Well Installation and Field Report
La Urca, Santiago, Pimienta
And
Nuevo Amanecer, Potrerillos
Cortes, Honduras
Prepared by:
Primero Agua
Prepared for:
Washington Overseas Mission
(Washington, Missouri),
Engineers Without Borders
(St. Louis Professional Chapter & Missouri S&T University Student Chapter)
And
Washington Missouri Rotary Club
March 2012
Table of Contents
Introduction ..................................................................................................................................... 1
Background ..................................................................................................................................... 1
Goals and Objectives ...................................................................................................................... 2
Equipment and Methods ................................................................................................................. 2
La Urca #1....................................................................................................................................... 3
La Urca #2....................................................................................................................................... 4
Potrerillos #1 ................................................................................................................................... 6
Summary ......................................................................................................................................... 7
Conclusions ..................................................................................................................................... 7
Figures............................................................................................................................................. 8
Appendix A ..................................................................................................................................... 9
Appendix B ................................................................................................................................... 10
Introduction
Between February 15 and 25, 2012, the Primero Agua Drill Team (Team) gathered in Honduras
to install fresh drinking water wells in the villages of La Urca and Nuevo Amanecer (Potrerillos)
outside the municipality of Santiago, Pimienta, Cortes, Honduras. There were six US volunteers
that led the drilling and well installation: Jay Quattlebaum, Tommy Mouser, Tim Fetterman,
Dale Lohmeyer, Leo Meyer, and Mark Underwood. Tommy and Tim reside in Texas, and the
remainder resides in or near Washington, Missouri. All but Mark were returning volunteers,
with Jay and Tommy returning frequently over the last decade. There was local assistance from
Dr. Raul Ugarte in the form of logistical support, and assistance with drilling activities by local
young men: Fernando, Jacob, Geraldo, and Randy.
It should be mentioned that upon arrival at each of the drill sites, the local village men and older
boys were quick to jump into action and assist the Team. At each site, they cleared brush and
rocks, leveled the site of bumps and ruts, and participated in the various other setup activities as
well as drilling activities. They also shared materials that they had available, such as concrete
blocks, as well as providing information about the local groundwater to the extent that they had
knowledge. In addition, the local people of La Urca shared generously of their harvests of
bananas, plantains, corn, papayas, and squash; their embrace of the improvements to their village
as provided by the addition of clean sources of water were outward and obvious in their actions
and reactions.
Background
The La Urca area is inhabited by 45 families, and water was supplied by four hand dug wells. A
short distance west of La Urca is the village of Potrerillos where another 19 families live and
find water from hand dug wells. The hand dug wells were all located within a sedimentary plain
of the Rio Ulua where groundwater could be found at shallower depths and somewhat easier
digging by hand. Most of the hand dug wells were located within the flood plain of the Rio Ulua
and thus were subject to periodic inundation by flood waters; they were accessed by buckets and
a line thrown over a pulley or stick. Only one of the hand dug wells was covered leaving the
remainder completely open to the environment and subject to leaf litter and other debris, insects,
and overland flow from large rain events. It can be noted that the people of La Urca and
Potrerillos are allegedly squatters that possess little and subsist through simple farming by hand.
Many of the children do not attend school.
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012
La Urca and Potrerillos lie along an escarpment of limestone rock that raises out of the flood
plain of the Rio Ulua, which is a major river transecting Honduras and San Pedro Sula. All of
the hand dug wells were within the alluvial plain of the river, and most were subject to
inundation during extreme flooding events. The escarpment appears to be along the erosional
front of the Rio Ulua that was subsequently backfilled by river sediments and flood deposits of
the meandering river. Based on available geologic descriptions and field observations, the visible
surface rocks forming the escarpment are part of the Cretaceous age Yojoa Group comprised
prevalently of limestone rocks. Beneath the Yojoa Group are thick intrusive granodiorites and
granites thought to be of the Atima Group also of Cretaceous age. At the western extent of
Potrerillos village lies a fault as identified by a previous geologic study that also appears to direct
the flow of the Rio Ulua toward the south. From maps of the area, the Rio Ulua flood plain
appears to lie approximately 120 ft above mean sea level (msl). Thus, from this information, it
appears that the drill sites at both La Urca and Potrerillos were at approximately 10 ft above the
flood plain, or approximately 130 ft msl. Figure 1 shows the location of the villages of La Urca
and Potrerillos as well as the drilling locations.
Goals and Objectives
The goal of the field activities was to install as many drinking water wells as time allowed, and
outfit the wells with hand pumps. Toward this goal, two wells were installed and outfitted with
pumps: La Urca #1 and La Urca #2. A third borehole was drilled in Potrerillos but complications
from caving sands and cobble layers, noted further below, led to it being abandoned. The overall
objective of Primero Agua is to provide fresh drinking water to impoverished areas of Honduras
close to the Pimienta area where the field office lies. While the efforts toward this objective
continue to be refined and evolve, the progress that can be noted in this report indicates that this
objective is being met.
Equipment and Methods
In August 2011, Primero Agua took possession from customs of a Central Mine Equipment
(CME) - 75 drill rig. The truck on which the CME drill rig sat was a 1997 Ford F-700, and the
age of the truck was greater than normally allowed clearance from customs. Dr. Raul Ugarte
spearheaded an ‘exception’ for the rig to allow it passage through customs. Thus, the February
endeavor was only the second field session for the Primero Agua Drilling Team. The drill rig
utilizes mud-rotary techniques for drilling, and the standard bit size is 8 7/8-inch diameter (i.e., a
tri-cone bit). The mud-rotary method requires drilling with a slurry of bentonite (referred to as
‘gel’ or ‘driller’s mud’) to coat the borehole and entrain the cuttings from the bit to the surface.
Thus, there is considerable water consumed during the drilling as necessary to maintain the gel
slurry during all drilling. The water was provided by two polyethylene tanks (capacity
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012
approximately 285 gallons each), with one stationary at the drill site, and the other inside the bed
of a pickup used to transport the water from its source; the source for this project was the Rio
Ulua where access was approximately 10 minutes from the La Urca sites (and 15 minutes from
the Potrerillos site) through a former cane field from the drilling locations. The water was
pumped via a small utility pump up an embankment (approximately 20 vertical feet) and into the
transport tank.
La Urca #1
La Urca #1 was drilled on February 17 and 18, 2012. The selection of the La Urca #1 Site was to
provide water to approximately six homes within 100 ft of this location. It was sited along the
eastern side of the road along a steep section of the escarpment. The road cut along the
embankment indicates that the geology is composed of decomposed limestone that forms
interbedded layers of clay and limestone at various levels of decomposition. The drilling mud
turned yellow from the material, and the level of decomposition appears to reduce with depth as
indicated by more rock chips in the gel slurry and slightly harder drilling with depth. At a depth
of 42 ft below ground surface (bgs), there was a sudden break in lithology that significantly
impeded the speed of the drilling advance (i.e., the drilling was significantly harder), and the
mud became more reddish with the change in lithology. Cuttings also indicated the presences of
angular pieces of quarts and feldspars. By the depth of 47 ft, the circulating gel slurry was not
possible to maintain in the borehole due to losses of the fluid within the formation, and the
drilling was terminated. It is interpreted that this zone is highly fractured and thus highly
permeable, and the permeability was too great to maintain the gel slurry in the borehole.
Appendix A provides a well log that describes the geology and well construction.
The well was constructed in the borehole of La Urca #1 by lowering a total of 49 ft of 4-inch
PVC casing with 37 ft of blank casing atop of 10 ft of slotted casing just off the bottom of the
borehole. Approximately two ft of blank casing was left sticking above the ground surface. The
bottom was sealed by slotting approximately four inches of the bottom of the slotted pipe length
using a hack saw, heating (with a fire made by the local men), and bending to form a cap; the cap
was further taped to prevent potential entry by sand. Filter pack material composed of local river
sediments screened to size between approximately 1/8-inch and 1/4-inch was emplaced from the
bottom of the borehole to approximately 12 ft bgs. A surface seal of concrete was emplaced
from approximately 12 ft bgs to the surface, with a 4-inch pad of concrete emplaced to hold the
pump housing and provide standing area surrounding the pump. The pad was approximately 3 ft
by 4 ft in area, and the pump was placed approximately in the center of the pad with the handle
and long axis of the concrete pad positioned parallel to the road. Photos showing the completed
well at La Urca #1 are provided in Appendix B.
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012
Development of the well consisted of air-lifting water and residual drilling fluids from the well
using an Ingersoll-Rand compressor. Approximately two hours of air lifting was performed with
many hundreds of gallons evacuated from the well prior to installation of the pump. Water flow
during the development was initially very turbid with clearing of the water occurring by about 20
minutes of air lifting. By completion of the nearly two hours of air lifting, the water had a slight
residue of turbidity.
The pump (an India Mark II Deep Well Hand pump manufactured by Balaji) was lowered to a
depth of approximately 40-to-41 ft bgs where it was suspended from 1 ½-inch galvanized riser
pipe that was attached to an assembly mount embedded in the concrete pad. Within the riser
pipe was a 3/8-inch rod that connected the pump to the handle. Approximately one-half gallon of
weak bleach was dumped into the well prior to closing the pump housing. Once the hand pump
was installed, the initial pumping indicated some residual turbidity (i.e., from the driller’s mud)
that cleared quickly. The pump was installed on February 19, 2012, and the static groundwater
level was 30.6 ft below top of casing (TOC) (or 28.6 ft bgs). The water temperature was
estimated to be approximately 80 degrees Fahrenheit, and its taste was without apparent minerals
or iron.
La Urca #2
La Urca #2 was drilled starting February 19 and ending February 21, 2012. The selection of the
La Urca #2 Site was to provide water to a cluster of homes also within 100 ft of this location. La
Urca #2 is approximately 525 ft west of La Urca #1. Similar to La Urca #1, it was sited along
the northern side of the road along a road cut that steps its way to the escarpment located
approximately 100 ft toward the north. Similar to La Urca #1, the road cut along the
embankment indicates that the geology is composed of decomposed limestone that forms
interbedded layers of clay and limestone at various levels of decomposition. This limestone is
inferred to be part of the Yojoba Group (Grupo Yojoba) that is Cretaceous age. The drilling
mud turned yellow from the material, and the interbedded hard and soft layers of this material is
found to a depth of 80 ft bgs at this location. At 80 ft bgs, there is a sudden change in lithology
that changed the mud color to gray. This interval continues to the total depth of 187 ft with
alternating hard and soft layers and increasingly higher proportion of harder intervals with depth.
The mud returned chips of white (felsic) plagioclase, iron-stained quartz, and undifferentiated
mafic rock material as well as gray clay balls noted especially within softer drilling intervals; by
contrast, harder drilling intervals provided relatively more rock chips without clay balls of mud.
The rock chips indicate that the rock is a granodiorite, and review of available literature indicates
that this granodiorite is part of a thick intrusive sequence that is part of the Atima Group (Grupo
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012
Atima) that is Cretaceous age. Drilling was continued to the maximum depth (187 ft bgs)
allowed by the 190 ft of drilling rods. The maximum depth was drilled due to the apparent lack
of permeability; that is, the borehole did not appear to have permeable zones as evidenced by a
lack of water production and sustained level of gel slurry in the borehole during the idle
overnight period on both February 19 and February 20. Appendix A provides a well log that
describes the geology and well construction.
The well was constructed in the borehole of La Urca #2 by lowering 189 ft of 4-inch PVC
casing: 167 ft of blank casing and 20 ft of slotted casing off the bottom of the borehole with
approximately two ft of blank casing left sticking above the ground surface. The bottom of the
screened interval was sealed using the method heating and folding over strips of the casing as for
La Urca #1, described above. Filter pack material composed of local river sediments screened to
size between approximately 1/8 -inch and 1/4-inch was emplaced from the bottom of the
borehole to approximately 40 ft above the bottom of borehole. The well was air lifted for an
initial period of approximately 1 hour, followed by placement of gravel having a size range
between approximately 1/4-inch and 1/2–inch to within approximately 30 ft of the ground
surface. Sand was placed in the annular space up to a depth of approximately 12 ft bgs. A
surface seal of concrete was emplaced from approximately 12 ft bgs to the surface, with a 4-inch
pad of concrete emplaced to hold the pump housing and provide standing area surrounding the
pump. The pad was approximately 3 ft by 4 ft in area, and the pump was placed approximately in
the center of the pad with the handle and long axis of the concrete pad positioned parallel to the
road. Photos showing the completed well at La Urca #2 are provided in Appendix B.
Development of the well consisted of air-lifting water and residual drilling fluids from the well
using an Ingersoll-Rand compressor on February 21 and February 23, 2012. Altogether,
approximately two hours of air lifting was performed with many hundreds of gallons evacuated
from the well development prior to installation of the pump. After setting for 2 days, the final air
lifting occurred on February 23, and the static groundwater level prior to air lifting was 21.7 ft
below TOC (or 19.7 ft bgs). The initial water to flow from the well during air lifting was clear
with the later water showing high turbidity from the residual driller’s mud. The turbidity never
cleared up, but significantly diminished during air lifting. There was noticeably lower water
volume generated from La Urca #2 than La Urca #1, in spite the much greater well depth of La
Urca #2. The monitoring of the groundwater level at conclusion of the air lifting indicating a
one-foot rise in water level from 100 ft below TOC to 99 ft below TOC to occur in 15 seconds.
This suggested sufficient recharge to make a viable well. At completion of the air lifting, a full
gallon of bleach was dumped in the well.
The pump (an India Mark II Deep Well Hand pump manufactured by Balaji) was lowered to a
depth of approximately 80-to-81 ft bgs where it was suspended from 1 ½-inch galvanized riser
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012
pipe and internal 3/8 –inch pump rod which attached to an assembly mount embedded in the
concrete pad. The pump was installed on February 23, 2012.
Potrerillos #1
After the second well was drilled in La Urca, the drill rig was moved to the village of Potrerillos
where approximately 19 families reside. The selected site was labeled Potrerillos #1, and it was
drilled on February 22, 2012. The Potrerillos #1 site was located at the eastern end of the village
near a hand-dug well that had gone dry due to sediment sloughing from the sides of the hand dug
well and filling the saturated zone; thus, this area of the village had the greatest distance to travel
to get to a viable hand-dug well. This drill site was approximately 1 mile north of La Urca #2.
The bottom of the nearby dry hand-dug well was measured at 14 ft depth, and according to the
local men, the well had been dug to 21 ft bgs with water found at 19 ft bgs. If their estimates
were accurate, then the well had backfilled approximately 7 feet. There was no evidence of
major collapse of the sidewalls of the well which had a diameter of approximately 4 ft. The local
men also believed that the addition of the nearby levee had led to drop of the water table in the
area.
The drilling site was approximately 8 to 10 ft vertically above the hand-dug well. The intent was
to locate the site such that the river sediments were intercepted and the Yojoa Group limestone
and underlying Atima granodiorite avoided. The escarpment at this location was several hundred
feet northward of the drill site, but it was not evident of the limestone formation was in place
beneath the drill site. Upon commencement of drilling there was the presence of sandy
sediments from the start of drilling, and the prevalence of limestone material as noted by the
dominance of yellow drilling mud suggests that the sediments were prevalently displaced
limestone (e.g., float) from the nearby escarpment. The initial 22 ft of drilling was through
sediment composed primarily of weathered limestone rock (interpreted as colluvium or the
primary component of the sedimentary material) mixed with clay and river sediments. As the
drilling progressed, the mud became more yellow indicating more calcareous mud material with
depth. At 22 ft, there was a sudden break in lithology and the drilling was without resistance
until 26 ft bgs. The material between 22 ft bgs and 26 ft bgs was composed primarily of fine to
coarse sand, with apparent coarsening downward. When the drill bit was lifted, the sand in this
interval collapsed and circulation of the mud slurry was lost due to infiltration into the sand
interval. The driller added thicker slurry of gel and was able to restore circulation by coating the
sidewalls of the borehole and advance. The advance of the drill bit met a layer of cobbles of
indeterminate thickness beginning at 26 ft bgs. Drilling approximately 4 ft into the layer of
cobbles (i.e., down to 30 ft bgs) de-stabilized the sand horizon, and circulation was again lost.
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012
The cobble horizon (as inferred by primarily from shaking of the drill rig) presented some very
tough drilling. The determination was made to abandon the hole due to this combination of
cobbles and caving sands and limited resources (i.e., gel material) to offset these pitfalls.
Groundwater was measured at a depth of approximately 26.9 ft bgs. Appendix A provides a
well log that describes the geology and drilling methods.
Summary
Two water wells and pumps were drilled in La Urca, and an attempt to drill a third well was
made to drill in the village of Potrerillos. This field effort occurred between February 16 and
February 25, 2012. A summary of each is provided in the follow:
 La Urca #1 is 47 ft deep with groundwater provided by an apparent fractured zone
between approximately 42 and 47 ft bgs. The initial depth to groundwater prior to
placement of the pump was 28.6 ft bgs.
 La Urca #2 is 187 ft deep with groundwater provided by fractures encountered in the
borehole. The initial depth to groundwater was 19.7 ft bgs.
 Potrerillos #1 was drilled to a depth of approximately 2.5 ft bgs. However, the hole was
abandoned due to the loss of driller’s mud circulation and the presence of caving sands
between 22 and 26 ft bgs as well as a cobble layer (of indeterminate thickness) between
approximately 26 and 30 ft bgs that destabilized the borehole due to vibration of the drill
rig and drill stem.
Conclusions
The drilling efforts endeavored during this field session provided several noteworthy
conclusions. These are provided as follows.
 The addition of new wells to areas where only hand-dug wells exist improves the quality
of water. The impact is immediate to the locals as witnessed by immediate and abundant
use including passing cyclists.
 Drilling in this area of Honduras provided successful wells at two locations. The geology
was composed of decomposed rock and indurated rock, and the mud-rotary methods
employed were successful to provide wells.
 Drilling where caving sands and cobbles occur including coastal and alluvial plains do
not provide conditions where mud-rotary drill methods are successful. In shallow drilling
especially where caving sands and cobbles are found, use of a hollow-stem auger is more
likely to succeed.
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La Urca and Potrerillos Villages, Honduras
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March 2012
Figures
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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March 2012
Appendix A
Borehole and Well Logs
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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March 2012
Appendix B
Photos
Well Installation and Field Report
La Urca and Potrerillos Villages, Honduras
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Primero Agua
March 2012