e no

ted,

this

is th

e ap

pare

nt r

esis

tivity

not

the

true

res

istiv

ity w

hich

is fo

und

by a

com

pute

r pr

ogra

m th

at p

rodu

ces

a be

st

leas

t squ

are

fit b

etw

een

the

appa

rent

and

the

calc

ulat

ed r

esis

tivity

.

Res

istiv

ity li

ne.

Thi

s re

sist

ivity

line

w

as c

ompo

sed

of tw

o lin

es

conn

ecte

d in

the

mid

dle

by a

co

ntro

l box

. E

ach

line

cont

aine

d 24

el

ectr

odes

for

a to

tal o

f 48

elec

trod

es.

Diff

eren

t arr

ays

can

be

set u

p to

loca

te C

1, C

2, P

1, a

nd

P2.

Onl

y fo

ur e

lect

rode

s op

erat

e at

a

time

and

larg

e nu

mbe

rs o

f re

adin

gs a

re ta

ken

alon

g th

e lin

e.

Clo

se u

p of

one

of t

he e

lect

rode

s. E

ach

elec

trod

e is

seq

uent

ially

test

ed to

mea

sure

its

gro

und

resi

stan

ce in

Koh

m.

For

opt

imal

re

sults

1-3

Koh

mar

e w

ante

d, 4

-20

Koh

mar

e re

adab

le, b

ut 2

1 an

d hi

gher

are

un

usab

le.

If th

e te

st r

un p

rodu

ces

num

bers

hi

gher

than

21

Koh

m, s

altw

ater

is p

oure

d on

the

elec

trod

e to

hel

p lo

wer

the

num

ber

by in

crea

sing

the

cond

uctiv

ity o

f the

soi

l.

Run

ning

the

resi

stiv

ity u

nit.

The

fina

l pro

duct

is p

rodu

ced

by a

n in

vers

ion

prog

ram

bac

k in

the

lab.

The

to

p cr

oss-

sect

ion

is th

e ap

pare

nt r

esis

tivity

, cal

cula

ted

resi

stiv

ity (

mid

dle)

, an

d in

vers

ion

or tr

ue r

esis

tivity

(bo

ttom

). R

ed h

as a

muc

h hi

gher

Ohm

.m

read

ing

mak

ing

it a

mor

e re

sist

ive

mat

eria

l. T

he b

lue

show

s lo

wO

hm.m

an

d is

the

mos

t con

duct

ive

mat

eria

l. In

gen

eral

con

duct

ive

mat

eria

ls a

re

that

of c

lay

(1-1

00 o

hm.m

), s

and

(4-8

00 o

hm.m

), e

tc.

Whi

le r

esis

tive

mat

eria

ls, s

uch

as r

ock

are

gran

ite (

3x10

^2 –

10^6

ohm

.m),

sha

le (

6x10

^2

–4x

10^7

ohm

.m),

etc

. A

ll m

ater

ials

will

be

mor

e co

nduc

tive

whe

nw

et.

Rou

te 1

11 in

Win

dham

–S

alem

. T

he p

ictu

re

was

take

n on

Aug

ust 1

8th20

04 a

few

thou

sand

ya

rds

from

the

pict

ure

to th

e le

ft. S

take

s m

arki

ngth

e bo

unda

ries

of th

e ne

w r

oad

can

be s

een

alon

g w

ith r

emov

ed b

edro

ck a

t the

cen

ter

of th

e pi

ctur

e. T

he e

xcav

ated

roc

k w

as u

sed

as a

larg

e fil

l und

erne

ath

the

soil

in th

e fo

refr

ont o

f the

ph

otog

raph

.

Diff

eren

t roa

d an

gles

alo

ng th

e pr

opos

ed R

t. 11

1, W

indh

am, N

H a

t exi

t 3 o

ff of

I-93

. R

ock

outc

rops

hav

e be

en m

appe

d in

bro

wn.

Inte

rsta

te I-

93 is

an

impo

rtan

t nor

thea

st c

orrid

or, c

onne

ctin

g th

e st

ates

of V

erm

ont,

New

Ham

pshi

re a

nd

Mas

sach

uset

ts.

Inte

rsta

te 9

3 ex

tend

s 21

0 m

iles

from

St.

John

sbur

y, V

T in

the

nort

h, th

roug

h 14

2 m

iles

in N

ew

Ham

pshi

re (

incl

udin

g th

e ci

ties

of C

onco

rd a

nd M

anch

este

r) a

nd e

nds

in D

edha

m, M

a. T

he o

rigin

al in

ters

tate

w

as b

uilt

in th

e 19

60's

and

can

hol

d a

max

imum

vol

ume

of 6

0 to

70

thou

sand

veh

icle

s pe

r da

y. T

he

Dep

artm

ent o

f Tra

nspo

rtat

ion

(DO

T)

in N

H fo

und

that

in 1

997

ther

e w

as a

n av

erag

e of

105

,000

veh

icle

s tr

avel

ing

per

day

on th

e se

ctio

n of

I-93

in S

alem

and

60,

000

to 8

0,00

0 ve

hicl

es tr

avel

ing

per

day

thro

ugh

segm

ents

nor

th o

f Exi

t 1 in

Sal

em. D

OT

traf

fic p

roje

ctio

ns r

evea

led

that

by

2020

, 140

,000

veh

icle

s pe

r da

y w

ould

trav

el o

r pa

ss th

roug

h th

e al

read

y ve

ry c

onge

sted

and

dan

gero

us s

tret

ch o

f I-9

3 in

Sal

em.

The

sta

te o

f NH

put

fort

h pl

ans

to b

uild

two

mor

e la

nes

both

nor

th a

nd s

outh

bou

nd o

n I-

93 fr

om th

e bo

rder

of N

ew H

amps

hire

and

Mas

sach

uset

ts in

Sal

em, N

H to

the

I-93

/I-29

3 in

ters

ectio

n in

Man

ches

ter,

NH

. T

he p

roje

ct w

ill e

xpan

d 18

mile

s of

inte

rsta

te a

nd ta

ke te

n ye

ars

to c

ompl

ete

at a

n es

timat

ed c

ost o

f 420

mill

ion

dolla

rs. T

he p

roje

ct w

ill b

e on

e of

the

larg

est c

onst

ruct

ion

jobs

in N

ew E

ngla

nd w

hile

und

er c

onst

ruct

ion.

T

he E

ngin

eerin

g/G

eolo

gy s

ectio

n of

the

DO

T w

ill p

lay

a la

rge

role

in th

e pl

anni

ng o

f I-9

3. B

efor

e th

eex

pans

ion

of I-

93 c

an ta

ke p

lace

a g

reat

dea

l of p

relim

inar

y ge

olog

ical

dat

a m

ust b

e co

llect

ed. T

o bu

ild a

roa

d pr

oper

ly e

ngin

eers

and

con

stru

ctio

n co

mpa

nies

nee

d to

gat

her

criti

cal g

eolo

gic

data

incl

udin

g th

e so

il ty

pe a

nd

dept

h to

bed

rock

. T

his

post

er r

evie

ws

seve

ral i

mpo

rtan

t dat

a co

llect

ing

step

s ne

eded

for

mak

ing

info

rmed

dec

isio

ns o

n th

e am

ount

and

type

of m

ater

ial t

o be

rem

oved

dur

ing

the

road

s co

nstr

uctio

n. A

ll of

the

data

and

info

rmat

ion

was

co

llect

ed a

long

Rt.

111

near

Exi

t 3, I

-93

and

alon

g th

e so

uthb

ound

off

ram

p of

Exi

t 3 in

Win

dham

, NH

.

Thi

s gr

aph

is d

ispl

ayin

g tw

o di

ffere

nt la

yers

of m

ater

ial b

elow

the

eart

h’s

surf

ace.

The

dar

k bl

ue la

yer

reve

als

a m

ater

ial w

ith a

muc

h sl

ower

co

mpr

essi

on v

eloc

ity o

f 400

to 6

00 m

eter

s pe

r se

cond

. T

he g

reen

to r

ed

colo

rs h

ave

a m

uch

high

er a

vera

ge v

eloc

ity o

f app

roxi

mat

ely

1800

-420

0 m

/s.

The

hig

her

the

prop

agat

ion

velo

city

with

in a

mat

eria

l, th

ede

nser

th

e m

ater

ial w

ill b

e. T

his

grap

h ca

n be

inte

rpre

ted

as h

avin

g a

laye

r of

so

il (b

lue)

cov

erin

g ve

ry s

hallo

w b

edro

ck (

gree

n) d

ippi

ng s

light

ly to

the

sout

heas

t.

Key

Inte

rsta

te 9

3 so

uth

and

nort

h bo

und

lane

s

Rou

te 1

11

Bed

rock

out

crop

s

Line

s w

here

geo

phys

ical

dat

a w

ere

take

n

Pro

pose

d w

iden

ing

of In

ters

tate

93

and

the

new

R

oute

111

alig

nmen

t

Pro

pose

d C

AD

D d

raw

ings

of

I-93

wid

enin

g an

d ne

w a

lign

men

t of

Rt.

111

at e

xit 3

in

Win

dham

, NH

.N

H R

oute

111

Wes

t of E

xit 3

in W

indh

am, N

H.

Abstract

Map

of p

ropo

sed

I-93

wid

enin

g an

d co

nstr

uctio

n of

two

railw

ay tr

acks

.

6

4

4

4

5

Res

ourc

es*A

ll of

the

abov

e da

ta w

as c

olle

cted

and

ana

lyze

d b

y M

icha

el O

’Brie

n an

d M

arc

Fis

h du

ring

the

sum

mer

of 2

004,

util

izin

g N

HD

OT

equ

ipm

ent.

NH

Dep

artm

ent o

f Tra

nspo

rtat

ion.

http

://w

ebst

er.s

tate

.nh.

us/d

ot/1

0418

c.de

faul

t.htm

C

FLH

D a

nd B

lack

haw

k G

eoS

ervi

ces.

“A

pplic

atio

ns o

f G

eoph

ysic

al M

etho

ds to

Hig

hway

Rel

ated

Pro

blem

s”.

Tec

hnic

al M

anua

l 200

2-20

03.

Sep

tem

ber

2003

.

CADD Drawing of Proposed I-93 Widening

and Route 111 New Alignment

Windham NH

Nor

thw

est

Sout

heas

t

Nor

thw

est

Sout

heas

t

Nor

thw

est

Sout

heas

t

Rou

te 1

11 in

Win

dham

-S

alem

(th

is c

onst

ruct

ion

site

is e

ast o

f exi

t 3 a

nd is

not

at t

he s

ite o

f our

co

llect

ed d

ata

but i

s st

ill a

part

of t

he R

t. 11

1 ne

w

alig

nmen

t).

Dril

l rig

is d

rillin

g pr

oduc

tion

blas

t ho

les

for

the

cons

truc

tion

of th

e ro

ck c

ut.

Stat

e m

ap o

f N

ew H

amps

hire

.

Key

Maj

or I

nter

stat

es

Stat

e M

aint

aine

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und

to th

e no

rth

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Rt.

111

in W

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The

ig

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area

.

m e t e r s