HomeMy WebLinkAboutAppx C 10-04766-065 WQMP 2015 02 02
WATER QUALITY MONITORING PLAN
BLACK RIVER PUMP STATION
SEDIMENT REMOVAL PROJECT
Department of Natural Resources and Parks
Water and Land Resources Division
Note:
Some pages in this document have been purposely skipped or blank pages inserted so that this
document will copy correctly when duplexed.
WATER QUALITY MONITORING PLAN
BLACK RIVER PUMP STATION
SEDIMENT REMOVAL PROJECT
Prepared for
Department of Natural Resources and Parks
Water and Land Resources Division
King Street Center – DNRP
201 South Jackson Street, Room 700
Seattle, Washington 98104-3855
by
Herrera Environmental Consultants, Inc.
2200 Sixth Avenue, Suite 1100
Seattle, Washington 98121
Telephone: 206.441.9080
February 2, 2015
Prepared by:
Peter Jowise, Herrera Environmental Consultants, Inc.
For comments or questions contact:
Peter Jowise, 206.441.9080, ext. 8220
Alternate Formats Available
206.296.7380 TTY Relay: 711
CONTENTS
1. Introduction ............................................................................................ 1
1.1. Purpose ............................................................................................ 4
1.2. Project Description .............................................................................. 5
2. Monitoring Plan ........................................................................................ 7
2.1. Monitoring Strategy .............................................................................. 7
2.2. Applicable and Relevant Water Quality Standards .......................................... 8
2.2.1. Points of Compliance ............................................................... 8
2.2.2. Specific Criteria ..................................................................... 8
2.3. Water Quality Monitoring Locations ........................................................... 9
3. Water Quality Monitoring Procedures ............................................................. 11
3.1. Sampling Methods ............................................................................... 11
3.2. Water Quality Monitoring Feedback and Response......................................... 11
3.3. Documentation .................................................................................. 12
A PPENDICES
Appendix A Field Form: Daily Water Quality Monitoring Data
i
pj 10-04766-065 wqmp brps sediment removal project.docx
TABLES
Daily Water Quality Monitoring Data Black River Pump Station Sediment Removal
Project ..................................................................................................... A-1
FIGURES
Figure 1. Project Vicinity Map for the Black River Pump Station Sediment Removal
Project, Renton, Washington. ................................................................ 2
Figure 2. Black River Pump Station Site Map, Renton, Washington. ............................... 3
Figure 3. Compliance Areas at the Black River Pump Station Site Map, Renton,
Washington. .................................................................................... 10
ii
pj 10-04766-065 wqmp brps sediment removal project.docx
1. I NTRODUCTION
This Water Quality Monitoring Plan (WQMP) was prepared to describe monitoring requirements
during removal of sediment from the Black River, located in Renton, Washington. The King
County Water and Land Resources Division (KCWLRD) operates the Black River Pump Station
(BRPS) to provide flood control protection for the lower Green River Valley. The BRPS is
situated on the Black River about 1,700 feet upstream from its confluence with the Green
River (Figure 1). The Black River historically was part of the Cedar River drainage system, but
currently is considered the downstream reach of Springbrook Creek, which has an estimated
mainstem length of 12 miles, draining approximately 15,763 acres (24.7 square miles).
The pump station consists of a concrete dam that spans the Black River channel, with eight
pumps to convey flow from the forebay behind the dam to the downstream Black River
channel. Plant pumps can handle Black River flow up to an estimated 2,945 cubic feet per
second (cfs) capacity, which exceeds a 1 percent flood condition. In order to protect
properties downstream, the station is not run at full capacity when the Green River is near
levee capacity; excess inflow is held in channel storage behind the dam. Flood control is
accomplished by starting the large pumps at an early stage of a storm. During normal, non-
storm flow conditions, only pump P-1 is used to regulate discharge past the dam, typically
cycling on and off for a few hours a day (using an automated stage control system). Fish
migration facilities are also included for upstream and downstream fish passage around the
pump station. Construction will be conducted during the July and August fish window when
fish passage facilities are not run.
The dam is designed to prevent Green River backflow into the Black River and its tributaries;
it has freeboard over best available estimates of 1 percent annual exceedance flood
conditions on the Green. All flow past the dam is pumped toward the Green. Water levels
downstream of the dam range from -4.0 to +21.5 feet mean sea level (MSL), depending on
tidal conditions and water level of the Green River. Water surface elevations upstream of the
dam are normally held in the range of 0.0 to +2.0 feet MSL. Flow rates below the dam are not
measured, but vary at any particular time based on a combination of BRPS pumping, Green
River flow, and tidal fluctuation. As such, it is difficult to predict the flow rate of water
moving from the dam toward the Green River at any point in time. The monthly average flow
rates measured at a stream gauge located on Springbrook Creek approximately 1 mile
upstream of the BRPS for July and August over 4 years of available records are 13.1 and
7.8 cfs, respectively.
Sediment that has accumulated upstream of the pump station since its construction in the
1970s is now an operational concern for the facility. The KCWLRD proposes to remove about
2,900 cubic yards of sediment from the river channel, extending about 100 feet upstream of
the pump station (Figure 2). The sediment removal area includes a concrete forebay apron
(an approximately 1-foot-thick concrete slab covering the 165-foot width between the pump
station retaining walls and extending 75 feet upstream of the pumping bays), the narrow area
between the dam trash grates and pump bays, and east (upstream) of the apron up to existing
grade. The thickness of sediment to be removed varies from 7.0 to 15.5 feet. Sediment will
be removed by dewatering the work area behind a cofferdam and excavating directly from
the riverbed.
February 2015
Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project 1
K:\Projects\Y2010\10-04766-065\Project\Water_Quality_Monitoring_Plan\vicinity_map_landscape.mxd (1/30/2015)
ESRI, Aerial (2011)
Figure 1.Project Vicinity Map for the Black River Pump Station Sediment Removal Project, Renton, Washington.
MONSTER RD SW
RD SWMONSTERPump StationD
u
w
a
m
i
s
h
R
i
v
e
r
Spri
n
g
brookCreekG
re
e
n
R
iv
er
B l a c k River
Source: Esri, DigitalGlobe, GeoEye, i-cubed, Earthstar Geographics,CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP,swisstopo, and the GIS User Community
0 400 800200Feet
P A C I F I CO C E A N
WASHINGTON
BRITISH COLUMBIA
Index
Forks
TacomaShelton
Seattle
Everett
Chehalis
Cle Elum
Bremerton
Darrington
Bellingham
Leavenworth
Ocean Shores
Port Angeles
Mount Vernon
Olympia
Legend
Railroad
K:\Projects\Y2010\10-04766-065\Project\Water_Quality_Monitoring_Plan\site_plan.mxd (1/23/2015)
0 100 20050Feet
Legend
Area of sediment removal
Pump Station discharge point
Bing, Aerial (2014)
Figure 2. Black River Pump Station Site Map,Renton, Washington.
Analytical test results on sediment samples indicate arsenic, cadmium, and total petroleum
hydrocarbons (TPH) concentrations that exceed the Model Toxics Control Act (MTCA)
Method A or B cleanup levels for unrestricted land use (WAC 173-340). In addition, sediment
exceeds freshwater sediment quality criteria (WAC 173-204) for TPH, bis(2-ethylhexyl)
phthalate, total polychlorinated biphenyls (PCBs), arsenic, cadmium, and nickel. As a result,
the removal method will include provisions to control the release of contaminated sediment.
1.1. Purpose
The purpose of this WQMP is to:
• Provide a methodology for assessment of impacts to surface water that may result
from in-water activities.
• Define the protocol for providing real-time feedback to the contractor so that all
construction activities remain in compliance with water quality criteria.
The WQMP describes protocols for routine monitoring, with both specific and general
procedures identified for corrective actions. It is important that the user conduct additional
monitoring to demonstrate that corrective actions have been successful, as necessary. Any
non-routine, additional monitoring shall be documented in field notebooks and/or field data
sheets.
The objectives of this plan are to:
• Define the process for monitoring water quality during in-water construction activities
including:
o Installation and removal of temporary flow diversion structures and equipment.
o Isolation of the dredge area within the Black River channel.
• Provide a methodology to:
o Verify that water quality conditions are within the limits specified in all applicable
state and federal laws and permits.
o Identify whether water quality problems are occurring as a result of in-water
project activities.
• Assist field monitors in the determination of when to modify in-water act ivies to
ensure protection of the environment if exceedances of water quality criteria occur.
• Define communication and response protocol in the event of an exceedance of water
quality criteria.
This WQMP is specific to in-water activities; control of upland water discharges will be
addressed by separate plans. The contractor will be required to conduct all operations in
compliance with these performance standards.
February 2015
4 Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project
1.2. Project Description
There are three construction elements that have the potential to affect Black River water
quality:
• Isolating the in-water work area with turbidity curtains, temporary flow diversion
structures, or other best management practices (BMPs).
• Dredging sediment and stockpiling it adjacent to the river.
• Removing in-water BMPs.
Excavation will involve isolating the sediment removal area from the river by constructing a
temporary flow diversion structure (e.g., cofferdam) spanning the entire width of the river,
installing temporary pumps and piping to divert the river, and dewatering the sediment
removal area. The work area will be partially dewatered using the pump station pumps until
water levels are too low or turbidity levels are too high, at which point portable pumps will
be used to remove the remaining water. Sediment will then be dredged using conventional
excavation equipment placed into the dewatered area between the cofferdam and existing
pump station structure by a crane.
During excavation, portable pumps will remain on-site to remove water that may seep past
the cofferdam. Water will be pumped downstream of the pump station, unless it is too turbid
to meet State water quality standards. If the pumped water is too turbid, it will be pumped
directly to the on-site facility used to treat decant water. River flow past the dam will be
controlled by regulating pump rates, as well as relying on the ability of the cofferdam to hold
water in the upstream storage basin.
Hydraulic dredging (using suction pumps to remove sediment and entrained water) may also
be used to remove sediments within the pump bay area behind the trash racks due to
difficulty accessing that area.
February 2015
Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project 5
2. M ONITORING PLAN
2.1. Monitoring Strategy
The dredging design aims to limit the potential for release of contaminated water into the
environment. Project components and associated BMPs are designed to ensure that the
majority of the in-water activities will not disturb submerged sediment or the water column.
The primary activities expected to disturb sediment, in work order, include:
• Installation of turbidity curtains upstream of the contractor-installed river bypass
structure and downstream of the BRPS dam
• Installation and operation of the upstream river bypass system (vault, channel
modification, pumps, and pipe)
• Installation of the cofferdam
• Dewatering of the work area between the BRPS dam and the cofferdam
• Ongoing dewatering of seepage in the work area
• Allowing water to re-enter the work area following sediment removal
• Removal of the cofferdam
• Removal of the river flow bypass system
• Removal of turbidity curtains
Once the river bypass system is operating, most of the river flow will not reach the work area.
With the bypass intake positioned far enough upstream of the work, any highly turbid water
associated with seepage into the dredging area can either be judiciously mixed with bypass
river water or diverted to the upland treatment system associated with sediment dewatering.
The bypass system will be operated to minimize entrainment of sediment.
Black River water upstream of the work area has a potential to be impacted by the work only
when the river is backed up behind the dam. The monitoring plan outlined below will be
tailored to the operating conditions in play at any particular time. River flow conditions,
regulated either by the BRPS pumps or the bypass system operations, will be documented for
each monitoring event such that the proper upstream or downstream point of compliance is
addressed.
Water quality monitoring of temperature, dissolved oxygen (DO), turbidity, and pH will take
place during in-water activities, as described below.
Field monitoring will occur at least twice daily during in-water activities. If the work day is
longer than 8 hours, monitoring will occur at least once every 4 hours.
February 2015
Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project 7
2.2. Applicable and Relevant Water Quality Standards
During construction, water quality criteria as defined within WAC 173-201A needs to be
attained at specified points of compliance.
2.2.1. Points of Compliance
Based on typical summer flows of around 10 cfs, the points of compliance will be
conservatively set at a distance of 100 feet, per WAC 173-201A-200. The specific upstream or
downstream point of compliance location will depend on the control of flow during
performance of the specific activity:
• When pumping water past the dam, the point of compliance will be 100 feet
downstream of the discharge point.
• When no pumping takes place, the point of compliance will be 100 feet upstream of
the work being conducted (e.g., river bypass system, cofferdam), which defines the
work boundary.
The only exception to this will apply to installation and removal of BMP features (e.g.,
turbidity curtains) either downstream of the pump station or upstream of the bypass system,
when the point of compliance will be extended 100 feet from these activities.
2.2.2. Specific Criteria
Specific criteria are based on the Aquatic Life Use designation of Salmonid Spawning, Rearing,
and Migration for the Black River (WAC 173-201A-602). Criteria associated with this
designation are specified in WAC 173-201A-200 and summarized in the following sections.
2.2.2.1. Temperature
At the point of compliance, the highest 7-day average of the daily maximum temperatures
(7-DADMax) shall be 17.5 degrees Celsius (°C). If the background temperature exceeds the
criterion (or is within 0.3 °C of the criterion) due to natural conditions, then human actions
may not cause the 7-DADMax temperature to increase more than 0.3 °C (0.54 °F). If the
background temperature is cooler than the criterion, the allowable rate of warming up to,
but not exceeding, the numeric criterion from the project is restricted to:
• Incremental temperature increases resulting from construction activities must not, at
any time, exceed 28/(T+7) as measured at the edge of a mixing zone boundary (where
“T” represents the background temperature in °C)
• Incremental temperature increases resulting from the combined effect of all nonpoint
source activities in the water body must not, at any time, exceed 2.8 °C.
The incremental temperature increase is measured as the difference between background
and downstream point of compliance conditions. Background temperature measurements
should be taken from well-mixed portions of rivers and streams to represent the dominant
aquatic habitat of the area. Samples should not be taken from shallow stagnant backwater
areas, within isolated thermal refuses, at the surface, or at the water’s edge.
February 2015
8 Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project
2.2.2.2. Dissolved Oxygen
At the point of compliance, DO shall exceed the standard of 8.0 milligrams per liter (mg/L). If
background DO is lower than this criterion (or within 0.2 mg/L of the criterion) due to natural
conditions, then the background condition minus 0.2 mg/L will replace the criterion.
2.2.2.3. Turbidity
Turbidity shall not exceed 5 nephelometric turbidity units (NTU) above background when
background turbidity is 50 NTU or less. If background turbidity is greater than 50 NTU,
turbidity shall not be increased more than 10 percent above background.
2.2.2.4. pH
At the point of compliance, pH must be within the range of 6.5 to 8.5 with a human-caused
variation within the above range of less than 0.5 units (between background and downstream
point of compliance conditions).
2.3. Water Quality Monitoring Locations
Monitoring locations include compliance point sites and a background site that are monitored
on a daily basis during construction activities. Approximate monitoring locations are shown on
Figure 3 and will include the following sites:
• Background (BG) – along a transect located approximate 200 feet upstream from the
river bypass structure and downstream of the last tributary to the Black River,
Springbrook Creek (shown in Figure 3 as relative to the BRPS dam). Samples will be
collected for monitoring from a depth of 0.5 meter from the surface during in-water
construction activities. If total depth of water is less than 1.5 meters, samples will be
collected from mid-depth.
• Downstream Dam (DD) – along a transect located 100 feet downstream of the pump
discharge location (shown in Figure 3 as relative to the BRPS dam). Samples will be
collected for monitoring from a depth of 0.5 meter from the surface and from 1 meter
above the river bottom when water is being discharged below the dam. If total depth
of water is less than 1.5 meters, samples will be collected from mid-depth.
• Upstream Dam (UD) – along a transect located 100 feet upstream of the in-water work
at any particular time, which will vary between the turbidity curtain, river bypass
structure, and cofferdam (shown in Figure 3 as relative to an estimated cofferdam
location). Samples will be collected for monitoring from a depth of 0.5 meter from the
surface during installation and removal of the structure. If total depth of water is less
than 1.5 meters, samples will be collected from mid-depth.
• Continuous Turbidity Monitoring – both dewatering discharge and river bypass
discharge water will be continuously monitored, with data recorded at 10-minute
intervals (if both flows are combined, only one meter is necessary). These data will be
used to determine effectiveness of the treatment system and whether the bypass
system is entraining sediment, indicating the need to alter operations. Also, due to the
complicated flow regime below the BRPS dam, turbidity may be naturally elevated
downstream of the DD location. Discharge turbidity measurements can be used to
demonstrate that upstream work activities are either not responsible for the
exceedance or that work activities need to be changed to achieve compliance.
February 2015
Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project 9
K:\Projects\Y2010\10-04766-065\Project\Water_Quality_Monitoring_Plan\compliance_plan.mxd (1/23/2015)
0 100 20050Feet
Legend
Area of sediment removal
Pump Station discharge point
Point of compliance - downstream (approximate)
Point of compliance - upstream (approximate)
Background
Bing, Aerial (2014)
Figure 3. Compliance Areas at the BlackRiver Pump Station Site Map, Renton, Washington.
Note: Actual points of compliance to be determined by specific activity
3. WATER Q UALITY M ONITORING PROCEDURES
Water quality monitoring involves field measurement of the conventional parameters
turbidity, DO, pH, and temperature. Field monitoring at compliance and background locations
will occur at regular intervals (i.e., a minimum of every 4 hours) throughout the in-water
work period. Readings at each sample location will be taken at two depths: 0.5 meter below
the surface and from 1 meter above the river bottom. For comparison of background to
compliance sites, the deeper readings will be compared between sites, and the shallower
readings will be compared between sites.
3.1. Sampling Methods
Field monitoring will be conducted with handheld water quality instruments, such as a
multimeter, that measure all parameters or a combination of meters that measure individual
parameters. Readings may be made in situ by lowering the meter probe to the desired depth,
or may be taken from samples collected using a water sampler, such as a Van Dorn bottle.
The readings will be recorded on field data sheets or in the field log book. The handheld
water quality probe will be calibrated daily pursuant to the manufacturer’s guidelines, and
calibration data will be recorded in a field data sheet or in the field log book.
The monitoring locations will be accessed using a vessel at the deepest part of the river
channel, determined by sounding or using a depth finder (locations indicated in Figure 3 are
representative transects along which the deepest point should be found, depending on the
specific location of in-water work being performed). The meter probe will be allowed to
stabilize prior to recording the readings. Monitoring will be conducted at upstream (BG) to
downstream (UD or DD) locations sequentially, within as short a time as possible.
3.2. Water Quality Monitoring Feedback and Response
If field measurements exceed applicable criteria, in-water work will be halted or slowed, and
the Resident Engineer (RE) will be notified. At the discretion of the RE, work practices will be
adjusted, and the source will be investigated. Once a suspected cause has been identified,
alterations to the work methods have been made, and any turbidity plumes associated with
the in-water work have dissipated, in-water activities may resume and return to a normal
working pace.
Field monitoring will be repeated within 1 hour from the time the modified activities begin. If
the results of this monitoring show compliance, monitoring will continue at the 4-hour
minimum frequency. If the results again show non-compliance, in-water activities will be
halted and the RE will determine the appropriate actions. Reporting requirements to Ecology
will be established in the 401 Water Quality Certification.
February 2015
Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project 11
3.3. Documentation
Appendix A provides a field form to be used each day to document monitoring results. Entries
shall be made for both shallow and deep measurements at each location. If water depth is
less than 1 meter, only one sample will be collected. Daily reports shall be submitted to the
RE each day for both point of compliance monitoring and continuous turbidity monitoring.
February 2015
12 Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project
APPENDIX A
Field Form: Daily Water Quality
Monitoring Data
Daily Water Quality Monitoring Data Black River Pump Station Sediment Removal Project
Date:
Time
Station-
depth
Turbidity
(NTU)
Temperature
(°C)
Dissolved
Oxygen
(mg/L) pH Notes Initials BG-S
BG-D
DD-S
DD-D
UD-S
UD-D
BG – DD or UD*
BG-S
BG-D
DD-S
DD-D
UD-S
UD-D
BG – DD or UD*
BG-S
BG-D
DD-S
DD-D
UD-S
UD-D
BG – DD or UD*
BG-S
BG-D
DD-S
DD-D
UD-S
UD-D
BG – DD or UD*
Use shallow (S) designation and not the deep (D) designation for single monitoring depth, if necessary.
*Compare to criteria in Section 2.2.
February 2015
Water Quality Monitoring Plan—Black River Pump Station Sediment Removal Project A-1