Wastewater Management Division Montly ...
DATE:
September 22,2016
TO:
Public Utilities Committee
VIA:
Nick Schiavo, Public Utilities Department and Water Division Director
FROM:
Shannon Jones, Wastewater Management Division
SUBJECT:
Wastewater Management Division (WWM) Informational Update
Director-~
Pennitting WWM staff submitted a renewal application for Discharge Pennit DP-135 for solids disposal on March 31, 2016. On April 5, 2016 the application was detennined to be administratively complete. Public Notice of application was posted in the New Mexican on May 30, 2016. WWM Staff met with the New Mexico Environmental Department (NMED) on September 6, 2016 where additional information was requested. Staff submitted requested information on September 14, 2016 and expects to receive a draft permit within the next two months. Major Projects WWM staff and HDR have begun work on the design of the two (2) new Anaerobic Digesters with a target date tor design completion in November 2016 with construction begim1ing in 2017. On September 15,2016, WWM statfreceived 60% Design and Draft Specifications for review. Statf has released a Request tor Proposal (RFP) for a Nutrient Removal Study. The proposals will be received on October 13,2016. It is anticipated the study will begin in early 2017. Recently there has been much discussion around the capacity of the City's wastewater collection and treatment systems. These discussions have been driven by requests t()r sewer service outside the presumptive city limits. The Wastewater Treatment Facility has several treatment processes that are designed to remove a pat1icular partial type or specific pollutant. The preliminary treatment serves to remove inorganics such as rocks, plastics and paper. The primary treatment removes settable solids and grease. The secondary treatment is a biological process targeting Total Suspended Solids (TSS) as we11 as ammonia, nitrates/nitrites and Carbonaceous Biochemical Oxygen Demand (CBOD).
2
The tertiary treatment filters out remaining particles greater than 10 microns (J.tm) (A grain of beach sand can range from 100 to 2000 J.lm and a mold spore is 10 to 30 J.tm). The ultra violet disinfection neutralizes any remaining microorganisms to control regrowth after treatment. The hydraulic capacity of the facility is determined by the surface area and detention time of the individual processes which determine how much water can pass through the facility without overflowing. Because wastewater flows are not linear and fluctuates, a peaking factor must be accounted for. So the true capacity will include the ability to absorb the peak flows. The capacity for the Paseo Real Wastewater Treatment Facility is defined as 13 million gallons per day (MOD). Consideration must be given to the material that is removed by the treatment process. The facility must have the ability to move and process the solids and contaminates removed through treatment. Solids handling is a separate process that has just as many regulatory requirements as the water leaving the plant through the outfall. Currently the treatment facility process about 49,000 gallons per day of biosolids. The solids are sent to anaerobic digesters to be stabilized into a class B biosolid. Once stabilized, the sludge is either mixed with green waste to produce a Class A soil conditioner compost or land applied in a sludge disposal field under a NMED Discharge permit (DP-135). The WWM is currently working to construct two (2) new anaerobic digesters at an estimated cost of $5.5 million. The two (2) new digesters will have the ability to treat 65,000 gallons per day ofbiosolids and allow the facility to rehabilitate the two (2) existing digesters within the next three (3) years as identified in the 5-year CIP. The National Pollutant Discharge Elimination System (NPDES) Permit is the document issued by the Environmental Protection Agency (EPA) allowing the facility to discharge treated effluent into the lower segment of the Santa Fe River and sets regulatory limits for pollutants that remain in the treated effluent. Typically this is regulated in two ways. The first way is based upon a loading (ie lbs/day) and the second on a concentration (ie mg/L). Below (Tablet) are some of the City of Santa Fe's limits under the current NPDES permit that became effective September I, 2016. Tabler Pollutant
Mass30-Day Avelbs/day
CBOD TSS CBOD % removal TSS % removal E. Coli Total Phosphorus Total Nitrogen Dissolved Oxygen TRC
709* 2127* >85% >85% 108** 231**
Concentration dayAvemg/L
n 7-day Ave mg/L
10 30
45
126 3.1 6.9
N/A N/A
Minimum 5 mg/1
Daily
Concentration Dally Max
15
410 Report Report 11 ug/L
3
In Table1 the pennit limits identified with (*) are pem1it limits established by Total Maximum Daily Loads (TMDLs) for the Santa Fe River. The Loading limits for these were determined based on a design flow of 8.5 MGD. Pcnnit limits identified with (**)are pennit limits that were detennined by utilizing the 95 111 percentile of data collected during the last three years. Straightline math calculations between cmTent Loadings/Concentrations and Flow are as follows; CBOD TSS Total Phosphorus Total Nitrogen
709 lbs = 10 mg/L * 8.345 * 8.5 MGD 2,127lbs = 30 mg/L * 8.345 * 8.5 MGD 108 lbs = 3.1 mg/L * 8.345 * 4.2 MGD 231 lbs = 6.9 mg/L * 8.345 * 4.0 MGD
The facility itself can only control the concentrations (mg/L) and the flow (MGD) leaving the outfall. The equations above exhibit the conditions for maximum loadings. Table2, below depicts how the control of concentrations can allow for an increase of flow without an increase in loading. For example with CBOD the concentration is half the allowable limit, therefore the flow can theoretically be doubled as long as the current water quality can be maintained. Table2 2015 Effluent Maximum Values
CBOD TSS
709 lbs
=
16.7
MGD
*
5.1
mg/L
*
8.345
39.2
MGD
*
6.5
mg/L
*
8.345
2,127
lbs
=
Total Phosphorus
108
lbs
=
3.4
MGD
*
3.8
mg/L
*
8.345
Total Nitrogen
231
lbs
=
3.7
MGD
*
7.4
mg/L
*
8.345
As can be seen in the Table2, CBOD and TSS are currently removed to a very low level. This has been accomplished because the City invested $5 million in 1996 and an additional $1.3 million in 20 I 0 to construct and rehabilitate the tertiary treatment process. In 2017 the Wastewater Management Division will complete a comprehensive nutrient study of the facility and the segment of the Santa Fe River affected by the outfall. It is expected that this study will detennine reasonable treatment goals for each process in regards to nutrient removal. In addition the study will detennine realistic expectations for the next NPDES pe1mit renewal. The study will also look at the oxygen uptake rate in the aeration process which will provide valuable intonnation as the Division begins the major rehabilitation of the aeration system starting in fiscal year 17/18 (as identified in the 5-year CIP). In order to comply with the cuiTent NPDES pennit assuming a 5.6 MGD flow, within the next three years the facility will need to consistently remove Total Phosphorus to below 2.3 mg/L and Total Nitrogen below 4.9 mg/L as monthly averages. In order tor the facility to treat the design flow of 13 MGD at the current pennit loading limits, Total Phosphorus would need to consistently be removed to Jess than I mg/L and Total Nitrogen would need to be removed to less than 2.2 mg/L as monthly averages.
4
In Summary, the new limits for Total Nitrogen and Total Phosphorus have been exceeded on at least one occasion in 2015 and in 2016. Staff believes that the new NPDES permit limits can be met by increasing nutrient monitoring, which will provide a more accurate representation of nutrient levels in the effluent, and by optimizing the current treatment processes to treat the current flow into the treatment facility. As more effluent is treated, the likeliness of more exceedance will also increase. Ultimately a treatment train for nutrient removal wiJI need to be added to the facility to treat future flows and future, more stringent, permit requirements.
ATTACHMENTS:
o 2016 Wastewater Treatment Facility Masterplan Treatment Process Capacity Numbers o 2015/2016 SummaryofWaterQuality Plant Data
5
2016 Wastewater Treatment Facility Masterplan Capacity Numbers 35
c
~
~
30
27
s:::::
>
·-....,u
25
• Loading Based Capacity
n:l
c..
n:l
u
II) II)
20
17.8
(U
u 0 s...
D Hydraulically Based Capacity
15
0.
...., s:::::
(U
E ...., m (U
10
~
5
Wastewater Treatment Facility Processes
6
CITY OF SANTA FE WASTEWATER TREATMENT FACILITY 2015 Plant Data 2015 Annual Summary
INFLUENT EFFLUENT FLOW FLOW MOD MOD
1,976 5.42 6.75
Sum Daily Avg Daily Max
t=~r 28 57
EFFLUENT BIOLOGIAL OXYGEN DEMAND MOIL 23,4540bs) 1.80 5.08
EFFLUENT TOTAL SUSPENDED SOLIDS MG/L 20,848 (lbs) 1.60 6.50
TOTAL NITROGEN LBS/DAY 30/DAY AVERAGE 60,137 164.76 289.50
TOTAL PHOSPHORUS LBS/DAY 30/DAY AVERAGE 14,381 39.4 102
TREATED EFFLUENT REUSE MILLION GALLONS 342 0.94 3.22
Through August 2016 Plant Data 2016 Accumulative Summary
Sum Daily Avg Daily Max
INFLUENT EFFLUENT FLOW FLOW MGD MOD
i
1,258 5.18 6.21
922 3.78 6.61
EFFLUENT BIOLOGIAL OXYGEN DEMAND MG/L 16,619 2.16 4.78
EFFLUENT TOTAL SUSPENDED SOLIDS MG/L 19,543 2.54 6.0
TOTAL NITROGEN LBS/DAY 30/DAY AVERAGE 36,207 149 306.7
TOTAL PHOSPHORUS LBS/DAY 30/DAY AVERAGE 12,709 52.3 302
TREATED EFFLUENT REUSE MILLION GALLONS 402 1.65 4.91
7
September 22,2016
TO:
Public Utilities Committee
VIA:
Nick Schiavo, Public Utilities Department and Water Division Director
FROM:
Shannon Jones, Wastewater Management Division
SUBJECT:
Wastewater Management Division (WWM) Informational Update
Director-~
Pennitting WWM staff submitted a renewal application for Discharge Pennit DP-135 for solids disposal on March 31, 2016. On April 5, 2016 the application was detennined to be administratively complete. Public Notice of application was posted in the New Mexican on May 30, 2016. WWM Staff met with the New Mexico Environmental Department (NMED) on September 6, 2016 where additional information was requested. Staff submitted requested information on September 14, 2016 and expects to receive a draft permit within the next two months. Major Projects WWM staff and HDR have begun work on the design of the two (2) new Anaerobic Digesters with a target date tor design completion in November 2016 with construction begim1ing in 2017. On September 15,2016, WWM statfreceived 60% Design and Draft Specifications for review. Statf has released a Request tor Proposal (RFP) for a Nutrient Removal Study. The proposals will be received on October 13,2016. It is anticipated the study will begin in early 2017. Recently there has been much discussion around the capacity of the City's wastewater collection and treatment systems. These discussions have been driven by requests t()r sewer service outside the presumptive city limits. The Wastewater Treatment Facility has several treatment processes that are designed to remove a pat1icular partial type or specific pollutant. The preliminary treatment serves to remove inorganics such as rocks, plastics and paper. The primary treatment removes settable solids and grease. The secondary treatment is a biological process targeting Total Suspended Solids (TSS) as we11 as ammonia, nitrates/nitrites and Carbonaceous Biochemical Oxygen Demand (CBOD).
2
The tertiary treatment filters out remaining particles greater than 10 microns (J.tm) (A grain of beach sand can range from 100 to 2000 J.lm and a mold spore is 10 to 30 J.tm). The ultra violet disinfection neutralizes any remaining microorganisms to control regrowth after treatment. The hydraulic capacity of the facility is determined by the surface area and detention time of the individual processes which determine how much water can pass through the facility without overflowing. Because wastewater flows are not linear and fluctuates, a peaking factor must be accounted for. So the true capacity will include the ability to absorb the peak flows. The capacity for the Paseo Real Wastewater Treatment Facility is defined as 13 million gallons per day (MOD). Consideration must be given to the material that is removed by the treatment process. The facility must have the ability to move and process the solids and contaminates removed through treatment. Solids handling is a separate process that has just as many regulatory requirements as the water leaving the plant through the outfall. Currently the treatment facility process about 49,000 gallons per day of biosolids. The solids are sent to anaerobic digesters to be stabilized into a class B biosolid. Once stabilized, the sludge is either mixed with green waste to produce a Class A soil conditioner compost or land applied in a sludge disposal field under a NMED Discharge permit (DP-135). The WWM is currently working to construct two (2) new anaerobic digesters at an estimated cost of $5.5 million. The two (2) new digesters will have the ability to treat 65,000 gallons per day ofbiosolids and allow the facility to rehabilitate the two (2) existing digesters within the next three (3) years as identified in the 5-year CIP. The National Pollutant Discharge Elimination System (NPDES) Permit is the document issued by the Environmental Protection Agency (EPA) allowing the facility to discharge treated effluent into the lower segment of the Santa Fe River and sets regulatory limits for pollutants that remain in the treated effluent. Typically this is regulated in two ways. The first way is based upon a loading (ie lbs/day) and the second on a concentration (ie mg/L). Below (Tablet) are some of the City of Santa Fe's limits under the current NPDES permit that became effective September I, 2016. Tabler Pollutant
Mass30-Day Avelbs/day
CBOD TSS CBOD % removal TSS % removal E. Coli Total Phosphorus Total Nitrogen Dissolved Oxygen TRC
709* 2127* >85% >85% 108** 231**
Concentration dayAvemg/L
n 7-day Ave mg/L
10 30
45
126 3.1 6.9
N/A N/A
Minimum 5 mg/1
Daily
Concentration Dally Max
15
410 Report Report 11 ug/L
3
In Table1 the pennit limits identified with (*) are pem1it limits established by Total Maximum Daily Loads (TMDLs) for the Santa Fe River. The Loading limits for these were determined based on a design flow of 8.5 MGD. Pcnnit limits identified with (**)are pennit limits that were detennined by utilizing the 95 111 percentile of data collected during the last three years. Straightline math calculations between cmTent Loadings/Concentrations and Flow are as follows; CBOD TSS Total Phosphorus Total Nitrogen
709 lbs = 10 mg/L * 8.345 * 8.5 MGD 2,127lbs = 30 mg/L * 8.345 * 8.5 MGD 108 lbs = 3.1 mg/L * 8.345 * 4.2 MGD 231 lbs = 6.9 mg/L * 8.345 * 4.0 MGD
The facility itself can only control the concentrations (mg/L) and the flow (MGD) leaving the outfall. The equations above exhibit the conditions for maximum loadings. Table2, below depicts how the control of concentrations can allow for an increase of flow without an increase in loading. For example with CBOD the concentration is half the allowable limit, therefore the flow can theoretically be doubled as long as the current water quality can be maintained. Table2 2015 Effluent Maximum Values
CBOD TSS
709 lbs
=
16.7
MGD
*
5.1
mg/L
*
8.345
39.2
MGD
*
6.5
mg/L
*
8.345
2,127
lbs
=
Total Phosphorus
108
lbs
=
3.4
MGD
*
3.8
mg/L
*
8.345
Total Nitrogen
231
lbs
=
3.7
MGD
*
7.4
mg/L
*
8.345
As can be seen in the Table2, CBOD and TSS are currently removed to a very low level. This has been accomplished because the City invested $5 million in 1996 and an additional $1.3 million in 20 I 0 to construct and rehabilitate the tertiary treatment process. In 2017 the Wastewater Management Division will complete a comprehensive nutrient study of the facility and the segment of the Santa Fe River affected by the outfall. It is expected that this study will detennine reasonable treatment goals for each process in regards to nutrient removal. In addition the study will detennine realistic expectations for the next NPDES pe1mit renewal. The study will also look at the oxygen uptake rate in the aeration process which will provide valuable intonnation as the Division begins the major rehabilitation of the aeration system starting in fiscal year 17/18 (as identified in the 5-year CIP). In order to comply with the cuiTent NPDES pennit assuming a 5.6 MGD flow, within the next three years the facility will need to consistently remove Total Phosphorus to below 2.3 mg/L and Total Nitrogen below 4.9 mg/L as monthly averages. In order tor the facility to treat the design flow of 13 MGD at the current pennit loading limits, Total Phosphorus would need to consistently be removed to Jess than I mg/L and Total Nitrogen would need to be removed to less than 2.2 mg/L as monthly averages.
4
In Summary, the new limits for Total Nitrogen and Total Phosphorus have been exceeded on at least one occasion in 2015 and in 2016. Staff believes that the new NPDES permit limits can be met by increasing nutrient monitoring, which will provide a more accurate representation of nutrient levels in the effluent, and by optimizing the current treatment processes to treat the current flow into the treatment facility. As more effluent is treated, the likeliness of more exceedance will also increase. Ultimately a treatment train for nutrient removal wiJI need to be added to the facility to treat future flows and future, more stringent, permit requirements.
ATTACHMENTS:
o 2016 Wastewater Treatment Facility Masterplan Treatment Process Capacity Numbers o 2015/2016 SummaryofWaterQuality Plant Data
5
2016 Wastewater Treatment Facility Masterplan Capacity Numbers 35
c
~
~
30
27
s:::::
>
·-....,u
25
• Loading Based Capacity
n:l
c..
n:l
u
II) II)
20
17.8
(U
u 0 s...
D Hydraulically Based Capacity
15
0.
...., s:::::
(U
E ...., m (U
10
~
5
Wastewater Treatment Facility Processes
6
CITY OF SANTA FE WASTEWATER TREATMENT FACILITY 2015 Plant Data 2015 Annual Summary
INFLUENT EFFLUENT FLOW FLOW MOD MOD
1,976 5.42 6.75
Sum Daily Avg Daily Max
t=~r 28 57
EFFLUENT BIOLOGIAL OXYGEN DEMAND MOIL 23,4540bs) 1.80 5.08
EFFLUENT TOTAL SUSPENDED SOLIDS MG/L 20,848 (lbs) 1.60 6.50
TOTAL NITROGEN LBS/DAY 30/DAY AVERAGE 60,137 164.76 289.50
TOTAL PHOSPHORUS LBS/DAY 30/DAY AVERAGE 14,381 39.4 102
TREATED EFFLUENT REUSE MILLION GALLONS 342 0.94 3.22
Through August 2016 Plant Data 2016 Accumulative Summary
Sum Daily Avg Daily Max
INFLUENT EFFLUENT FLOW FLOW MGD MOD
i
1,258 5.18 6.21
922 3.78 6.61
EFFLUENT BIOLOGIAL OXYGEN DEMAND MG/L 16,619 2.16 4.78
EFFLUENT TOTAL SUSPENDED SOLIDS MG/L 19,543 2.54 6.0
TOTAL NITROGEN LBS/DAY 30/DAY AVERAGE 36,207 149 306.7
TOTAL PHOSPHORUS LBS/DAY 30/DAY AVERAGE 12,709 52.3 302
TREATED EFFLUENT REUSE MILLION GALLONS 402 1.65 4.91
7
