Document gDrOOewYr5JDNkxKQ08Ynz2B9
Region 6 - Enforcement & Compliance Assurance Division
INSPECTION REPORT
Inspection Date(s): Media Program: Regulatory Program(s)
Company Name: Facility Name: Facility Physical Location:
(city, state, zip code) Mailing address:
(city, state, zip code) County/Parish: Facility Phone Number Facility Contact:
12/6/2023 Water NPDES
NEW MEXICO WATER SERVICE
Rio Del Oro Wastewater Treatment Plant
1 PNM Access Road
Los Lunas, New Mexico
401 Horner
Belen, New Mexico 87002
Valencia
505-864-2218/505-463-1395
Bobby Towle
WWTP Supervisor
BTowle@NewMexicoWater.com
FRS Number: Identification/Permit Number: Media Identifier Number: NAICS: SIC:
110009831110 NM0030414 NA 221320 4952
Personnel participating in inspection:
Gene Garcia
New Mexico Water Service
David Esparza
USEPA/R6-ECDWM}
WWTP Operator-4 Environmental Engineer
EPA Lead Inspector Signature/Date
DAVID ESPARZA
David Esparza
Digitally signed by DAVID ESPARZA Date: 2024.01.02 09:12:38 -07'00'
Date
Supervisor Signature/Date
ROBERTO BERNIER Date: 2024.01.02 13:35:19 -06'00' Digitally signed by ROBERTO BERNIER
Roberto Bernier
Date
6ENFORM-019-R8.2 (02/12/2020)
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Section I - INTRODUCTION
New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
PURPOSE OF THE INSPECTION
EPA Region 6 inspector David Esparza arrived at the Rio Del Oro, Wastewater Treatment Plant (WWTP) at approximately 2:00 PM on December 6, 2023, for an unannounced Compliance Evaluation Inspection (CEI). I met with Mr. Gene Garcia, a Level 4 operator with New Mexico Water Service (NMWS). Note: NMWS is the owner and operator of Rio Del Oro WWTP. I presented my credentials to Mr. Garcia and informed him this was an EPA inspection to determine the WWTP's compliance under the Clean Water Act (CWA). This CEI was conducted under the authority of the National Pollutant Discharge Elimination System (NPDES) permit program, in accordance with the CWA. The generation of this report is based on information supplied by New Mexico Water Service representatives, observations made by the EPA inspector, and records and reports maintained by the permittee (NMWS) and EPA. Before leaving the facility on December 6, 2023, an exit briefing was held with Mr. Garcia to explain areas of concern noted at the time of the inspection.
FACILITY DESCRIPTION
The WWTP is a minor discharger with a design flow of 0.3 million gallons per day (MGD), with an average daily flow of approximately 0.175 MGD. The private treatment facility is located at 1 PNM Access Road, Los Lunas, Valencia County, New Mexico (depicted in Aerial Image #1 below). The facility location can be further described as approximately 600-feet East of the Tom Cemetery or approximately 1,800-feet Southeast of the University of New Mexico-Valencia Campus. The WWTP facility serves a population of approximately 3,300 persons. The facility is operated from 7:30 AM to 4:30 PM Monday through Friday with a total of one (1) full-time staff.
In approximately 2005 New Mexico Water Services Company commenced an upgrade of the 0.1 MGD, single-train conventional activated sludge (CAS) with a membrane bioreactor (MBR) system to meet Class 1A effluent for reuse. The MBR was commissioned circa July 2006.
Raw sewage is discharged into one (1) of two (2) automatic fine bar screens (one on-line; one standby) that are provided with a common conveyor/washer/compactor (CWC). The CWC removes organics from the screens and automatically discharges the washed and compacted screenings into a dumpster that is transported and disposed of at a landfill.
The effluent from the bar screen discharges into the pre-air basin to be mixed with the activated sludge (mixed liquor suspended solids). This process allows removal of the biological oxygen demand (BOD) and total suspended solids (TSS) in the pre-aeration basin, in addition to nitrogen, which is removed through alternating periods of aeration (nitrification) and anoxic mixing (denitrification).
Two (2) submersible pumps pump the mixed liquor from the pre-aeration basin into the two (2) separate bioreactors. Each reactor is equipped with four (4) submerged membrane units (SMU) comprised of 200 flat plate filters in each unit. Facility effluent is withdrawn through the flat plate membranes (filtered) by permeate pumps (two on-line; one standby), thence traverses through two (2) alternating ultraviolet (UV) disinfection units (one on-line; one standby), thence to a holding basin
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New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
for irrigation reuse upon request by the Valley Improvement Association (VIA) for watering of their parks. This facility has a discharge permit from NMED (NMDP- 1569) for re-use water, Class IA.
The MBR is monitored and controlled by a programmable logic controller (PLC) that also provides supervisory control and data (SCADA) acquisition for alarm notification. Operator control is provided through a human-machine interface that is simply a PC located in the administration/laboratory building. In the event of a failure of the PLC, the facility can also be operated manually.
Aerial Image #1: Overall view of the Rio Del Oro Wastewater Treatment Plant. Aerial from Google Earth maps
Table 1: Rio Del Oro Lift Stations
Lift Station Number
Tom Vista 1 Tom Vista 2 RDO/UNM
La Canada Monzarro Eastland
Location by Street Address
2 Avenida Serena Place 73 Tome Vista Drive 266 La Entrada Road 70 Camino La Canada 30 Mission Court 7 Hermanos Loop
All the lift stations have emergency back-up power in the event of a power outage. The WWTP onsite generator and all lift stations back-up power is exercised every Wednesday under a load.
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New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Rio Del Oro does not have any identified Industrial Users (IU), though one (1) commercial and five (5) education entities contribute to their WWTP.
Additionally, the WWTP maintains an 500K-gallon evaporative lagoon in the event of an emergency. This onsite lagoon measures approximately 0.52 acres in surface area.
Additionally, the WWTP has implemented written policies and procedures to address any potential sanitary sewer overflow events (SSOs), and standard operating procedures (SOPs) pertaining to facility operations and maintenance (O&M).
Section II - OBSERVATIONS
I observed the following and/or information was provided, stated, or requested of the WWTP staff.
The observed affixed thermometer within the sample storage refrigerator did not exhibit any visible evidence of proper and timely calibration of temperature recording devices (thermometers). In response to the Request for Information (RFI) dated December 7, 2023 (Appendix 3 Request for Information (RFI)). The WWTP simply responded "none". Therefore, the integrity or stability of the collected samples cannot be guaranteed; thus, the results could be inaccurate or in error.
The observed laboratory glass sample containers appeared to lack proper cleaning.
It was stated the WWTP had experienced three (3) Sanitary Sewer Overflow (SSO) events in conjunction with their NPDES permit as follows: at the WWTP (June 17, 2021), Tom Vista (August 10, 2021) and the Eastland Hills lift station (September 7, 2021), respectively (Appendix 4 Transmittal Notification of SSO Event).
It was stated that the WWTP typically discharges the disinfected effluent through a closed conduit pipe to the Las Maravillas Homeowners Association lagoon located approximately 1-mile east of the facility.
The WWTP had secure perimeter fencing; thus, limiting access. The overall WWTP's operations and maintenance (O&M), and general facility housekeeping appeared to be in good order.
Section III - AREAS OF CONCERN
A review of the submitted Integrated Compliance Information System (ICIS) Discharge Monitoring Reports (DMR) data for the period January 101, 2019, through September 30, 2023, indicates numerous NPDES permit excursions with respect to Escherichia coli (E. coli) and Percent (%) Suspended Solids removal (Appendix 2 ICIS E90 Effluent Violations).
The WWTP had experienced three (3) Sanitary Sewer Overflow (SSO) events in conjunction with their NPDES permit as follows: at the WWTP (June 17, 2021), Tom Vista (August 10, 2021) and the Eastland Hills lift station (September 7, 2021), respectively (Appendix 4 Transmittal Notification of SSO Events).
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New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
The observed affixed thermometer within the sample storage refrigerator did not exhibit any visible evidence of proper and timely calibration of temperature recording devices (thermometers). In response to the Request for Information (RFI) dated December 7, 2023 (Appendix 3 Request for Information (RFI)). The WWTP simply responded "none". Therefore, the integrity or stability of the collected samples cannot be guaranteed; thus, the results could be inaccurate or in error.
The WWTP description of Outfall 001 states the discharge is to an arroyo named La Caada de la Loma de Arena thence to La Constancia Ditch, and finally to Rio Grande (Aerial Image #2). However, if the statement of the closed conduit discharge to the Las Maravillas Homeowner's Association lagoon is correct (Aerial Image #3) this is contrary to the permitted outfall location.
Aerial Image #2 View of the Rio Del Oro WWTP and the permitted flow path from Outfall 001 into the La Caada de la Loma de Arena arroyo
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New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Aerial Image #3 View of the Rio Del Oro WWTP (yellow pin) and the stated discharge to the Las Maravillas Subdivison (green pin) located approximately 1-mile east of the WWTP. Section IV - RECOMMENDATIONS
Ensure all appurtenant temperature recording devices (thermometers) within the on-site laboratory, flow meters, automatic samplers, etc. are calibrated in accordance with recognized protocol.
Ensure all appurtenant laboratory testing equipment (flasks, beakers, etc.) maintain proper cleaning and storage.
EPA Region 6 inspector David Esparza conducted a closing conference at Rio Del Oro Wastewater Treatment Plant at approximately 3:00 PM on December 6, 2023, for the inspection. During the closing conference, David Esparza reviewed the Areas of Concern noted during the inspection. Section IV - FOLLOW UP The following information was received by EPA on December 14, 2023, after exiting the Facility on December 6, 2023.
See Appendix 3 Request for Information (RFI) and the Rio Del Oro/New Mexico Water Services Response
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Section V - LIST OF APPENDICES
New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Appendix 1 - Photo Log - 7 photos taken 12/06/2023 Appendix 2 - ICIS E90 Effluent Violations Appendix 3 - Request for Information (RFI) Appendix 4 - Transmittal Notification of SSO Events Appendix 5 - Rio Del Oro Site Map and Outfall Points of Reference
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New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Appendix 1 Photograph Log
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 1
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View of WWTP's pre-air basin. Bar screen and entrance headworks on right side of photograph. (DSCN2678). Photographed by D. Esparza
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 2
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View of the bioreactors. (DSCN2681). Photographed by D. Esparza
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 3
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View of the ultraviolet (UV)disinfection treatment system. (DSCN2682). Photographed by D. Esparza
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 4
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View of the one (1) of the ultraviolet (UV) disinfection treatment systems (UV-2) injection ports exhibiting corrosion. (DSCN2683). Photographed by D. Esparza
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 5
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View of the sodiun hypochlorite (UN1791) un-restrained drum. (DSCN2684). Note: not clear why the sodium hypochlorite (typically used in wastewater treatment as an oxidizing and disinfection agent) and the UV are plumbed into the system. Photographed by D. Esparza
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 6
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View of the onsite back-up generator. (DSCN2685). Photographed by D. Esparza
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Photograph Log
Photo No. 7
Location: Rio Del Oro Wastewater Treatment Plant
City: Los Lunas
County/Parish: Valencia
State: New Mexico
View looking south of the 500K-gallon emergency storage lagoon. (DSCN2675). Photographed by D. Esparza
New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Appendix 2 Review of the ICIS
E90 Effluent Violations
E90 Effluent Violations From 01/01/2019 - Present
NM0030414
RIO DEL ORO WWTF-NM W
Monitoring Period End Date 09/30/2022 10/31/2022 10/31/2022 01/31/2023 01/31/2023 06/30/2023 07/31/2023 07/31/2023 07/31/2023 07/31/2023 08/31/2023 08/31/2023 08/31/2023 08/31/2023 09/30/2023 09/30/2023 09/30/2023
Perm Feature ID 001 001 001 001 001 001 001 001 001 001 001 001 001 001 001 001 001
Limit Set Designator A A A A A A A A A A A A A A A A A
Parameter Desc
Statistical Base Short Desc
E. coli
30DAVGEO
E. coli
30DAVGEO
E. coli
DAILY MX
E. coli
30DAVGEO
E. coli
DAILY MX
E. coli
30DAVGEO
E. coli
30DAVGEO
E. coli
30DAVGEO
E. coli
7DAV GEO
E. coli
DAILY MX
E. coli
30DAVGEO
E. coli
30DAVGEO
E. coli
7DAV GEO
E. coli
DAILY MX
E. coli
30DAVGEO
E. coli
DAILY MX
Solids, suspended percent MO AV MN
Limit Unit Short Desc
Limit Value
BCFU/d 1.43
BCFU/d 1.43
CFU/100126
BCFU/d 1.43
CFU/100126
BCFU/d 1.43
BCFU/d 1.43
CFU/100126
CFU/100126
CFU/100126
BCFU/d 1.43
CFU/100126
CFU/100126
CFU/100126
BCFU/d 1.43
CFU/100126
%
85
DMR Value Qualif ier Code = = = = = = = = = = = = = = = = =
DMR Value 1.89 4.2 137.6 2.49 130.3 1.54 16.2 186.9 186.9 816.4 70.47 1773.1 1773.1 2419 2.87 131.4 82
New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Appendix 3 Request for Information (RFI)
and The New Mexico Water Service Response
Esparza, David
From: Sent: To: Cc: Subject: Attachments:
Towle, Bobby <BTowle@NewMexicoWater.com> Thursday, December 14, 2023 4:15 PM Esparza, David Vaughn, Alan; Matthews, Rachel RE: Rio Del Oro Wastewater Treatment Facility (WTF) (NM0030414) Flow meter calibrations.pdf; Flow records.pdf; Liftstations address, pump sizes.pdf; Facility site, equiptment,basins,outfall.pdf; SOP.pdf; SSO-Event letters.pdf
Caution: This email originated from outside EPA, please exercise additional caution when deciding whether to open attachments or click on provided links.
Good afternoon Mr. Esparza
Attached is the information you requested. If you need anything else, don't hesitate to contact me. I will be sending another email with the 2 years' worth of analytical results due to not enough space.
Sincerely,
Bobby Towle
Wastewater Supervisor
NEW MEXICO WATER SERVICE
OFFICE #: 505-864-2218 Mobile #: 505-463-1395 Fax #: 505-864-8438
Quality. Service. Value.
calwater.com
From: Esparza, David <esparza.david@epa.gov> Sent: Thursday, December 7, 2023 2:51 PM To: Towle, Bobby <BTowle@NewMexicoWater.com> Cc: Vaughn, Alan <Vaughn.Alan@epa.gov>; Matthews, Rachel <Matthews.Rachel@epa.gov>; Esparza, David <esparza.david@epa.gov> Subject: Rio Del Oro Wastewater Treatment Facility (WTF) (NM0030414)
Mr. Towle:
As I discussed, this is my follow-up to our telephone conversation this afternoon December 7, 2023. To reiterate my understanding, I was informed you would provide copies or make available the information as requested. Additional information might be requested after my review of the received information. The
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specific request for information (RFI) will be delineated below. Therefore, please forward by email the requested information as soon as possible, but no later than close of business December 14, 2023.
A complete electronic copy of your Sanitary Sewer Overflow (SSO) protocol, inclusive of all SSO events for the previous two (2) years. See Attachment (SSO- Event letters)
A complete electronic copy of your Standard Operating Procedures (SOPs) (i.e., WTF treatment process and on-site laboratory) and clarification how often it is updated. See Attachment for SOP. On-site lab is for in-house process control, MLSS,R.A.S and % T.S updated on as needed basics. (SOP)
A current copy of the facility Site Map delineating the total area footprint, locations/volumes of any onsite fuel storage tanks, delineation of processes (i.e., headworks, EQ basins, chlorination, etc.), all associated ancillary equipment and outfall(s). See Attachment (Facility site, equipment, basins, outfall)
Identification of the quantity, location, and names of any lift stations (LS), wet wells etc. See Attachment (Lift stations address, pump sizes)
Clarification if the identified LSs have on-site back-up power or quick connects in the event of power outages. See Attachment (Lift stations address, pump sizes)
Electronic copies of calibration and maintenance records of your flow measuring (meter) devices, inclusive of serial numbers (S/N) for the previous three (3) years. Found 2 years see attachment. (Flow meter calibrations)
Electronic copies of your flow measurement records for the previous 1-year period. See Attachment (Flow records)
Clarification the generator observed on-site is capable of fully operating the entire WTF and how often it is exercised. The on-site EMG was oversized for the facility. The on-site E.M.G runs every Wednesday for approximately 30 Min under load.
Electronic copies of calibration and maintenance records of your temperature recording devices (thermometers) within the on-site laboratory. None
Electronic copies of your analytical analysis reports for the previous two (2) years, both internal and external. See Attachment (this will be attached to another email following this one)
Clarification of the WWTP's current staffing and hours of operation. 1 Operator on-site is Mr. Baca operator # NM10140 working hours are 7:30am - 4:30pm
Clarification of the type of electronic monitoring utilized in operating the WWTP (i.e., SCADA, PLC, etc.). Clarification how the operator is alerted to a WWTP situation/event. Vendor supply HMI (human machine interface) Allen Bradly control logics. Vendor supply Wonderware SCADA. Alarms transmitted to the on-call phone. We only receive a message loss of aeration that can be intrusion, power failure etc..
Identification of the industrial/commercial/educational entities contributing to the WTF. No Industrial. 1 commercial, and 5 schools.
Electronic copies of applicable service agreements with respect to the industrial/commercial/educational entities and the Las Maravillas Homeowners Association. None to my knowledge that I'm aware of.
Please let me know if you have any questions.
David A. Esparza, P.E. Environmental Engineer U.S. Environmental Protection Agency Water Enforcement Branch-Municipal/Industrial Section Mail Code: 6-ECDWM 1201 Elm Street, Suite 500 Dallas, Texas 75270 (505) 366-8402 eMail: esparza.david@epa.gov
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This e-mail and any of its attachments may contain New Mexico Water Service Company proprietary information and is confidential. This e-mail is intended solely for the use of the individual or entity to which it is addressed. If you are not the intended recipient of this e-mail, please notify the sender immediately by replying to this e-mail and then deleting it from your system.
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New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Appendix 4 Transmittal Notification
of SSO Events
New Mexico Water Service/ Rio Del Oro WWTP Inspection Date 12/06/2023 Permit Number NM0030414
Appendix 5
Rio Del Oro Site Map and
Outfall Points of
Reference
Rio Del Oro/Las Maravillas
Permitted Outfall La Canada de La Loma de Arena Arroyo- and stated Outfall Discharge
N
4000 ft