Transcript Status of WWTF Nutrient Reduction Efforts For Narragansett Bay

Status of WWTF Nutrient
Reduction Efforts For
Narragansett Bay
Angelo S. Liberti, Chief
Surface Water Protection
Office of Water Resources
401.222.4700 ext 7225
[email protected]
Surface Water Protection
Major Program Responsibilities
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Designate Water Quality Classifications
Establish Water Quality Standards
Evaluate all waters for Compliance (Integrated Report)
List Waters in violation of WQS (303d list)
Develop Restoration Plans (TMDLs)
Issue Permits Requiring Implementation (RIPDES etc.)
Review Abatement Plans
State Water Quality Standards
• Reflected in DEM Water Quality Regulations
• Subject to EPA approval
• Consistent with national guidance; no less
stringent
• Site specific criteria are allowed
• Criteria can account for naturally occurring
conditions
• Current focus: nutrient criteria and biocriteria
development
Current Estuarine DO Criteria
• Above a seasonal pycnocline, not less than 4.8 mg/l at any
place or time more than once every three years, except as
naturally occurs
• Below the pycnocline, instantaneous values below 4.8 are
acceptable provided:
– not less than 2.9 for any 24 hour period May 1-October 31
– Not less than 1.4 mg/l for more than 1 hour more than twice May
1-October 31
– cumulative exposure to DO less than 4.8 mg/l doesn’t exceed
prescribed values.
Use Attainability Analysis
• Mechanism required under the Clean Water Act to reach a
decision that a specific waterbody will not be able to
achieve its designated uses
• Not widely used in New England
• Key factors in UAAs:
Demonstration of widespread economic harm
UAA Example: Pawtuxet River
• Completed in early 1980’s for the Main
Stem of the Pawtuxet River
• Revisited in response to a February 16,
1988 letter from the Mayors of Cranston
and Warwick and the West Warwick
Council President.
– “ The theoretical water quality required for
this use [propagation of fish] is impossible
to meet …”
– “… take whatever other steps are necessary
to eliminate the need for advanced
wastewater treatment plants along the
Pawtuxet River.”
UAA Example: Pawtuxet River
Water Quality Assessment Process
 TMDLs are not a
prerequisite for
issuance of
discharge permits
Estuarine Waters Listed as
Impaired (DO)
• Providence and Seekonk Rivers
(since 1994)
• Potter Cove (1998)
• Greenwich Bay & Coves (1998)
• Upper Narragansett Bay (2000)
• East &West Passages (2008)
•Palmer River (1992)
•Wickford Harbor (1994)
•Pawcatuck (1994)
•Mt. Hope Bay (1998)
•Greenhill Pond (2002)
2008 Expansion of DO Impairment
• In its Intergrated
Report on statewide
water quality
conditions, DEM
expanded the area in
the mid-bay
designated as impaired
due to low DO.
Current TMDL Schedule
Estuarine DO Impairments
Waterbody
First
listed
Target for
TMDL
Palmer River
1992
2016
Providence and Seekonk Rivers
1994
2016
Wickford Harbor
1994
2012
Pawcatuck River
1994
2010
Mt. Hope Bay
1994
2012
Potter Cove
1998
2016
Greenwich Bay & Coves
1998
2016
Upper Narragansett Bay
2000
2016
Green Hill Pond
2002
2008
West & East Passages
2008
2016
Early Focus: Providence and
Seekonk Rivers
•
“Available data show a marked lowering of dissolved oxygen levels in surface
and bottom waters in the Providence River at least during the warmer months
Reduced oxygen levels at times extend down Bay. (Olsen and Lee 1979)
•
“The lowest oxygen values throughout the channel bottom were recorded on
the August 8, 1980 sampling, those values were 0 to 3 mg/l all the way to
Conimicut Pt.” (Oviatt 1979-1980)
•
SPRAY& SQUIRT Cruises – 7 surveys (high and low tide samples), 3
summer surveys of DO, June and August 1987, September 1989 Ave bottom
oxygen all Providence and Seekonk River Stations: 3 mg/l –4 mg/l
Expanded Data Collection Efforts
• DEM – 1995 1996 Total of 11 High and low tide surveys.
– 1995 extreme variations in oxygen and chlorophyll, periods where
entire area is <4mg/l, bottom waters in significant portions of the
Seekonk and Providence frequently 0-1 mg/l. 1996 mid June-late
September bottom DO rarely above 4 down to Conimicut Point,
typically near 0 down to Sabin Pt.
• Insomniacs – multi-agency, monthly, overnight surveys 1999-2003,
2005 and continuing
• Fixed-Site Monitoring Network Expansion: DEM, in partnership with
NERRS, the NBC and URI-GSO added stations: from 7 to 9 stations
during the summer of 2003; from 9 to 12 summer of 2005; from 12 to
• NOAA- Bay Window – shuttle surveys; 1998-present, monthly baywide transects
Prior Modeling Efforts – Providence &
Seekonk Rivers
•
July -December 1989 – Narragansett Bay Project formed a Water Quality
Model Technical Advisory Group and hired Limno-Tech to provide
recommendations to the group.
•
January 1990 – NBP held a workshop with stakeholders to discuss TAC
recommendations and plan for development of a model to establish an
abatement strategy.
•
1992-Researchers at EPA Lab in Narragansett produced Providence Seekonk
DO and Nitrogen Model (Dettman 1992)
– Collection of additional data to support development of a time dependent
model that includes phytoplankton
•
1992 – NBP hired Limno-Tech to enhance the model produced by Dettman
(include impacts from phytoplankton and time variable predictions)
– Model not designed to capture variability of short term events observed due to
high algal productivity
– Over 50% reduction in Nitrogen needed to produce an observable response
(higher levels for significant response)
– To improve model reliability need, additional data, improved understanding
of advective flow variations and extend southern boundary of the model.
– Reliability in the current screening model is substantial and provides good
indication of the impact of reduced nitrogen loads on phytoplankton levels.
•
DEM developed sampling program to support development of a time variable,
three dimensional hydrodynamic/water quality model –formed TAC, Tetra
Tech was hired to review past modeling efforts and the proposed
sampling/modeling strategy.
•
DEM engaged ASA to developed a linked hydrodynamics and water quality
model. 1997-2001 held TAC meetings regarding model development.
Problems encountered when modeling the interaction between the deep
channel and shallow flanks of these water bodies, the mass transport
component of the model system could not be successfully calibrated and
validated.
Preliminary WWTF Nitrogen
Reduction Plans
• 1998 - RI WWTF
Loading Reduction
Analysis
• 7 WWTFs required to
reduce ammonia agreed
to reduce total N
Current Plan for Managing Nutrients
• Work was already underway
• Greenwich Bay Fish Kill –
August 2003
• Draft Plan for nutrient reductions
(DEM, Feb. 2004)
• Governor’s Commission Report
& Legislation – 2004
• Adoption in law of goal of 50%
reduction in N loadings - 2004
• DEM permits issued – June 2005
Revised WWTF Nitrogen Limits
• 5 mg/l
– UBWPAD
–
–
–
–
Woonsocket
NBC-Fields Pt.
NBC Bucklin Pt.
East Greenwich
•8 mg/l
–
–
–
–
–
No. Attleborough
Attleboro
Grafton
Uxbridge
Northbridge
– (max extent)
–
–
–
–
–
–
East Providence
Cranston
West Warwick
Warwick
Smithfield (10 mg/l)
Burrillville (max extent)
- Warren – anticipated to address impacts to the Palmer River
•
Limits May – October, require operation of treatment to remove N to
max extent possible November-April
Status of Compliance with Revised Permit limits for N
RI WWTFs
Limit
Status
Ave TN (mg/l)
5/07-8/08
Cranston
8 mg/l
Construction comp. –1/2006
8.2
Warwick
8 mg/l
Construction comp. -11/2004
8.0
West Warwick
8 mg/l
Construction comp. -7/2005
9.2 (7.5)*
East
Greenwich
5 mg/l
Construction comp.–3/2006
4.0
East
Providence
8 mg/l
Facilities Plan (FP) under DEM Review
Construction Deadline 9/2012
12.3
NBC- Bucklin
5 mg/l
Initial Construction Comp. 2006
FP Due 4/2009
7.5
NBC -Field Pt
5 mg/l
Design Due 11/2008
13.7
Woonsocket
5 mg/l
Construction Comp. 2002 Agreed to
complete construction for 3 mg/l by 3/2014
6.7
* Excludes May data (19.5, 13 mg/l)
Status of Compliance with Revised Permit limits for N
RI WWTFs (Cont.)
Limit
Status
Ave TN (mg/l)
5/07-8/08
Burrillville
Max
extent
TN Reductions since 2002
10.5 (7.7)*
Smithfield
10 mg/l
Construction comp. -6/2006
8.3
Warren
Anticipated that Warren will
need to reduce N to address
impacts to the Palmer River
17.7
Westerly
Construction comp. 10/03
6.3
* Excludes May data (19.8, 24.0 mg/l)
Status of Compliance with Revised Permit limits for N
MA WWTFs
Upper Blackstone
(UBWPAD)
5 mg/l
EPA issued 8/08; appeals filed.
Attleboro
8 mg/l
EPA issued 6/08; appeals filed
North Attleborough
5 mg/l
EPA issued 2/08; appeals settled
Grafton
5 mg/l
No action to date
Uxbridge
8 mg/l
No action to date
Northbridge
NA
EPA issued 9/06; reduce N to max
extent
Significance of Massachusetts
WWTFs
• Without reductions at MA WWTFs
– Decrease in loading delivered to the Providence
Seekonk River system will change from 59% to
39% below current levels.
– Seekonk River: 57% reduction with full
participation (loading factor is reduced from 23X
to 10X) only 7% (to 21.5X) without reductions
at MA facilities
Nitrogen Reduction Projections
Average Daily May - October Total Nitrogen Load From 11
RI WWTFs (lbs/day)
•Nitrogen removal at 11 RI WWTFs - reduces their summer season nitrogen loading by 65%,
dropping to 48% as WWTF flows reach approved design flows.
16000
Projected Reduction in Seasonal Nitrogen Load From 11 RI WWTFs Impacting Upper
Narragansett Bay.
14000
12000
10000
8000
6000
4000
2000
0
May October
1995-1996
2004
2005
2006
2007
2009
2011
2013
2014
Year
All calculations are based on May-Oct 95-96 WWTF flows. Loadings will increase as WWTF flows
increase to their approved design flows.
2015
Current Status of Load Reduction
Efforts
• 8 - WWTFs have complete upgrades
•
(
2 require additional modifications)
• 0 - Under construction
• 3 – Planning Underway
• NBC Bucklin Point
• Woonsocket
• East Providence
• 1 - Design Underway
• NBC Fields Point
Things on “Management’s Plate”
• What further reductions will be needed and where? “going
to 3 mg/l”
• Establishment of new shellfish closure procedures in
response to CSO tunnel.
• How best to update predictive tools to modify shellfish
closure area procedures in response to sewer overflows and
to develop monitoring strategies.
• How will CSO tunnel operations affect water quality
beyond the control of pathogens?
• Manchester Street Power Station permit renewal
Side helpings…
• Need to better understand what is
happening in Greenwich Bay; e.g.
groundwater inputs.
• Does monitoring need to be modified to
better answer questions about how the
Bay’s ecology is changing?
Comparison of MERL Experiments to
Providence/Seekonk System
Comparison of observed summer loads to the Providence and
Seekonk Rivers with MERL tank levels
100
Merl N - load (mmol m-2 d-1)
32
90
Observed loads
80
DIN daily loadingrate (mmol/m2/day)
Seekonk River
70
60
Area North of Fields Point
50
16
40
Area north of Bullocks Point
30
8
20
Entire Providence- Seekonk River area
4
10
2
1
0
0
5
10
15
20
Tank case ("x")
25
30
35
Allowable Loading Condition
Oxygen Minimum 1981-1983
5
C
Oxygen (mg/l)
4
y = 4.56e-0.0361x
R2 = 0.98
2X
4X
3
1X
2
8X
16 X
1
32 X
0
0
20
40
60
80
2
Nitrogen Load (mmol/m /d)
100
Evaluation of WWTF Load
Reductions
WWTF Name
1
2
3
4
5
6
7
8
9
10
CRANSTON
EAST PROVIDENCE
NARRAGANSETT BAY COMM-BUCKLIN
NARRAGANSETT BAY COMM-FIELDS
WEST WARWICK
WARWICK
WOONSOCKET
UBWPAD
ATTLEBOROUGH
NORTH ATTLEBOROUGH WWTF
Approved
Design Flow
(MGD)
20.2
10.4
31
65
10.5
7.7
16
56
8.6
4.6
Loading Condition Vs. WWTF Load
Reductions
Enrichment levels assuming tributary attenuation
35
30
Seekonk River
Fields Pt
Bullocks Pt
25
Enrichment level
23.2
Entire Area
20
17.7
15
10.0
9.2
10
7.9
5.9
5
4.2
5.2
4.1
3.9
2.6
2.3
1.4
2.0
1.2
0.9
0
no WWTFs
TN = DMR
TN = 5
TN = 3
Flow = 95-96
Flow = 95-96
Flow = Design
Flow = Design
Figure 19: Summary of projected DIN loading rates to selected reaches of the
Providence and Seekonk Rivers under four scenarios.
Loading Condition Vs. Cost
25
Seekonk Reach
Fields Point Reach
Bullocks Point Reach
Loading Condition (X)
20
15
10
BP, FP, 3 , UB, W 5
Others 8
5
Recommended Option
BP, FP, UB, W 5, Others 8
0
0
50
100
150
200
Capital Cost ($M)
250
300
350
400
Anticipated RI WWTF Load
Reductions
Allowable Loading Condition
Average Chlorophyll vs N Load
70
32 X
y = 0.62 x + 6.32
R2 = 0.94
Chlorophyll a (ug/l)
60
50
16 X
40
30
4X
20
8X
2X
10
1X
C
0
0
10
20
30
40
50
60
70
2
Nitrogen Load (mmol/m /d)
80
90
100