Drilling Water BMPs

April 12, 2012 Drilling Water BMPs
Best Management Practices for Managing Water at Well Drilling Sites
Depending on site-specific hydrologic conditions, the construction of water supply,geothermal, and
other wells may produce large volumes of water during the drilling process. The water produced from
the drilling activity is often laden with rock cuttings, silts, clays, etc.referred to as “suspended solids”.
The suspended solids can be substantially increased if drilling water is allowed to flow overland and
erode the ground surface. The transport of suspended solids is considered a non-point pollution source
and may adversely impact surface water, wetlands, stormwater basins, etc. Discharges of this material
that result in a stream standard violation are illegal and may be subject to a civil penalty assessment of
up to $25,000 per day for each violation.It is the responsibility of the well contractor, permit holder and
general contractor to manage through volume reduction and treatment,water generated onsite prior to
discharge.
This document is intended to introduce contractors to strategies or ‘best management practices’
available to avert impacts from drilling operations.Additional measures or alternative practices may be
necessary dependent upon the site.Many of the practices used to control stormwater on other
construction sites may be applied to drilling operations as the end goals are the same:reducing
sediment runoff.DWQ’s Stormwater Best Management Practices Manual offers an additional, more
detailed resource and may be found here:
http://portal.ncdenr.org/web/wq/ws/su/bmp-
manual .Engineered solutions are typically
required where large volumes of water are
expected or a large number of wells are
installed in one area.
What is a BMP?
BMPs are ‘best management practices’
implemented onsite to treat or limit pollutants
(e.g., suspended solids) from entering surface
waters or impacting groundwater. BMPs may include altering processes or installing structures to
reduce, retain,or treat sediment-laden water. BMP ‘processes’include altering drilling rig air pressure
to reduce the volume of water generated, drilling in phases, limiting the number of active drill rigs
onsite, use of diverters,and reducing drill bit size to the minimum size necessary. BMP ‘structures’
include installation of sediment ponds, filter bags, fabric lined trenches,’frac’tanks, filter boxes, use of
flocculants,and filter strips.
April 12, 2012
What is the impact of muddy water
Sediment leaving your site can blanket the stream
and aquatic plants.The influx of turbid water to a stream may
reported in Nephelometric Turbidity Units (NTUs).
NTUs for trout waters.
What are some BMPs DWQ expects to be implemented at drilling sites?
The selection of BMPs used onsite is dependent upon several factors
include test well yield (how much water do you expect
stormwater inlet,size of drilling operation (5 wells or 200 wells),
vegetative cover, weather or season of the year, and terrain. Drilling contractors should carefully
consider and budget as necessary bids on drilling
other entities (permit holders, general contractors, etc.) will be installing
managing BMPs.Regardless of adequate planning, modific
occurring onsite are often necessary.
Please note that many treatment structures require that water be captured at the drill rig
and transported to the structure directly
of a diverter system (see photo right
lined trench in a manner whereby no additional sediment is added to the water.
Examples of BMPs being used on well construction sites to address turbid water
include:
allowing water to flow through the bag. Sediment captured in the bag
can be spread on vegetated land following use. It is important to
consider estimated flow
rate and sed
when evaluating this
option.
of water through the bag
can be as high as 800 gpm.
• Trench:Establishing geotextile lined trenches is a proven
method of transporting sediment-laden water from the
rig to a treatment structure or to a vegetated filter strip.
With the use of weirs and a low gradient,
begin to drop out of suspension while moving in the trench.
Drilling Water BMPs
What is the impact of muddy water, suspended solids,and turbidity being released from my site?
blanket the stream bottom and smother fish eggs,macroinvertebrates
of turbid water to a stream may also lead to an increase in water
temperature and a decrease in dissolved oxygen
stresses the aquatic community.Turbid water carrying sediment
may pickup nitrogen, phosphorus or other pollutants that
adhere to sediment particles.These pollutants are
deposited into the receiving water body. Turbidity is
of water clarity that is usually assessed with a meter and
reported in Nephelometric Turbidity Units (NTUs).The standard for surface water bodies begins at
What are some BMPs DWQ expects to be implemented at drilling sites?
The selection of BMPs used onsite is dependent upon several factors that differ between sites
test well yield (how much water do you expect), proximity to surface water bodies,
size of drilling operation (5 wells or 200 wells),amount of overburden, soil types,
vegetative cover, weather or season of the year, and terrain. Drilling contractors should carefully
budget as necessary bids on drilling jobs to include BMPs or ensure contractually
other entities (permit holders, general contractors, etc.) will be installing and be responsible for
Regardless of adequate planning, modification of existing BMPs to address changes
occurring onsite are often necessary.
treatment structures require that water be captured at the drill rig
and transported to the structure directly.Capturing the water is typically done with use
right). Preferably, water is transported through a pipe or
no additional sediment is added to the water.
of BMPs being used on well construction sites to address turbid water
include:•Sediment Filter Bag:This device traps sediment while
allowing water to flow through the bag. Sediment captured in the bag
can be spread on vegetated land following use. It is important to
consider estimated flow
rate and sediment size
when evaluating this
option.Initial flow rates
of water through the bag
Establishing geotextile lined trenches is a proven
laden water from the drill
treatment structure or to a vegetated filter strip.
With the use of weirs and a low gradient,sediment can
begin to drop out of suspension while moving in the trench.
Drilling Water BMPs
being released from my site?
macroinvertebrates,
also lead to an increase in water
temperature and a decrease in dissolved oxygen, which further
rbid water carrying sediment
pickup nitrogen, phosphorus or other pollutants that
These pollutants are ultimately
. Turbidity is a measure
with a meter and
ter bodies begins at 10
differ between sites. These
), proximity to surface water bodies,proximity to
amount of overburden, soil types,
vegetative cover, weather or season of the year, and terrain. Drilling contractors should carefully
contractually that
and be responsible for
ation of existing BMPs to address changes
treatment structures require that water be captured at the drill rig
se
through a pipe or
This device traps sediment while
allowing water to flow through the bag. Sediment captured in the bag
can be spread on vegetated land following use. It is important to
April 12, 2012 Drilling Water BMPs
• Sediment pond:A temporary pond or several ponds constructed in series to capture turbid water and
provide time to allow sediment to settle out of suspension. After water sufficiently settles or is allowed
contact time with a DWQ approved flocculent, the water may be released.Before using flocculants (e.g,
PAMs), prior permission must be obtained from DWQ.Allowing the water to evaporate if sufficient
holding capacity exists or release to a vegetated filter strip may also be acceptable.Sediment pond or
settling basins can be designed in various sizes to accommodate the flow.The use of the erosion control
basin permitted solely for the construction activities is not acceptable.These basins are designed and
approved for use with a site specific quantity of water; adding the water produced from drilling activities
may overburden these basins.
•Dike, ring,or fence structure:A containment and filtration structure composed of hay bales, silt
fencing, size 57 stone,or other materials to filter sediment from smaller volumes of turbid water. These
materials can be used in various designs and at various scales. The structure can encircle the drill rig or
borehole to filter water or be placed in ditches or trenches downslope from the drill rig. The structure
should have adequate capacity to prevent overflow or by-passing of the filter media unless other filter
structures are in place down-gradient.
• Sediment tank/filter box:A tank structure
constructed from steel drums,modified
dumpsters, wood,or other materials filled with
sand, gravel or other material to trap and filter
slurry water. Portions of the structure after the
filter media may be perforated to allow discharge
to the surface or have a discharge port to pipe
water to other filtration devices.Consideration should be made for moving the structure once it is filled
with sediment. The treatment volume of the structure should also match the anticipated flow volume
during well construction.
• Dewatering containers:These are similar to large ‘frac’tanks (see photo) but serve to filter or separate
slurry water and allow settling of sediment to the bottom of the container. The ‘cleaned’ water can then
be released onsite. ‘Frac’ tanks may also serve to simply store
water (up to 21,000 gallons) onsite until treated or hauled to
another facility for treatment and release.These tanks can be
rented and placed onsite.
•Discharge to sanitary sewer: This may be an option dependent
upon the site and conditions.Consideration should be made in
regard to costs associated with the discharge.You must also
obtain permission from the receiving sewer authority. Please contact the regional Aquifer Protection
Section office prior to discharging.
For additional information, please contact your NCDENR regional office of the Aquifer Protection
Section.Contact information is available online at http://portal.ncdenr.org/web/wq/home/ro