Pollution in storm water runoff. Two cases: an urban catchment and

Pollution in storm water runoff.
Two cases: an urban catchment and a highway toll
gate area.
Qualité des eaux pluviales en réseau d’assainissement.
Le cas d’un bassin urbain et celui d’une station de péage autoroutière.
O. J. Barco, C. Ciaponi , S. Papiri
Department of Hydraulic and Environmental Engineering,
Università degli Studi di Pavia, Via Ferrata, 1, 27100 Pavia, Italy.
Tel (+39) 382 505764, Fax (+39) 382 505589.
RÉSUMÉ
Dans cette étude sont présentés les résultats d’un programme de suivi de la qualité
et de la quantité d’eau pluviale d’un basin urbain expérimental situé à Pavia (Italie).
Une nouvelle installation expérimentale située sur une station de péage autoroutière
à Cremona (Italie) est également décrite.
Les données des evenements pluvieux et les paramètres qualitatifs des eaux de
ruissellement pluviales ont été recueillis à partir de juin 2000. La conductivité
spécifique, le DCO, le DBO5, les concentrations en solides décantables, en azote
total, en azote ammoniacal, en phosphore, en plomb et en hydrocarbures ont été
analysées au laboratoire.
Ces données ont été utilisées pour calibrer les paramètres du modèle SWMM afin de
simuler les diagrammes de masse observés.
ABSTRACT
This paper describes the results of a monitoring program regarding storm water
quantity and quality of an experimental urban catchment situated in Pavia (Italy) and
describes the new experimental site in a highway toll gate area in Cremona (Italy).
The rainfall-runoff data and quality parameters have been collected since June 2000.
In the laboratory, analyses of specific conductivity, COD, BOD5, suspended solids,
settleable solids, total nitrogen, ammonium nitrogen, phosphorus, lead, zinc and
hydrocarbons, are carried out.
This data has been used to calibrate the parameters of the SWMM model in order to
simulate observed loadographs.
KEYWORDS
experimental urban catchment, storm water, water quality, monitoring, highway toll
gate area.
NOVATECH'2004
1
1. INTRODUCTION
The characterization of contaminants in storm water runoff in the impervious areas is
a complex problem that has become an increasingly important environmental issue
for urban communities. Several studies, often based on quite thorough monitoring
campaigns, have been carried out from the beginning of the 1970's (USEPA, 1983;
Novotny et al.,1985 ; Bujon and Herremans,1990 ; Saget et al.,1998; Legret and
Pagotto, 1999) to assess the fluxes of pollution going through separate and combined
sewer networks and to quantify the impact of urban wet weather discharges in the
receiving water.
In Italy, since 1980 some experimental urban catchments have been equipped for
runoff quantity monitoring studies, and later for some of these, the investigation has
been extended also to quality data (Artina et al., 1997; Milano et al., 2002; Ciaponi et
al., 2002).
This paper presents the results of a monitoring program regarding storm water
quantity and quality during a 3 year period (2000-2003) at the Cascina Scala,
experimental urban catchment site. It presents some of the results found during the
simulation of the observed hydrograph and loadographs using the SWMM model and
describes a new experimental site in a highway toll gate area in Cremona (Italy).
2. THE EXPERIMENTAL CATCHMENT AT CASCINA SCALA (PAVIA)
The Cascina Scala experimental urban catchment has been functioning since 1989.
It is an urban district located in the northern part of Pavia (Lombardia-Italy). The total
contribution area adds up to 126,780 m2, where 62% of the total area is impervious
(22.7% roofs and 39.6% streets and paved surfaces), while 38% of the total area is
pervious. The combined sewer network has a total length of 2,045 m; the slope of the
sewer pipes ranges between 0.15% and 1.01%. All the sewers are made of standard
concrete pipes.
Cascina Scala is an urban catchment of exclusively residential use. The population is
around 1,500 inhabitants.
More details on the physical characteristics of the basin and the drainage system are
reported in another paper (Ciaponi and Papiri, 1994.)
The rainfall on the basin is being measured with two tipping bucket rain gauges with a
0.2 mm accuracy. The distance between the two rain gauges is 310 m, therefore the
spatial uniformity of the precipitation can be checked and the meteorological volume
can be evaluated accurately. Storm water runoff in the final reach of the sewer
network is measured using a venturi tube with a bubbler flow meter. Temperature and
conductivity in the final reach of the sewer network are measured on site with a
multiparameter sonde. Storm water runoff samples are being collected by a
refrigerated automatic grab sampler equipped with 24 bottles. In the laboratory
analyses of specific conductivity, COD, BOD5, suspended solids, settleable solids,
total nitrogen, ammonium nitrogen, phosphorus, lead, zinc and hydrocarbons, are
carried out.
3. THE EXPERIMENTAL CATCHMENT OF CREMONA
The experimental site is located in northern Italy at a toll gate area in Cremona in the
Brescia-Piacenza highway (A21). The total contributing area adds up to 2560 m2,
where 86.5 % of the total area is impervious (53.4 % in asphalt surfaces, 18.1 %
covered area and 15 % parking area in asphalt) while 13.5 % of the total area is
pervious (green space).
2
NOVATECH'2004
The sewer network has a total length of 198 m; the sewer pipes have diameters of
200 and 300 mm.
The runoff drains to an oil separator and after drains in the ditch.
The purpose of the experimental site is to acquire data of water runoff quality in a
high vehicular traffic area and to verify the performance of a stormwater pollution
control commercial system (EcoDrainTM) which is generally installed in storm drains
(Papiri et al., 2002).
The runoff of the sampling system is withdrawn upstream of an oil separator by
means of the first distributing device. This device divides the runoff water (Q) into two
flows: 20% of the runoff (Q1) is collected for the sampling system, the other 80% (Q2)
continuous to the oil separator which is of no concern to the experimental. Q1 reaches
a second distributing device that divides the flow into equal parts, the first one (Q3) is
carried to a tank and the second one (Q4) is carried to the EcoDrainTM. In the
EcoDrainTM system the arriving flow is divides into two runoff flows, represented by Qf
and Qnf : Qf is the flow which passes through Aikaterisil pillows (which should be
capable of absorbing the pollutants carried in the water), while Qnf is the flow which
by-passes the filtering system. After passing through the EcoDrainTM system the two
flows (Qf and Qnf) are held in two differents tanks (figures 2 and 3).
For the meteorological events, samples from every tank (Q3,Qf and Qnf), will be
collected and analysed in order to estimate the qualitative median characteristics of
the runoff, both the filtered runoff and the anfiltered nunoff.
With the known volume of the water into the tanks it is possible to control the total
mass and therefore the actual efficiency of the EcoDrainTM.
4. MEASUREMENT AT THE CASCINA SCALA EXPERIMENTAL
URBAN CATCHMENT.
The rainfall-runoff data has been collected from June 2000 with some interrupted
periods to due problems with instrumentation. The data collection refers to 21
meteorological events during which 254 samples were collected and analysed.
Presently, experimental data acquisition is going on.
Table 1 presents the main characteristics of rainfall, runoff, and water quality
observed during each of the 21 events, i.e. rain depth, runoff volume, collected
samples, dry days, mass (SS and BOD5), event mean concentration (EMC) and the
range of concentrations of SS e BOD5.
In the case when samplings adequately cover the whole experimental hydrograph,
the calculations of event mean concentration (EMC) are possible and those events
was selected to study.
For the event N°20 (31/07/03), a particular analysis in the laboratory was done:
referring to the first 6 samples (first part of the event), analization was done for the
content of COD, BOD5, phosphorus, lead and zinc in both liquid and solid parts
(suspended solids), while for the remaining samples analization was done only the
liquid part, because the solid part was negligible. The results in Table 2 shows that
the COD and BOD5 concentrations are very high, more noticeable than during dry
weather (Ciaponi et al, 2002). Also, the table shows that a remarkable fraction of the
load connected with the carbonic substances is associated with the solid part. The
fraction of heavy metals associated with the solid part (100% for lead and >50% for
zinc) is also extremly high.
NOVATECH'2004
3
5. MODEL CALIBRATION
The quantity and quality simulation of urban runoff has been performed with the
model SWMM (Storm Water Management Model), and the parameters of the model
have been calibrated using field data.
The application of the SWMM model has given good results with regards to the
simulation of runoff quantity and quality. The quality simulation has shown,
furthermore, that the final results depend strongly on the parameters which influence
the buildup and the washoff of the pollutants. For example, in Figure 4 the
experimental data (hydrographs associated with hyetographs and loadographs) and
the corresponding simulated hydrographs and loadographs are reported for two
events. Table 3 shows the values adopted in the SWMM calibration of the buildup
and washoff processes, according to the values proposed in literature (Huber and
Dickinson,1988).
6. CONCLUSION
The observed data confirms the importance of wet weather discharged pollution,
already shown by worldwide studies published previously.
The application of the SWMM model has demostrated satisfactory results with
regards to the simulation of runoff quantity and quality. The quality simulation shows,
furthermore, that the final results depend strongly on the parameters which influence
the buildup and the washoff of the pollutants.
The results of Table 2 (analysis liquid and solid part) shows, for some parameters, a
remarkable fraction associated with the solid part. This is an interesting point, but is
only for one event. The experimental data acquisition is expected to proceed in order
to confirm this results through greater number of observed events.
LIST OF REFERENCES
Artina S., Maglionico M., Marinelli A. (1997). Le misure di qualità nel bacino urbano Fossolo.
Modelli quali-quantitativi del drenaggio urbano, p. 21-78, Centro Studi Deflussi Urbani, Milan.
Bujon G., Herremans L. (1990). FLUPOL Modèle de prévision des débits et des flux polluants en
réseaux d’assainissement par temps de pluie: calage et validation. La Houille Blanche, n. 2.
Ciaponi C., Papiri S. (1994). Bacino di Cascina Scala - Codice IT04. Le misure di pioggia e di
portata nei bacini sperimentali urbani in Italia, p. 1-127, Centro Studi Deflussi Urbani, Milan.
Ciaponi C., Mutti M. e Papiri S. (2002). Storm Water Quality in the Cascina Scala (Pavia Italy)
Experimental Catchment. New Trends in Water and Environmental Engineering. June 24-28.
Capri (Italy).
Huber W.C., Dickinson R.E. (1988), Storm Water Management Model: User’s Manual. EPA
Athens, Georgia.
Legret M., Pagotto C. (1999). Evaluation of pollutant loadings in the runoff waters from a major
rural highway. The Science of the total Environment , 235, pp 143-150.
Novotny V., Sung H.M., Bannerman R., Baum K. (1985). Estimating nonpoint pollution from small
urban watersheds. Journal of Water Pollution Control Federation, vol. 57.
Papiri S., Ciaponi C., Capodaglio A., Collivignarelli C., Bertanza G., Swartling F., Crow M.,
Fantozzi M., Valcher P. (2002). Field Monitoring And Evaluation Of Innovative Solutions For
Cleaning Storm Water Runoff.- “IWA, World Water Congress”, Melbourne, Australia, April, 712.
Saget A., Gromaire-Mertz M. C., Deutsch J.C., Chebbo G. (1998). Extent of pollution in urban
wet weather discharges. Atti della conferenza internazionale “Hydrology in a Changing
Environment”. Luglio 6-10. Exceter, UK.
Milano V., Plagliara S., Dellacasa F. (2002). Urban Stormwater quantity and quality in the
experimental urban catchment of Picchianti. New Trends in Water and Environmental
Engineering. June 24-28. Capri (Italy).
USEPA (1983). Results of the Nationwide Urban Runoff Program: Volume 1 – Final Report.
United States Environmental Protection Agency, Springfield, Virginia 22161.
4
NOVATECH'2004
Figure 1: Map of the Cascina Scala experimental catchment.
Figure 2: Map of the Cremona experimental catchment
discharge-pipe
3
Tank: Vol. 2 m
Lifting manhole
water discharge flume
Cut off valve
3
Tank: Vol. 1,2 m
Diameter 110 mm
discharge-pipe
Q1
Distributing device No. 2.
Qf
Diameter 110 mm
Q4
Diameter 4 mm
Q3
Qnf
Ecodrain system
Tank: Vol. 1,2 m3
Figure 3: Distributing device system in Cremona experimental site
NOVATECH'2004
5
No. event
Date
Rain depth Runoff volume
[mm]
[m3]
Collected Samples Dray days
Mass [kg]
EMC [mg/l]
Range of concentrations [mg/l]
SS
BOD5
SS
BOD5
SS
BOD5
3 11/06/00
11,8
452
3
0,5
-
-
-
-
40-160
4 13/06/00
2,0
28
1
0,8
-
-
-
-
270
247
5 23/06/00
16,4
764
18
10,8
288,7
129,4
163
80-890
29-765
6 28/06/00
15,6
752
12
4,8
-
-
-
280-1360
70-400
7 08/07/00
7,0
232
8
3,3
351,9
78,3
1430
318
800-2960
160-550
54
40-1000
18-380
364
242
8-105
8 10/07/00
11,0
438
12
1,8
118,0
26,3
9 11/07/00
10,6
466
4
0,9
-
-
-
-
40-180
55-120
10 13/03/01
3,8
131
12
0,3
-
-
-
-
50-840
50-600
11 17/03/01
26,2
1416
24
3,9
165,9
98,4
108
64
20-1280
24-880
12 28/03/01
18,6
935
24
11,0
126,3*
108,4*
120*
103*
80-2360
64-1780
13 10/04/01
8,4
444
16
3,3
201,3
117,0
420
244
120-1420
55-900
14 20/04/01
15,8
861
22
0,0
366,5
197,3
377
203
50-1190
23-2120
615
180-2430
320-1300
450-1000
220-720
15 02/03/03
4,8
164
7
0,6
151,6
124,7
16 09/04/03
18,0
492
5
5,7
-
-
748
17 11/04/03
23,4
766
19
1,2
197.9
69,5
195
69
20-1400
28-500
18 28/06/03
38,8
2600**
20
29,9
995.3
488.2
378
185
70-1605
70-1000
-
-
19 24/07/03
12,6
485
12
25,9
247,0
97,9
442
175
116-1770
85-700
20 31/07/03
16,20
775
20
6,8
180,4
91,2
213
108
36- 1470
34- 850
21 24/09/03
8,6
224
9
14,2
126,0
61,0
365
177
198-3880
115-720
Table 1 : Water quality parameters for observed storm events
(-) Samples temporal distribution does not correct evaluation of EMC values. * Value affected from uncertainty for unavailability of samplers in the second part
of the hydrograph. ** The sewer reaches pressure flow conditions. For space reasons, alone 19/21 events are presented.
6
NOVATECH'2004
E v e nt 1 1 ( 1 7 / 0 3 / 0 1 )
500
0.2
400
0.4
300
SWM M simulatio n
* Experimental data
200
0.6
6
5
Mass Rate [kg/min]
0
Rainfall Intensity
[mm/min]
Flow Rate [l/s]
E v e nt 1 1 ( 1 7 / 0 3 / 0 1 )
600
0.8
100
0
0
100
200
300
400
500
4
3
*
1
0
1
600
0
100
200
E v e nt 1 9 ( 2 4 / 0 7 / 0 3 )
0
SWM M simulatio n
* Experimental data
0.012
200
0.018
100
0
150
200
250
300
350
0.024
400
Mass Rate [kg/min]
Flow Rate [l/s]
0.006
400
100
10
600
SS (SWM M simulatio n)
* SS (Experimental data)
5
0
0
100
Time [min]
200
Time [min]
Figure 4 : Quantity and quality simulations for the events 11 (17/03/01) and 19 (24/07/03)
NOVATECH'2004
500
15
Rainfall Intensity [mm/min]
500
50
400
E v e nt 1 9 ( 2 4 / 0 7 / 0 3 )
600
0
300
Time [min]
Time [min]
300
SS (SWMM simulation)
SS (Experimental data)
2
7
300
400
Parameters
Liquid part
Samples concentration
unseparated [mg/l]
concentration [mg/l]
Solid part
%
concentration [mg/l]
%
Samplers 1-2*
COD
1720
575
33
1145
67
BOD5
850
270
32
580
68
Phosphorus 11,36
4,55
40
6,81
60
Lead
0,125
<0,01
0
0,125
100
Zinc
0,678
0,10
15
0,578
85
COD
1101
417
38
684
62
BOD5
550
190
35
360
65
Phosphorus 7,46
2,44
33
5,02
67
Lead
0,118
<0,01
0
0,118
100
Zinc
1,05
0,48
46
0,57
54
COD
741
337
45
404
55
BOD5
370
160
43
210
57
Phosphorus 3,96
1,71
43
2,25
57
Lead
0,088
<0,01
0
0,088
100
Zinc
0,40
0,02
5
0,38
95
Samplers 3-4*
Samplers 5-6*
•
Because of analysis exigency, samples have been coupled.
Table 2: Dissolved and adhered pollutants in the first fraction of the event N° 20.
Parameter
Value
Surface buildup factor [Kg/haimp/day]
18
Buildup decay factor [1/day]
0.3
Washoff coefficient [1/mm]
0.13
WASHPO
1.2
Table 3 : Parameter values adopted in SWMM calibration.
ACKNOWLEDGEMENTS
This research has been financed by MIUR 2002 and Premio Provinciambiente 2001, granted to
Milan province.
Special thanks are given to Paola Boriani for her contribution to this research while working on
her thesis.
8
NOVATECH'2004

Download Report