Sediment supply and transmission via roadside gully pots

63

The Science of the Total Environment, 33 (1984) 213-224 Elsevier Science PublishersB.V., Amsterdam-Printedin The Netherlands

SEDIMENT

SUPPLY

AND TRANSMISSION

VIA

ROADSIDE

C.J. PRATT' and J.R.W. ADAMS' 1 Department of Civil and Structural Engineering, Trent Polytechnic, Nottingham, NGl 4BU, (United 2 Pollution Control'Dept., Boots PLC., Nottingham,

GULLY

POTS

Kingdom) (United

Kin.gdom)

ABSTRACT Field studies undertaken on the Clifton Grove residential estate, between August 1976 and October 1980, in which the Nottingham, input and release of material to and from roadside gullies and the gully pot liquor quality were monitored, are reported. Factors affecting sediment supply, such as variations in soil moisture. deficit, rainfall parameters, runoff volume and catchment characteristics are considered, Sediment retention by gullies and,its release in storm flows are assessed in the light of the nature of the sediments found in basal samples from gully pots and in runoff sample% obtained downstream in the storm sewer. The effect of sediment input on gully liquor quality and the variation in dissolved oxygen concentration are detailed. The suspended sediment concentration in road surface/gully pot discharges-showed no clear tendency to decrease through a storm event and this, coupled with previous findings from storm simulations, strongly suggest that effects are a function of the flushing of in-pipe' "first flush" deposits from a previous storm event. INTRODUCTION Urban storm drainage research has been conducted,on the Clifton since 1976 and,in that time aspects of Grove catchment, Nottingham, both the quality and quantity of stormwater runoff have been The catchment has a total area of 10.6ha' investigated (ref.l-5). of which 42% are impervious highway and roof surfaces, draining to a separately-sewered storm drainage system. The roads, pavements and driveways, which drain to the sewer system, represent, elmast half of the total impervious surface area. Built between 1973 and 1976, the Estate is spaciously arranged;\, with areas of open land interspersing the rows of housing .along,gide 1 cul-de-sacs and the loop, .feeder road (ref.133). ,There arme.266 detached houses and bungalows and an estimated population. of 9:G2, All the properties have front assuming one person per bedroom. the front gardens generally being open without rear gardens, and'

00489697/84/$03.00

81984Eleevie.r.ScienoePubliahersB.V.

214 walls

or

ways

allow The

hedges

separating

at

least

each

channels,

and

carriageway,

research catchment

the

purposes, The

paper of

water

quality

roadside

road,

roof

Although

monitored. obtained

may

composed

of

be

no

SEDIMENT

SUPPLY

TO

gully

in

grating, from

was

hoped of

overflow,

which

The 14

On

28-day

6

the

the

material

one

14-day

and

from

34

divided than

into 1250

cuttings masses

a

microns and

of

results

distance

from

and

600,

and was each

due

28A 84

from

washotf

components:

and

leaf total

inorganic

meshes into

sediments, sediments

changed its

to

after frame

gullies,

and data

otherwise

the

1980:

for

November

1’979;

gully

gullie 52

1979. in

debris, litter,

leading

October

October

(ref microns

event.

other

vandalism,

from

90 different

storm

the

the

collected organic

comprising

one

to

gully

below

and

clogging

frozen of

to

150

received pot

retaining

but

the

which

400,

and was

below

gully

avoid

all

cleaned

gully

the

1979

gullies

meshes,

satisfactorily 1979;

and

in

lost

August

meshes,

At was

paper;

organic

some

just

would

grating

collected.

material two

the

position

1250,

several

case was

worked

of

of

system

1980;

mass

the

estates,

the

into

washoft, the

August

January The

the

and were

identical,

entering

nylon

discharge of

use

period

from

in

conical to

occasion

system

which

discharges

between

sealed

five

seemed

one

monitored

apertures

that

was

collecting

of prior

had

sample

from

one

collecting

days.

in quality

residential

I\laterial

1). box,

box

meshes

fractions

were

Table

on

runofE

GULLIES

plastic

the

The

It

a

and

flows 3).

(see

storm

studies

are

this

activity.

catchments

1980

on

equipment.

liqour

are

which

footway

quality

monitoring

catchment

housing,

of

water

field

modern

of

kerb-

Pr evi 0u s

made

gully

catchments

the

runoff

for

two

total

other

middle-income commercial

collected

and

of

or

Five

of

185m

be

flow

gullies,

two

typical

industrial

October

findings

to

in

stormwater

studied of

gratings 2

drive-

household.

tarmacadam.

to

being

the

of

of

interference

reports

material

in

and

per

average

estimates

gullies,

the

on

aspect

gsrage

via

surfaced

allowed

to

without

input

both flow

has

footway: accommodated is

draining

are

overland

hydrographs

be

drainage

grating

(ref.4)

inlet

the

to

water

which

on

from

vehicles

surface

highway,

side

them

two

a

14-day

being flower which retained

period

petals, were

was

material

larger grass

the on

sum the

of meshes.

the

a

215 @rganic

debris

The the

supply

year

borne

of

and into

the in

Seasonal

variations

the

and

period

of

and

limited

plant

Erom low

Organic

an.d

as

and

barrier

or

by

found

path

of

rolling to

highway

flower

September.

restricted

The

gardening

accounted to

for

the

water

a

the

from

period

the

gullies

highway

surface

discharge

which

Only

when

December

and

during

between'the volume

clear

to

the

mass

of V

volume

sediment

upon

was of

washoff supply

the

to

total

gully. fell

there

period,

lie suspension

mass

sediment than

reported

runoff

the

face

there

14-day

the

that

deficit

14-day

However,

influencing

moisture was

the

is

kerb

in

the and

mobilisation

April,

in

events.

storm-

the

sediments

transported

by

of

the

been

the

be

surface

it

soil

has

channel,

factors

its

of

accummulate

to

moved

within

action

between

It the

transports

early

runoff

highway

readily mode

be

The

storm

the

and

the

high,

during correlation

upon

to

streams

no

be

predominant

kerbside

(ref.3).

more

their

surfaces.

the

gully

generally

may

believed

sediments

surface

washed

debris,

is

which in

dependent

the

the

located

to be

sediments within

organic forces,

inlets

against Once

the

the

gully

from

(ref.6).

is

the

runoff

in

of

to

input

have

sediments as

vehicle-generated to

a

Nay

presumably debris

not

leaf-fall

shedding

late and

April,

need

water-

monitored.

autumnal

summer

supply

organic

inorganic sediments,

transport water

the

was

and being

e.g.

from

throughout

debris

blown

evident and

to of

wind catchment

clearly

matter

variable

organic

(ref.3).

Whilst wind

was

gully

February

were

Some

debris

levels

period

nature

much

December

cutting

generally that

but

particular

grass

activity,

its

catchment.

were

October

petals

and

the

gullies,

originated

between

material

across

any

to

zero,

correlation,

sediment

between and

vashoff,

late that

SED,

and

not the

(ref.3).

Gully

6,

SED

=

0.005V

t

9.5

(r

=

0.37)

(1)

Gully

34,

SED

=

0.015V

t

16.7

(r

=

0.63)

(2)

=

0.63)

For

the

five

Average, Between

moisture particles

=

=

low 2oog, in onto

gullies,

0.017V

December

generally SED

monitored SED

(r and

e.g.

gully

6,

V =

4800

the

surrounding the

April,

the SED

litres.

highway

=

The areas by

natural

mass 3Og,

(3) of

V =

sediment 3200

binding

effect

limited

the forces.

vashoff litres; of

was gully

the

surface

dispersion

of

Limited

gardening

34,

216 activity

and

ing to

the

of

no

SED

and

-

washoff

4205 becomes

catchment and

One The

2800

extremely

the

of

sediments

4000

and

differences was

3.61

near

mass

and

of

sediment

washoff gully

34,

sediment

sediments.

without 6,

of

hydrology

rainfall.

28A,

34

identical

and

52,

despite

mass

the

collected

moisture would

the

interactions

of

gullies

results

and

e.g.

was

almost

soil

April

washoff

transport

mean

similar

From

year.

various

1980)

the

restrict-

Predicting

the

in

llad

in

conditions,

catchments:

0.066g.

these

zero,

as

were

part

considerable

April,

microns, the

!:

of

(ref.3).

collected

90

between

meshes

the

supply

(lo-24th

a

sediment

meteorological

period

masses

play

time

litres

complex,

influence

14-day

between

than

in sometimes

characteristics,

hydraulics

that

were

1' about

also

between

variations

volume for

at esisted

the

runoff

40

sediments

correlation

volume, similar

would

movement

dispersion

December

runoff at

pedestrian

seem

by

the

deficit

been

unlikely

to

other have

occurred.

Catchment

characteristics

Table washoff

2

details

for

the The

periods.

with

impervious

area,

number

catchment maximum

shortest

SEij --SED

= =

12.4

LmaY

SEij

=

45.9

SLmav

-

r?Eb

=

1.4

HOUSES

+

of

sediments

NattIre

route

1.6

Examination solids

total distribution

and with

volatile

namely, path

path the

length,

Lmax,

length,

SLmax

catchment,

house

well

from

HOUSES, the

Estate

mean and

the

assuming entrance.

0.99)

(4)

=

0.91)

(5)

30.8

(r

=

0.92)

(6)

39.8

(r

=

0.86)

(7)

was of

via

were

=

of

29% fraction

(g),

characteristics,

each

sediment

observation

(r

mesh-trapped

the

microns

of 26

(r

92%

90

and S!?n

drainage

151.6

the

4%

masses 19

washoff,

drainage

and to

of

283.2

on

only

150

volatile

-

about

contained the

-

of

retained

in

taken

IMPAREA

represented

maximum

served

the

14-day for

values

gully

the

mean

gullies

IMPAREA, on

houses

and

mean

the

slope of

median monitored

long-term

correlated

catchment

the five

sediment

sediments

1250, of

600

the

the

and

total

volatile meshes

7%

microns (1250

solids.

The

2%,

but

of

the

total and

that

90

which

microns),

remainder

trapped

repectively, with

90% sediment

their

nature

the

meshes, -

represented,

and sizes

400 mass

revealed

6%

volatile. mass. has

The This important

of

on the

total

217 TABLE

1

Catchment

characteristics

Gu 1 1 y location

of

n u mb e r

Impervigus area (m I HP i\ R E A

43a 53" SGa

140 290 313

)

465 103

111 248 176 213

a(ref.

1 R

b(ret.

3

TABLE

2

Mean

14-day

Clifton

4.2 4.3 4.0 2.9 1.4 0.7 4.9 4.3 4.4

29 3s 36 4s 26 23 38 36 40

1976

-

June

August

1979

-

October

masses

of

sediment

14-day

sediment

Oct.

upon

the

RETENTION

from 3).

Clifton mean

of

mesh-trapped

Comparing

1980.

washoff

to

washoff

into

POTS

mean

composition

area load

The

particle

bulk

roadside

gullies

on

(g)

25.4 215.4

gradings.of that,

of

by

density

sieve

shows

gully

Elean of 26 periods Oct. 4th 1979 - Oct. 9th 1980

Nottingham

of

catchment

sediments

4)

of

collected

Grove

the Table

1977.

GULLY

the

residential

with

83

characteristics

BY of

taken Table

11 11 21 153 11

249.2 130.2 172.9

retention

estimate

Clifton

the

of served via

36 6 S6

25.7

57 73

sample

Grove.

11.1

110

the

Clifton

Number houses in and

Elean of 19 periods 9th 1980

19 4.3

An

on

Nottingham.

lledian of 19 periods Jan. 3rd -

SEDIblENT

(see

Length Cm) L ma s

August

6 28A 34 52 84

see

Slope (%) S Lmax

7),

Grove,

bearing

monitored

R S),

Gully location number

on

gullies

was

diameter

a the

gullies

the

basal

assuming

gully

pots.

the

basal

sediments

was gully basal

the

Table the

gully

from

sedinents

Mean

in

a

particle 2)

gully

diameter

was

is

(ref.7

1770kg/m3)

sands,

0.7mm.

mesh-trapped pot

in

machine

(c.f.

(in and

obtained

emptying

1492kg/m3 1.75mm.

for

of

sediments reasonably

pots

218 TABLE

3

Composition *rea

of

of

basal

sediments

components:

Soluble

Volatile DOD (mg/g) COD (mg/g)

components:

pots

in

the

Clifton

solids

(2)

21.0 43.5 34711

Dissolved COD (mn/E)

solids(mg/g)

4.0 3.2

4

Comparison

of

14-day

sediment

washoff

Sieve (microns)

size

into

Aperture

in

gully

basal

deposits

and

gullies.

retained

Rasal (9) 140 280 200 160 110 110

TABLE

fractions

roadside

Mass

5000 2000 1000 500 300 300

on

sieve

sediments

Cram

llcg

sample

Mesh-trapped in 14 days

sediments washoff

(g)

60 60 180 500 140 60

5

Annual

mean

pots

in

concentrations

mg/l

for

of

contained

Suspended Dissolved COD ROD Dissolved Pll

solids solids

oxygen

location

43=

53=

86c

97‘

15 197 25 7.1 3.6 7.5

15 818 30 6.5 6.0 7.9

29 231 37 6.5 6.2 7.5

27 343 56 7.1 8.5 10.5

7),

August

1976

-

June

d(ref.

8),

August

1979

-

October

at

sediment

mass sediment sediments

of

retaining input

2mn

2mm would

be

sediments

wash-through less

individual

eullv

lmm

sieve

d

gd

2Sd

33

27 191 39

26 269 109

19 163 54

35

d

20 209 68

86

24 140 57

24 162 47

7.8

1980.

sediments,

four

required

to This

the

mass

diameter.

to

five

times

accummulate suggests retained

the

d

50d

1977.

retained. exceeds

than

for

number

'(reK.

effective

constituents

liquor.,

Gullv

Constituent

of

gully

Nottingham.

Insoluble

TABLE

from

the

mass

observed

that

the

mass

by

many

times

of for

219

G II I, I, I’

I, T Q I IO R (,I I1 A I, I ‘I’ 1

Gully but

liquor

across

quality

the

(ref.147).

been

Grove

Ta b I e s

and

5 a nd

found

to

catchment

6

vary,

not

between

di sp1Ry

results

only

seasonally,

ditferent

gullies

obtained

between

1976

19SO.

Effect

of

sediment

Comparison gullies

intercention

was

made

between

the

gully

no.5

6,

34,

52

(location

unmeshed

gullies

the

period

for

the

with

occasion

Lo

October

19SO

ol

gullies

in

lover

by

35

mean

exceeded

al though

not

two-thirds

gully

basal

not

gully

of

at

the

(as

basal

(reE.1);

the

rising

limb

150

and

90

a

grading

seems

likely

would

be

erence the

a

of

in Council,

in dissolved

was

On

one

meshed

pots

concentrations,

by

so

in

about

the If

gully

the

pots

than of

11%

at 1983,

funded

the

volatile

sediments,

300 sizes

experiment

the

150

between was

the

in

view

300

repeated

as

it -

of

grains,

90

the

micron diff-

tested,

associated

and with

the

discharge in

Science

peak and

Eraction,

in

Polytechnic by

the

with

stormwater

Trent

than of

street

for

others,

determining

investigated

September

and

out

between

and

sand

gully

less

hydrograph,

observed,

quartz

aspect in

city

latter of

1 l/s, washed

sediments pot

and

oE

artificially

wash-through

greater

This

and of

of

sizes 50mm

to

from

the

various

up

triangular

weight

outflows

with

observed

composed

gravities

of

rates

of

and

that

increments

percentage

times

be

the

accurately

re-suspended

20-minute

9%

fraction.

Variations The

the

specific

will

values COD

pots.

were

inElows

shown

flow

typical

sediments

that

commencing Research

were

(reE.ll). of

performance quality,

and

through

microns

volatile

meshed

pots,

sediments

sediment

directly

several in

of some

washed

with

3)

grading,

1 l/s,

microns

meshed

for

mean

in

determine

have

Table

using

sand

discharge

to

trapping

sediments and

constituted

86)

sample,

solids

the

possible

experiments

sediments

pot

the

monitoring

is a

of‘

dissolved in

50,

period

grollp

meshed

samples.

it ot

33,

concentration

unmeshed:

of adjacent,

Considering 14-day

the

of

25,

(ref.8).

in

lover

Laboratory

types.

on

the

pot,

3;%

quality and

(5,

each

solids

the

simultaneously

efficiency

f%

in

necessarily of

Without

+

suspended

that

liquor R 84)

catchments

groups

the

just

28A,

simil.nr

January two

consistently

a

has

Clilton

research and

Engineering

Swindon.

dissolved oxygen

oxygen concentration

concentration of

the

gully

pot

liquor

may

TABLE

6

Mean

quality

from

research

of

water between

stored

in

August

1976

Constituent

Number samples

Suspended solids Dissolved solids COD BOD Dissolved oxygen Ammoniacal nitrogen Nitrate nitrogen Chloride PH Calcium Sodium Potassium Lead (total) Lead (soluble) Zinc (total) Zinc (soluble) Copper (total) Copper (soluble) Cadmium Manganese Nickel Iron Chromium

243 261 176 195 63 266 263 220 201 246 221 221 31 11 74 29 28 7 26 19 19 19 19

be

a

and

useful type

of

saturation

to

of

daily

but

could

be or

DO

only

at

1.2mg/l), Mean 6)

25%

concentration

saturation

for values are

some long-term,

some of

no

DO

guidance

of as

to

2.5'C,

was

60%

and at

provide

to

the

the

will

year.

vary

and

they air

occur,

made

very.

hot

by

the

(ref.8).

saturation

(i.e.

fell temper-

which

respectively

20°C

of

that

minimum

might

the

according

Measurements showed

of

level

achieve

hence

surfaces

2.5'

of to

runoff the

and

6.5

temperatures

value to

3.5mg/l),

around

25'C

at

(i.e.

reason.

concentration

indicator

and

variations

levels unknown

455 17475 935 135 0 - 11.2 5.9 29.8 9800 6.3 - 12.9 272 5560 28 1.36 0.10 3.5 0.56 0.32 0.09 0.07 0.74 0.42 7.00 0.48

maximum

from 29.5'

between of

of

daily

runoff e.g.

31.2 335 63 7.6 6.0 1.0 2.0 268 8.0 31 125 3.8 0.058 0.032 0.65 0.10 0.012 0.05 0.058 0.21 0.07 1.08 0.05

temperatures

major

to

snowmelt

temperatures

but

the

occasional

the

liquor

the

that

of

Maximum

storm

season

(mg/l)

Mean

temperature,

during

minimum

Grove

(ref.7)

concentration

increasing

the

Clifton

1977

condition The

and

on

June

of

and

mean

attributed from

Generally,

offer

the

pots to

liquor's

oxygen

maximum

atures,

the

with

dissolved

temperature

about

5 &

activity.

liquor

closely

sun

of

bacterial decreases

recharge

gully

indicator

gully

for daily

the

liquor gully

adequate

gully

liquors

(as

condition, catchment

runoff

but areas

volume

in

Tables

they

may

necessary, to

effect

in a

221 measure

of mean

97,

oxygen liquor

impermeable ijo

=

For DO

28A,

Grove,

34,

period

52

about

and

84

high

summer

and

of

dissolved in

ships

the

between previously

SEDIMENT

TRANSFER of

(gullies with

1

FROM

35,

less

the

concentration 35

initial

for sample

concentration suspended

was the

to

150 and

the

an

development on

liquor,

quality

and

suspended of

human

the

relationhave

SEWER

been

Tables

7

than

suspended

solids

the storm

would at .(ref.lO).

35

-

suggest source, The

"first

periods

18%

of

in

initial on

the

44%

flush"

1980 sample

mean there

e.g.

October final

observation

the

value

28th

165mg/l, that

an

total

concentration

77mg/l,

range

the

mean and

and

concentration

83mg/l,

summarise

only

concentration,

a

to

research in

higher

Reinertsen

8

sediment

during

events, the

surface

discharges,

actually

by

and

different

suspended

This

runoff

pollutants

roof from

locations

assess

liquor

obtained

of.sediments

three

32 to

samples

26mg/l.

at

during

gully

sample's

mean

SYSTEM

minutes,

surface/gully,

final

initial

95mg/l,

made

than if as

gully

obtained

Grove

10

pot

the

was 24

exhaustion been

Clifton

road

TO

were

unfortunately,

solids

obvious

CATCHMENT

surface/gully

half

gully

500m*

order,

characteristics

quality.

for

road

final

to

larger

duration

the

liquor

in

up

residential

period

catchment

surface

discharge

events than

on

road

discharges,

For

and

from

parameters

catchment

on

a

catchmean

considered

of

dry

discharges

46)

the

catchment

catchment

stage

in

GULLY

pot

duration of

quality

BOD

being

DO

(ref.1).

C 2,

contribution total

and

gully

sampling

design

antecedent

concentrations

COD

reported

Samples

is

summer mean

gully upon

considerably

quality

a the

areas

seem

6,

catchments

based

suggested

liquor

catchment

during raise

required

level,

(ref.9)

gullies

gully

the

DO

catchments

gully

15'C,

Mean

which in

To

of

mean

185m*.

(Eq.8),

impermeable

(ref.l),

the

is

4.2mg/l

of

recommendation

the

solids

activity

same

at

influence

and

the

(8) area

concentration

require

Certainly,

criterion

The

86

to

0.99)

potential.

totals

gully

be

estimate

this

=

temperature

would

design of

important

liquor

raintall

maintenance

to

observed

pollutants

achieve

200m*

53,

related

catchment

estimated mean

a

6mg/l

necessary.

present

43,

be

(r

gully

A previous

to weekly

were

at

(Eq.8).

area

be the

liqour to

300m2

ment

mg/l average

would

with

gullies

could

1.5

the

to

concentration

also

t

concentration

For

concentration

areas:

IMPAREA

Clifton

generally. DO

catchment

0.015

corresponds

of

recharge

gully

volatile

was

no which

and

has

222 TABLE

7

Mean

concentraLions

in

and

in

fallout

-

October

pollutant

discharges August

1979

atmospher-ic 1980

Constituent

Suspended

solids

Dissolved

pal.

Clifton

and

Grove,

r\Lmospheric raIlout

(mg/l)

(ms/l)

96.6 (7 -

12.3 (1 -

249 (36

608)

-

113.5 (4 -

roof

Nottingham

Roof surface discharge

COD

TABLE

for

(ref.8)

157.5 (16 -

solids

surface/gully

Road surCace /gully pot discharge (ms/l)

solids

Total

road

1986)

202 (78

2070)

216 (88

-

57.9 (8 -

615)

24.0 (6 -

83)

72)

740)

71.4 (20

-

243)

762)

97.3 (21

-

268)

43.5 (5 -

360)

1SO)

8

Mean

pollutant

Grove,

concenLrations

Nottingham,

Constituent

Suspended Volatile solids Dissolved DOD COD

solids suspended

"exhaustion

of may

the

relative

1977

total -

for

Number samples

94.5

852

257

60 492 44.5 600

22 183 125 147

apparent

and

as

in

total

functions

quantities

catchment

runoff

of

discharge

in-pipe

of

of

Clifton

(ref.7)

Maximum (ms/l)

explained

times

discharge

1977

Mean (ms/l)

sediments" be

catch

June

26.8 119 8.7 63.4

solids

monitoring

in

August

deposition

from

road

and

and

roof

surfaces. A storm Grove at

runoff

catchment the

their

due

earlier recession surfaces

relative

and to

Whilst

that

model

(ref.5)

outfall

catchment.

case

simulation

each

and storm

magnitudes roof

and

runoff higher

limb. via

peak

gully

to to

and

pots

for the

and

iE

suspended

is

not

is

exhausted

across

hydrographs

differ,

it

surface

Clifton hydrograph

runoffs

different

road

the

component

surface

timings

discharges

developed

predict roof

produces

preceeds

Therefore, the

used

road

was

is

runoff, first

during

generally

the

contributes to

sediment

the and

cease input a

the in

from storm

the road event;

223 roof

surface-originating

erably

I.over

“first

Ii ush”

the

suspended

than

those

from

effects

occur

high

initial,

discharges

seem

deposits,

originating

suspended

likely

to

concentrations

surfaces

(see

during

predominantly

solids

concentrations

be

on

solids

road

the

the

result

recession

are

‘Table

7);

roof-only

runofr,

in

of’

the

limb

of

the

outfall

flushing a

consid-

and

of

pipe

previous

storm

event. Mean at

observed

the

Table

from

concentrations

the

Clifton

in

Grove

stormwater

catchment

discharges

are

given

in

8.

Factors

influencing

The

effect

in

sewers

(ref

parameters analysis, pot

sediment

dominating

discharged,

.l’Z)

may catchment

using

a

duration

of

which

are

For

most of

COD

and

individual

the

solids,

-

factors concentration

0.0%

3% with

supports the

the

conclusion

surface

sediment

period

of the

the

from

of

the

mobilis-

available

for

the

event.

antecedent 90%

peak

Only and

runoff

the 15

major

variance.

the

the

surtace/gully

solids

affecting

not before

road

the

This

factors

storm

parameters,

exhausted is

in

regression

three

slope

period.

explaining

gully

of

important,

dissolved

the

catchment

it

flows

meteorological

suspended

necessarily

sediments

importance,

other

were

90%

that

volume

of

intensity

mean

dry

not

on

intensity,

with

are

accummulation

greater

mean

total

Multiple

rainfall

explaining

suggesting

of

events

that

antecedent

sediments

ation

19

associated the

or loading

influence

flow-weighted,

event, was

rainfall, pollutant

characteristics.

and

the runoff

that

the

indicated

variance

total the

from

5-minute

h i g h !r’ a y ,

of

mask

data

catchments

1-mi.nute,

transfer

determining

and

influencing of

pollutant

outfall

of

dry the

period

was

variance

for

of

the

catchments.

CONCLUSIONS A summary and

of

stormwater middle-income,

between

August

pots

within and

been

examined.

from

a

detailed

research

runof

typical

devices

field

E quality

1976

and

the

storm

as

sources

area of

area

October

1980.

drainage

Orders

pollutant

concerning have

aspects,

residential

residential study

findings,

‘The

system,

as

of

sediments

and

of

magnitude

of

have

been discharges

in

sediment

been the

U.K.,

reported

of

interceptors,

such

the

the

a

gully

retention pollutants

pollutants and

from

for

monitored

performance

associated some

supply

presented

has

discharged need catchments

for

further is

224 In

recommended. represent

a

associated in and

some in

very highway

constituent commercial

total

area

significant pollutants concentrations

across source

the ol

U.K.,

discharge,

the CO

residential

stormwater

those

catchments runoff

latter monitored

and

being on

similar motorways

areas.

REFERENCES 1

2

3

4

5

6

7

8 9

10

11 12

I.J. Fletcher, C.J. Pratt and G.E.P. Elliott, An assessment of the importance of roadside gully pots in determining the quality of stormwater runoff, in P.R. Hellivell (Ed.), Urban Storm Pentech Press, London, 1978, pp. 586-602. Drainage, Mathematical simulation of pollutI.J. Fletcher and C.J. Pratt, ant contributions to urban runoff from roadside gully pots, in Yen (Ed.), Stormwater Quality, Management and Planning, B.C. Water Resources Publications, Littleton, U.S.:\., 1982, pp.116-124 Sediment washoff into roadside C.J. Pratt and J.R.W. Adams, gullies, in B.C. Yen (Ed.), Stormwater Quality, Management and Planning, 1v'ater Resources Publications, Littleton, U.S.A., 1982, 174-183. K . Pratt and R.J. Henderson, Overland flow and catchment characteristics, in B.C. Yen (Ed.), Urban Stormwater Hydraulics Water Resources Publications, Littleton, U.S.A., and Hydrology, 1982, pp. 83-92. Pratt and J.J. Harrison, Storm runoff simulation on a C.J. calibrated catchment, in R.E. Featherstone and A. James (Eds.), Urban Drainage Systems, Pitman, London, 1982, pp. 2-143 - 2-155. J.B. Ellis, The nature and sources of urban sediments and their relation to water quality, in G.E. Hollis (Ed.), Mans Impact on the Hydrological Cycle in the U.K., Geo Abstracts, Norwich, 1979, 199-210. T"; . Fletcher, Quality of urban stormwater runoff: an appraisal of the role of gully poy liquors, Unpublished PhD Thesis, Trent Polytechnic, Nottingham, 1981. J.R.W. Adams, Contaminants in urban stormwater, Unpublished PhD Thesis, Trent Polytechnic, Nottingham, 1983. Anon., Guide to the requirements for the design of highways and paved areas in residential and industrial development, Nottinghamshire County Council, Dept. of Planning and Transportation, Nottingham, 1978. T.R. Reinertsen, Quality of stormwater runoff from streets, in B.C. Yen (Ed.), Urban Stormwater Quality, Management and Planning Water Resources Publications, Littleton, U.S.A., 1982, pp. 107115. M.C. Wilson and C.J. Pratt, Unpublished laboratory results, Trent Polytechnic, Nottingham, 1979-1982. G. Mance and M.M.I. Harman, The quality of urban stormwater runoff, in P.R. Hellivell (Ed.), Urban Storm Drainage, Pentech London, Press, 1978, pp. 603-617.