CC SR 20170620 P - Portuguese Bend Dewatering WellsRANCHO PALOS VERDES CITY COUNCIL
AGENDA REPORT
AGENDA DESCRIPTION:
MEETING DATE: 06/20/2017
AGENDA HEADING: Consent Calendar
Consideration and possible action to receive and file a report on the status of the
Portuguese Bend Landslide Dewatering Well Project.
RECOMMENDED COUNCIL ACTION:
(1) Receive and file this report.
FISCAL IMPACT: None
Amount Budgeted: N/A
Additional Appropriation: N/A
Account Number(s): N/A
ORIGINATED BY: James Flannigan, Assistant Engineer//
REVIEWED BY: Terry Rodrigue, PE, Interim Director of Public Works
APPROVED BY: Doug Willmore, City Manager JVr
ATTACHED SUPPORTING DOCUMENTS:
A. Drill Locations (page A-1)
B. Photos of Drilling Operations (page B-1)
BACKGROUND AND DISCUSSION:
The Portuguese Bend Landslide Dewatering Well project consisted of drilling
dewatering wells at various locations within the Portuguese Bend Landslide area. Drill
locations are depicted on the attached map (Attachment A).
Drilling began on Well #1 in late July 2016 and continued throughout early September
2016. The contractor initially drilled 200 feet before hitting rock. Various drilling tools
and techniques were explored to enable penetration of the rock layer. After several
months of drilling, the contractor completed drilling to a depth of 400 feet, but no water
was found at that depth. Due to a lack of water, the well has been filled-in and
construction concluded. Photos of drilling operations can be seen in Attachment B.
Well #2 drilling started mid-September 2016. This well was drilled to a final depth of
405 feet. Minimal ground water was found, however, the estimated production amount
was too low to meet acceptable threshold minimums and a decision was made to
discontinue developing this well. Therefore, the well has been filled-in.
1
Drilling for Well #3 started mid-October 2016 and was completed in late November.
The well produced approximately 30 gallons of water per minute for about 6 days. The
outflow was artesian. This site was a good candidate for developing into a dewatering
well; however, restrictions associated with working in the Nature Preserve prevented
progress on this well and installation of the electrical equipment was never completed.
The well is completely constructed, without the electrical components, and has been
capped for potential future use, barring damage from land movement.
Well #4 drilling started late November 2016 and was completed in early December
2016. The final well depth was approximately 400 feet below grade and the presence of
ground water was not substantial enough to consider this location a success. As a
result, well development at this site was discontinued. Construction of the well is
completed without the electrical components and the well has been capped. Due to low
water production, we do not anticipate utilizing this well in the future.
The location of Well #5 was chosen because of the success at well #3. Drilling started
in mid-December. A depth of about 90 feet was achieved. Heavy rains made the
ground too muddy to get back to the site and the erosion eventually deteriorated nearby
dirt roads and surrounding trails within the Preserve to the point where they became un -
drivable. Due to environmental concerns associated with working in the Nature
Preserve, the crews were unable to repair roads to get back to the job site and complete
drilling the well. This well location has been capped.
Staff was informed by Wildlife Agencies that all work was to be halted on this project
until the updated Natural Community Conservation Program (NCCP) Plan was
approved. In the meantime, through negotiations, Staff was given approval to install a
new HDPE plastic effluent pipe to replace the existing dewatering PVC pipe. This pipe
was installed during March and April this year. It runs from the north end of Peppertree
Drive to the ocean. Photos of the replacement dewatering line are provided in
Attachment B.
The total amount expended on this project to date is $232,833. In summary, 5 well sites
were attempted; however, for various reasons discussed above, there are no
operational wells to date in the Portuguese Bend Landslide area.
2
DRILL LOCATIONS
r
ova
4 rl
Aiol
- qr I SHI BASHI
FARM TRAIL
t +
AP
e•�r�e� tsr�, � � +� . 3
URMA RD.
lip
y
�_lj '�._ � v �
w •
'A. 611
lai
A-1
,nl
f