Proposed Appropriate Best Management Practices for Quality and Quantity Control of Highway Runoff in Amman

Transcription

1 Proposed Appropriate Best Management Practices for Quality and Quantity Control of Highway Runoff in Amman Zain M. AL-Houri, Abbas Al-Omari & Hazem Shakaa Assistant Professor: Civil Engineering Department Applied Science University EXCEED REGIONAL WORKSHOP - ANTALYA Session I: Urban Water Management 17 May 2014, Antalya, Turkey

2 OUTLINE Introduction Objectives Approaches Results and Discussion Conclusion Recommendations and Future Needs

3 Introduction Urbanization & New Developments Reduced Infiltration & Increased stormwater runoff in Conventional Drainage Systems Quality & Quantity Concerns

4 Introduction Quantity Concerns Flooding when the drainage system cannot cope with the large volumes of water entering it or if it is blocked. Sewer overflows containing foul waste which create a range of additional problems to streams or treatment works.

5 Introduction Quality Concerns Runoff will collect more pollutants which may threaten our groundwater and receiving waters. These pollutants are a cocktail of oils, sediments, herbicides, pesticides, road debris and particulates from the breakdown of the pavement themselves

6 INTRODUCTION Best Management Practices (BMPs) are designed to provide a means of avoiding or mitigating these negative impacts. BMPs are designed to serve the dual purpose of: Runoff Quantity Control Runoff Quality Control

7 OBJECTIVES In recognition of the importance of stormwater management in the highway environment, this study is conducted to provide recommendations for appropriate types of BMPs that can be implemented to mitigate the problems in the way that existing drainage systems handle the quantity and quality of stormwater runoff.

8 STUDY AREA Two sites in the vicinity of Amman, Jordan were chosen for this investigation: Site1 located in Yajouz Street & Site 2 located in Shafa Badran Street. These sites chosen based on: Topography Soil characteristics, Environmental factors such as noise and air pollution Average Daily Traffic (ADT).

9

10 Site 2: Shafa Badran Street

11 Approaches To successfully select and recommend the appropriate BMPs which can be incorporated in highway stormwater management in Amman, the following approaches have been used: Evaluate the runoff volumes generated at the sites. Identify the sources and factors affecting the quality of runoff in the highway environment. Review the available User s Guide, and BMPs Design Manual to select a particular BMP facility for the sites

12 Approach I Quantifying Highway Runoff Volume

13 Calculated Runoff SCS-CN Method Required Input to SCS-CN method Q ( P P I 2 Ia ) S Rainfall Depth a S CCN Ia = 0.2 S Contribution Area CN Land use/land cover A* CN CN and Ia A

14 Rainfall Data Collection Rainfall data was collected using: Designed rain gages constructed at the workshop at Applied Science Private University. Rainfall data from JU weather station

15 Rainfall depth measured by the designed rain gag vs. measured rainfall by JU weather station: Site 1

16 . Rainfall depth measured by the designed rain gag vs. measured rainfall by JU weather station: Site 2

17 Watershed Delineation: Arc-GIS Hydrologic Tool DEM Contour Maps Flow Direction Watershed Delineation

18 DEM Site 1 Site2

19 Site 1 Contour Maps Site 2

20 Site 1 Watersheds Site2

21 Site 1

22 Site 2

23 Land use Maps: GIS tool Site 1 Site 2

24 Summary of the SCS-CN method for sites 1 and 2 Land Use Area (km 2 ) CN Site 1 Site 2 Agriculture Build Up Paved ΣArea = 0.93 ΣArea = 3.30

25 . Runoff Depth: Site 1

26 . Runoff Depth: Site 2

27 Approach II Quality of Highway Runoff

28 Measured Runoff Runoff rates in each site were monitored by collecting the runoff volume in the culvert for a specific time and measured the time required to fill a certain volume of runoff.

29 Site 1 Measure Runoff- Locations Site2

30 Measured Runoff Flow Runoff Rate Flow Rate (LPM) Site 1 Site 2 Minimum Flow Rate Maximum Flow Rate

31 Main Factors Affecting Runoff Quality Rainfall intensity Average daily Traffic (ADT) Antecedent dry period (ADP) defined as the dry period between two consecutive rainfall events.

32 Average Daily Traffic (ADT) Measurement ADT in both sites is measured by counting the number of vehicles (Passenger cars and Trucks) in both directions during the period of 4:00 to 5:00 pm for site 1 and 2 Site No. ADT (Veh./Day) Trucks ADT (Veh./Day) Passenger Cars Total ADT (Veh./Day)

33 Runoff Quality The quality of each runoff sample was analyzed at Water, Energy and Environmental Center at Jordan University. The chemical analyses include: Total dissolved solids (TDS) Total suspended solids (TSS) PH & Selected heavy metals (Zn, Fe, Cd, Ni, Pb, Cr, Cu)

34 Correlation I: ADP- TDS- Rainfall Depth Site 1 Site 2 The highest TDS is at the first rainfall event which has the highest ADP The highest TDS was for the rainfall event that has an ADP of 4 days TDS at site 1 is higher than that at site 2 which is most probably due to the higher ADT volume at site 1

35 Correlation II: ADP-TSS-Rainfall Depth Site 1 Site 2 The highest TSS is at the first rainfall event which has the highest ADP The highest TSS is at the rainfall event which has ADP= 38days Strong correlation is observed between rainfall depth and TSS TSS was higher at site 1 than at site 2 which is most probably due to the higher ADT at site 1

36 Site 1 Correlation III: ADP-pH-Rainfall Depth Site 2 ph ranged between 7.1 and 7.7 at both sites. No significant variations in ph levels were observed at both sites. It is noted that a ph drop is observed at high rainfall depth which is most probably due to increasing CO2 levels in the rainwater.

37 Correlation IV: ADP- Heavy Metals - Rainfall Depth Of the heavy metals monitored Cd, Pb, Ni, Cr and Cu concentrations were all below the detection limit for all rainfall events for both sites, although ADT and rainfall depth are varied. However, Zinc (Zn) and Iron (Fe) were detected at both sites Metal Cd Ni Pb Cr Cu Zn Fe Detection Limit (mg/l)

38 Correlation V: ADP- Fe- Rainfall Depth Site 1 Site 2

39 Correlation VI: ADP- Zn- Rainfall Depth Site 1 Site 2

40 Approach III Incorporation of BMPs as Opposed to Existing Drainage Systems

41 Proposed BMPs for Highway Runoff Control Vegetated Grass Swale: Swales are broad, shallow channels designed to convey stormwater runoff and treat it by vegetative filtering and infiltration.

42 Proposed BMPs for Highway Runoff Control Vegetated Grass Swale:

43 Proposed BMPs for Highway Runoff Control Infiltration Trench: is an excavated trench lined with filter fabric and backfilled with stone. These systems encourage stormwater infiltration into subsurface soils and work well in space limited applications.

44 Proposed BMPs for Highway Runoff Control Infiltration Trench

45 Proposed BMPs for Highway Runoff Control Permeable Pavement is impermeable paver blocks that are installed with gaps between the pavers to allow stormwater to penetrate into the subsurface. Permeable pavements decrease runoff volume by allowing stormwater to infiltrate and improve water quality by filtering the stormwater through the aggregate subbase.

46 Permeable Pavements Proposed BMPs for Highway Runoff Control

47 Conclusions Water resources in Jordan are very limited which makes their protection from pollution an environmental priority. Promoting BMPs in Amman will bring a range of benefits: Quantity Control: BMPs reduce the quantity of water entering the drainage systems and therefore reduce surface flood risk, an important consideration in Amman, particularly given the increase occurrence of intense rainfall events as a result of climate change. Quality Control: BMPs improve the quality of runoff from development, brining clean water back into use.

48 Recommendations Such a study is a step forward to raise the awareness of local officials for the importance of incorporating BMPs, as opposed to the conventional drainage systems as new strategies in rainwater management in Amman. To successfully incorporates BMPs in highway stormwater management, a more comprehensive sampling program for a longer time period at several locations in the vicinity of Zarqa River is recommended to investigate the possible impact of highway runoff on Zarqa River quality.

49 Acknowledgment Applied Science University for funding this research. Akdeniz University in Antalya/Turkey and Technical University Braunschweig in Germany for organizing this workshop. The German Academic Exchange Services (DAAD) and Federal Ministry for Economic Cooperation and Development (BMZ) in Germany for the financial support of this activity.

50 THANKS