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A Technologically Appropriate Method for Measuring the S pecific C apacity of R ope- P ump W ells. John S. Gierke 1 , Essa L. Gross 1 & Elizabeth A. Myre 2 - PowerPoint PPT Presentation
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A Technologically Appropriate
Method for Measuring the Specific
Capacity of Rope-Pump Wells
John S. Gierke1, Essa L. Gross1 & Elizabeth A. Myre2
1Department of Geological & Mining Engineering & Sciences2Department of Civil & Environmental Engineering
Michigan Technological University
Antoinette Kome
SNV Nicaragua
Outline
Introduction &
Objectives
Methodology
Results & Conclusions
Introduction:Water Supply Issues for Developing Countries
• Practically no information exists on the capacity of rural wells
• Many areas suffer from lack of water during the dry season
• Management agencies have no information to develop water management plans
• Lack of technical and economic resources prevents the collection of performance and monitoring data
Rope Pumps
Originated in Nicaragua (1980s), has since proliferated there
Usage outside of Nicaragua has been limited, can be driven manually or with wind
Affordable and readily maintained
Can they be adapted for using in pumping tests?
60’
Design and test a method to characterize
the productivity of existing rope-pump
wells in rural areas of developing
countries
Research Objectives
Monitor seasonal changes in SWLs
and specific capacities of rope-
pump wells in an area that
experiences distinct rainy and dry
seasons.
Santa Rita
Study Area
Regional Geology
Tpc - Coyol Group
Fractured ignimbrites,
tuff, andesite, basalt
X XXX
Source: INETER
HydrogeologyNo de Pozo: 126/02/02
Coordenadas: L. Nort L.Oest
200 pies 60.96 m
50 pies 15.24 m
160 pies 48.768 m
5 gpm 1.1354 m3/h
50 pies 15.24 m
18 gal. 68.13 litros
46 gal. 174.11 litros
8 gal. 30.28 litros
gal. 0 litros
8 gal. 30.28 litros
gal. 0 litros
80 gal. 302.8 litros
EMPRESA NICARAGUENSE DE ACUEDUCTOS RURALES Y ALCANTARILLADOSGerencia de Acueductos Rurales
REGISTRO DE POZOS
REVESTIMIENTO PERFIL GEOLOGICO DATOS GENERALESDepartamento: Chontales
Municipio: Juigalpa
Comunidad: Santa Rita
Elevacion (msnm):
0'-20' Basalto erocionado Gris(GR) Perforador: Carlos Largaespada
Supervisor-Geologo: Luis Meza Hurtado
20'-30 Basalto Compacto Fecha de inicio: 2/14/06
Fecha de finalizacion: 2/15/06
30'-60' Toba Calcitica (Mr) Metodo(s): Rotativo
Diametro(s) de perforacion: 77/8" y 51/4"
No de barras: 20
60'-90' Basalto (GR) Profundidad total:
NEA:
NFA:
90'-100' Toba Aglomeratica (MR) Caudal:
Metodo de bombeo:
Tiempo de bombeo: horas
100'-150' Basalto con pigmentaciòn cristalinaProfundidad del agua al final del bombeo:
DISTRIBUCCION DEL TIEMPO
Total de horas trabajadas 18:19
Tiempo de perforacion 6:57
150'-160' Basalto Fracturado Total de Tiempo muerto: 1:34
Causas del tiempo muerto:
Lluvias
160'-200' Basalto (Gr) con presencia de cristalReparacion y mantenimiento 0:34
Falta de materiales
Fuerza mayor
Falta de acceso
Problemas de perforacion
Alimentacion 1:00
Desarrollo 1:45
Otras actividades 8:03
CONSUMO DE DIESEL
Sonda de perforacion
Compresor
Camion Portasonda
Camion del compresor
Camioneta de apoyo
Camioneta supervision
TOTAL
NOTAS:
La perforac—n se desarrollo sin ningn problema, los tubos que se usaron para el encamisado del pozo, fueron de los que se sacaron en la salida de Apompua El Portillo, para el mismo se utilizaron un total de 22 tubos de 4" x 3 Mtrs.
No de Pozo: 126/02/02
Coordenadas: L. Nort L.Oest
200 pies 60.96 m
50 pies 15.24 m
160 pies 48.768 m
5 gpm 1.1354 m3/h
50 pies 15.24 m
18 gal. 68.13 litros
46 gal. 174.11 litros
8 gal. 30.28 litros
gal. 0 litros
8 gal. 30.28 litros
gal. 0 litros
80 gal. 302.8 litros
EMPRESA NICARAGUENSE DE ACUEDUCTOS RURALES Y ALCANTARILLADOSGerencia de Acueductos Rurales
REGISTRO DE POZOS
REVESTIMIENTO PERFIL GEOLOGICO DATOS GENERALESDepartamento: Chontales
Municipio: Juigalpa
Comunidad: Santa Rita
Elevacion (msnm):
0'-20' Basalto erocionado Gris(GR) Perforador: Carlos Largaespada
Supervisor-Geologo: Luis Meza Hurtado
20'-30 Basalto Compacto Fecha de inicio: 2/14/06
Fecha de finalizacion: 2/15/06
30'-60' Toba Calcitica (Mr) Metodo(s): Rotativo
Diametro(s) de perforacion: 77/8" y 51/4"
No de barras: 20
60'-90' Basalto (GR) Profundidad total:
NEA:
NFA:
90'-100' Toba Aglomeratica (MR) Caudal:
Metodo de bombeo:
Tiempo de bombeo: horas
100'-150' Basalto con pigmentaciòn cristalinaProfundidad del agua al final del bombeo:
DISTRIBUCCION DEL TIEMPO
Total de horas trabajadas 18:19
Tiempo de perforacion 6:57
150'-160' Basalto Fracturado Total de Tiempo muerto: 1:34
Causas del tiempo muerto:
Lluvias
160'-200' Basalto (Gr) con presencia de cristalReparacion y mantenimiento 0:34
Falta de materiales
Fuerza mayor
Falta de acceso
Problemas de perforacion
Alimentacion 1:00
Desarrollo 1:45
Otras actividades 8:03
CONSUMO DE DIESEL
Sonda de perforacion
Compresor
Camion Portasonda
Camion del compresor
Camioneta de apoyo
Camioneta supervision
TOTAL
NOTAS:
La perforac—n se desarrollo sin ningn problema, los tubos que se usaron para el encamisado del pozo, fueron de los que se sacaron en la salida de Apompua El Portillo, para el mismo se utilizaron un total de 22 tubos de 4" x 3 Mtrs.
200’
50’
160’
0-20’ Weathered Basalt
20-30’ Compacted Basalt
30-60’ Tuff (cemented ash deposit)
60-90’ Basalt
90-100’ Tuff
100-150’ Basalt
150’-160’ Fractured basalt
160-200’ Basalt
Testing and Monitoring Approaches
• Monthly manual pump tests in triplicate at 3 wells
• Each test included pumping, equilibrium, and recovery phases
• A conventional step-drawdown test performed in one well
Manual Pumping Test Regime
• Pump 60 – 90 gal
• Approximate rate of 5 gpm
• Well allowed to recover for at least an hour
• Triplicate tests
After Gross (2007)
Straight-Line & Equilibrium Drawdown Methods
Seasonal Change in SWLs
Average dry season drop = 6 ftAverage dry season drop = 6 ft
DRY RAINY
Sta
tic W
ater
Lev
el
(ft
bgs)
Seasonal Changes in Specific Capacity
Well
SWL Change
(ft)
SWL Change (% available
water column)*
% Change Specific Capacity
1 - 6.6 - 4.0 % - 15 %
2 - 4.4 - 2.5 % - 26 %
3 - 6.3 - 3.5 % --
4 - 7.9 - 4.8 % - 81 % *Assuming 200’ well
Drop in SWL (ft) from Dec 2006
Spe
cific
Cap
acity
(gp
m/f
t)
Traditional pump test profile 9/25/07
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Elapsed time (hrs)
Dra
wd
ow
n (
ft b
tc)
5 gpm 15 gpm
25 gpm
37 gpm
Comparison of Pumping Test Methods
Well 4
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
35 36 37 38 39 40 41 42 43 44
SWL (ft btc)
Sp
ec
ific
ca
pa
cit
y (
gp
m/f
t)
Equilibriumapprox
Non-equilibriummethod -recovery curve
Non-equilibriummethod - pumpcurve
Trad Equilibriumapprox
Trad Non-equilibrium-pumpcurve
Trad Non-equilibrium-recovery curve
Linear (Non-equilibriummethod -recovery curve)Linear(Equilibriumapprox)
Linear (Non-equilibriummethod - pumpcurve)
Prueba perfil
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0 500 1000 1500 2000 2500
Prueba perfil
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0 500 1000 1500 2000 2500
Spec. cap values calculated from conventional test:
equilibrium approx
recovery curve
pump curve
Spec. cap values calculated from manual tests:
equilibrium approx
recovery curve
pump curve
Sp
ecif
ic C
apac
ity
(gp
m/f
t)
Curve Matching: Papadopolus-Cooper (1967) using AQTESOV
10-1
100
101
102
0.
1.6
3.2
4.8
6.4
8.
Time (min)
Dis
plac
emen
t (ft)
Obs. Wells
Church Well
Aquifer Model
Confined
Solution
Papadopulos-Cooper
Parameters
T = 366.9 gal/day/ftS = 0.2002r(w) = 0.177 ftr(c) = 0.177 ft
10-1
100
101
102
0.
1.6
3.2
4.8
6.4
8.
Time (min)
Dis
plac
emen
t (ft)
Obs. Wells
Church Well
Aquifer Model
Confined
Solution
Papadopulos-Cooper
Parameters
T = 629.6 gal/day/ftS = 0.01119r(w) = 0.177 ftr(c) = 0.177 ft
Comparison of Data Analysis Methods
MethodAccounts for
casing storage?T (gpd/ft)
JSL(pumping)
no 296
GMS-MODFLOW Calibration(pumping)
yes 364
P-C AQTESOLV(pumping)
yes 367
JSL (late recovery)
no 438
GMS-MODFLOW Calibration(pumping and recovery, 1)
yes 528
Equilibrium Drawdown(equilibrium)
n/a 593
P-C AQTESOLV(pumping and recovery)
yes 630
GMS-MODFLOW Calibration(pumping and recovery, 2)
yes 653
Conclusions: Method
3. Recovery data easiest to collect and yields representative well behavior, equilibrium behavior easier to analyze
4. Modifications of wells for manual pump test are minor & economical
1. Wells are currently used at 1/10th of their maximum capacity
2. Although the manual pump rate is low, results are representative of well behavior at high rates, at least 7X higher
Conclusions: Seasonal Effects
2. Current water demand places a negligible stress on the aquifer compared to seasonal changes in the static water level
3. Systematic monitoring is needed for management
1. Changes in specific capacity were observed for even slight changes (~ foot) in SWL
Acknowledgements
We would like to acknowledge the following people for their assistance in this study:
Gregg Bluth, Fernando Flores, Luis Meza, Denia Acuña, Evelio Lopez , Ivan Palacios, Elisena Medrano, Luis
Palacios, and the Families of Santa Rita
Financial Support:• National Science Foundation PIRE 0530109• DeVlieg Foundation• SNV Nicaragua• U.S. Peace Corps• MTU d80 Center & GMES Department