Optimization of multi-frequency electromagnetic surveying for investigating waste characteristics in an open dumpsite

Figures & data

Figure 1. Site description; (a) Location and aerial image map of the study area showing ERT profile locations and EMP-400 profiler measurement points, (b) Map of MSW disposal facility of the Nonthaburi provincial administrative organization, Khlong Khwang subdistrict, Sai Noi district, Nonthaburi province, Thailand, and (c) Images showing surface conditions of each profile.

Figure 2. The electrode positions for the Wenner–Schlumberger configuration of the ERT survey.

Table 1. Arrangement of the frequency set of FDEM surveys.

Type	Name	f (kHz)	Type	Name	f (kHz)
Low–High–High	A1	1,10,15	Low–Low–Moderate	G1	1,3,6
	A2	1,11,15		G2	1,3,7
	A3	1,12,15		G3	1,3,8
	A4	1,13,15		G4	1,3,9
	A5	1,14,15		G5	1,3,10
	E1	2,11,15	Low–Low–High	C1	1,2,15
	E2	3,11,15		C2	1,3,15
	E3	4,11,15		C3	1,4,15
	E4	5,11,15		C4	1,5,15
	I1	1,11,13	Low–Moderate–Moderate	H1	1,7,9
	I2	1,10,13		H2	2,7,9
	I3	1,12,13		H3	3,7,9
	I4	1,14,13		H4	4,7,9
	I5	1,10,11		H5	5,7,9
	I6	1,12,11	Moderate–Moderate–High	D1	6,7,15
	I7	1,14,11		D2	6,8,15
Low–Moderate–High	B1	1,6,15		D3	6,9,15
	B2	1,7,15		D4	6,10,15
	B3	1,8,15		J1	7,8,15
	B4	1,9,15		J2	7,9,15
	K1	1,7,10	Moderate–High–High	F1	7,10,15
	K2	1,7,11		F2	7,11,15
	K3	1,7,12		F3	7,12,15
	K4	1,7,13		F4	7,13,15
	K5	1,7,14		F5	7,14,15
	K6	1,7,15

Figure 3. Flowchart showing the selection process of an optimum frequency set.

Figure 4. Inverted ERT model for profiles (a) NTM-1, (b) NTM-2, and (c) NTM-3. Adapted with permission from “Applying electromagnetic surveys as pre-screening tools prior to open dump mining,” by Boonsakul et al. (2021), J mater cycles waste manag 23, 1518–1530. Copyright (2021) by Springer Japan KK, part of Springer nature.

Figure 5. (a) Inverted EM results of the EC model, and (b) synthetic ER models obtained by inversion modeling of the conductivity data acquired from FDEM measurement along profiles NTM-1, NTM-2, and NTM-3. Adapted with permission from “Applying electromagnetic surveys as pre-screening tools prior to open dump mining,” by Boonsakul et al. (2021), J mater cycles waste manag 23, 1518–1530. Copyright (2021) by Springer Japan KK, part of Springer nature.

Figure 6. Comparing the effective frequency sets of all profiles.

Figure 7. Distribution of ER data and synthetic ER data from (a) direct correlation analysis, (b) linear interpolation analysis, and (c) bilinear interpolation analysis.

Figure 8. Comparison of the R values of the effective frequency sets E4, I1, and K4 in all three profiles.

Table 2. Degree of RMSE value and the correlation (R) between the CS_HCP standard values and the average CS_HCP values for the effective frequency sets for each profile.

Profiles	RMSE	R
NTM-1 E4	4.50	0.54
NTM-1 I1	37.90	0.52
NTM-1 K4	33.70	0.52
NTM-2 E4	25.10	0.46
NTM-2 I1	24.40	0.33
NTM-2 K4	38.50	0.30
NTM-3 E4	9.50	0.99
NTM-3 I1	17.60	0.87
NTM-3 K4	25.00	0.89

Figure 9. Validation and accuracy prediction results showing the correlation between standard CS and CS values of the E4, I1, and K4 effective frequency sets across all profiles.

Boonsakul, P., S. Buddhawong, S. Towprayoon, S. Vinitnantharat, D. Suanburai, and K. Wangyao. 2021. Applying electromagnetic surveys as pre-screening tools prior to open dump mining. J. Mater. Cycles Waste Manage. 23 (4):1518–30. doi:10.1007/s10163-021-01232-5.

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Data availability statement

The data that support the findings of this study are available from the corresponding author, [KW], upon reasonable request.