Transcript Status of WWTF Nutrient Reduction Efforts For Narragansett Bay

CHRP/Managers Meeting
October 2009
Angelo Liberti, Chief
Surface Water Protection
Office of Water Resources
401.222.4700 ext 7225
[email protected]
NBC CSO Project
Phase I tunnel - operational Nov 2008
•Post storm monitoring
•Re-assess Rainfall Closure Criteria
Phase II - preliminary design completed
Current Plan for Managing Nutrients From
WWTF
• 50% Reduction from RI
WWTFs
– DEM permits issued – June 2005
• Comparable reductions from
MA WWTFs
Revised WWTF Nitrogen Limits
• 5 mg/l
– UBWPAD
– Woonsocket
• (3 mg/l)
– 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
Current Status of Load Reduction
Efforts
• 8 - WWTFs have complete upgrades
• (2 require additional modifications)
• 1 - Under construction
• NBC Fields Point (completion by 12/31/2013)
• 1 – Planning Underway
• Woonsocket (Plan was due 8/09, construction by 3/2014)
• 2 - Design Underway
• NBC Bucklin Point
• East Providence (due 6/01/10, construction by 9/2012
Approximately 30% reduction in RI WWTF load
achieved in 2005. Next significant reduction
May 2014
Status of Compliance with Revised Permit limits for N
MA WWTFs
North Attleborough
8 mg/l
EPA issued 2/08; appeals settled
(complete construction late 2012)
Attleboro
8 mg/l
EPA issued 6/08; Permit upheld
on appeal. EAB decision issued
9/15/09.
Upper Blackstone
(UBWPAD)
5 mg/l
EPA issued 8/08; appeals filed.
Oral arguments before EAB
10/29/09
Grafton
8 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
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. Additional
modifications to achieve TP = 0.1 mg/l and
consistently achieve TN May-Oct complete
construction by 3/31/2013
8.2
Warwick
8 mg/l
Construction comp. -11/2004 Additional
modifications to achieve TP = 0.1 mg/l and
consistently achieve TN May-Oct
8.0
West Warwick
8 mg/l
Construction comp. -7/2005. Additional
modifications to achieve TP = 0.1 mg/l
9.2 (7.5)*
East Greenwich
5 mg/l
Construction comp.–3/2006
4.0
East Providence
8 mg/l
Final Design due 6/01/10
Construction Deadline 9/2012
12.3
NBC- Bucklin
5 mg/l
Initial Construction Complete 2006
FP approval 10/09, NBC requested 1year 5
months for design.
7.5
* 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
NBC -Field Pt
5 mg/l
Design Approved 09, Complete
Construction 12/31/2013
13.7
Woonsocket
5 mg/l
Construction Comp. 2002 Agreed
to complete construction for 3
mg/l by 3/2014
6.7
Burrillville
Max
extent
TN Reductions since 2002
10.5 (7.7)*
Smithfield
10 mg/l
Construction comp. -6/2006.
Additional changes to
consistently meet TP April-Oct
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
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
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