Understanding the discoloration risk as consequence of hydraulic transients

Agostinho, Mariele de Souza Parra; Fernandes, Cristovão Vicente Scapulatempo

doi:10.1590/2318-0331.292420240011

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Scientific/Technical Article • RBRH 29 • 2024 • https://doi.org/10.1590/2318-0331.292420240011 copy

Understanding the discoloration risk as consequence of hydraulic transients

Entendendo o risco de descoloração como consequência de transientes hidráulicos

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This paper presents an analysis of the challenges associated with discoloration risk management and the impact of hydraulic transients on water quality within distribution systems. Focusing on the Metropolitan Region of Curitiba, Paraná, Brazil, the study employs a comprehensive methodology that combines the Characteristic Method for simulating hydraulic transients and real-time monitoring of water quality parameters, such as turbidity and chlorine levels. A framework for managing discoloration risk is proposed, highlighting strategies for identifying potential causes, assessing risk severity, developing prevention and mitigation strategies, and implementing continuous improvement processes. The experimental section details the impact of hydraulic transient events on water quality, with significant findings indicating a direct correlation between flow dynamics and water quality degradation, particularly in terms of increased turbidity and decreased chlorine levels during pump deactivation. The study contributes valuable insights into effective water distribution system management, emphasizing the importance of advanced monitoring and risk management techniques to maintain high-quality water standards.

Keywords:
Real system; Hydraulic transient; Discoloration; Drinking water; Risk management

CAMPAIGN	PROCEDURE	CONDITIONS
1ª	Operational Procedure: Start – Shut down	10 minutes between starts.
1ª	Operational Procedure: Start – Shut down	Start: pump OFF
2ª	Shut down – Start – Shut down – Start	4 minutes between starts.
2ª	Shut down – Start – Shut down – Start	Start: pump ON
3ª	Shut down – Start – Shut down	4 minutes between starts.
3ª	Shut down – Start – Shut down	Start: pump ON
4ª	Shut down – Start – Shut down	4 minutes between starts.
4ª	Shut down – Start – Shut down	Start: pump ON

a					b
Risk	Index	Author	Code	Definitions of variables	Case study
Risk assessment associated with negative pressure	Intrusion potential	Friedman et al. (2004)Friedman, M. L., Radder, S., Harrison, D., Howie, M., Britton, G., Boyd, H., Wang, R., Gullick, M., LeChevallier, D., Wood, D., & Funk, J. (2004). Verification and control of low pressure transients in distribution systems. Denver: American Water Works Association.	C1	Number of junctions with pressure < 0 mH2O	92
	Intrusion potential	Friedman et al. (2004)Friedman, M. L., Radder, S., Harrison, D., Howie, M., Britton, G., Boyd, H., Wang, R., Gullick, M., LeChevallier, D., Wood, D., & Funk, J. (2004). Verification and control of low pressure transients in distribution systems. Denver: American Water Works Association. adapted	C2	% of junctions with pres.< 0 mH2O	97.9%
	Cavitation		C3	Number of junctions with vacuum pressure	85
	Cavitation		C4	Total time cavitation	69s
	Severity of cavity index	Martin (1983)Martin, C. S. (1983). Experimental investigation of column separation with rapid closure of downstream valve. In Proceedings of the 4th International Conference on Pressure Surges. Bath: British Hydromechanics Research Association (BHRA).	C5	$S = \frac{T_{S C} a}{2 L}$	9.3
	Severity of cavity index		C5	S=severity of cavity index; a=celerity; TSC=duration when cavity occurs; L=length	9.3
	Surge Damage potential factor (SPDF)	Jung & Karney (2011)Jung, B., & Karney, B. (2011). Pressure surge analysis of pumping stations for water distribution systems. Journal of Hydraulic Engineering, 137(2), 175-182. adapted.	C6	$S P D F^{- =} \frac{\int_{i e N_{n o d e}} H_{i} d t}{junctions}$	-443.08
			C6	Hi = pressure < Hmin (allowable pressure)	-443.08
Risk assessment associated with positive pressure			C7	$S P D F^{+} = \frac{\int_{i e N_{node}} H_{i} d t}{junctions}$	2.88
Risk assessment associated with positive pressure			C7	Hi = pressure > Hmax (allowable pressure)	2.88
Risk assessment associated with negative and positive pressure			C8	$S P D F = \frac{\int_{i e N_{node}} H_{i} d t}{junctions}$	-440.19
			C8	Hi > Hmax or <Hmin	-440.19
	Δ pressure	Jung & Karney (2006)Jung, B., & Karney, B. (2006). Hydraulic transient guidelines for protecting water distribution systems. Journal of Water Management Modeling, R246-09. adapted	C9	ΔP = Hmax - Hmin	281
	Hmax		C10	Minimum Pressure	-10
	Hmin		C11	Maximum Pressure	271
	Positive and negative transient risk index	Radulj (2009)Radulj, D. (2009). Assessing the hydraulic transient performance of water and wastewater systems using field and numerical modeling data. (Master’s thesis). University of Toronto, Toronto. adapted	C12	$T R I^{+} = \frac{\int_{0} T^{+ P_{\max} d t}}{junctions}$	99.82
	Positive and negative transient risk index		C13	$T R I^{-} = \frac{\int_{0} T^{- P_{\max} d t}}{junctions}$	-9.52
Risk assessment associated with rapid change of pressure	Damage index	Shinozuka & Dong (2005)Shinozuka, M., & Dong, X. (2005). Monitoring and management of water supply systems. In 4th Korea Infrastructure Safety and Technology Corporation (KISTEC) International Seminar on Safety of Infrastructures. Jakarta: KISTEC.	C14	$D = \frac{H_{2} - H_{1}}{t_{2} - t_{1}}$	-86.8
Risk assessment associated with rapid change of pressure	Damage index		C14	D = damage index; H2 and H1 = pressure heads at a node at time t1 and t2, respectively	-86.8

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