Programs

DEQ approves proposed final grading plan modification

The owner of Riverbend Landfill, Waste Management, proposed to modify the slopes of a 20-acre portion of the landfill. The proposal involves construction of a 5-foot tall berm uphill from the existing perimeter berm. An impermeable cover will be placed over the 20-acre area and waste will be placed over this new overliner (which serves as a liner beneath new waste and a cover over existing waste).
The additional waste will be placed at a maximum slope of 3 to 1 (horizontal to vertical). Because of waste settlement, this slope will eventually flatten to less than 3.5 to 1. The modification allows capacity for an additional 490,000 cubic yards of waste.
DEQ reviewed this application with the help of a seismic consultant, and has concluded that it meets state and federal regulatory requirements, including those for seismic stability.

A public comment period was held from April 3, 2017 through May 8, 2017. A public hearing and information meeting were held on May 2, 2017. DEQ received numerous comments regarding this proposal.
 

 

​Nuisance Odor Investigation

After receiving a sufficient number of complaints, DEQ has started a nuisance odor investigation at Riverbend Landfill. The investigation is a step in DEQ’s Nuisance Odor Strategy. As part of the investigation, DEQ will be conducting odor surveys periodically throughout the year.
 
Groundwater sampling results taken in May 2016 at one of the monitoring wells at Riverbend Landfill showed an exceedance of four water quality parameters. Monitoring well number 12A exceeded limits for bicarbonate alkalinity, dissolved magnesium, dissolved sodium, and total dissolved solids. These are nontoxic substances that occur in nature. However, the concentrations found in this well may indicate a change in groundwater quality related to the landfill.
 

The landfill’s permit required the well to be resampled, which occurred in June 2016. These results confirmed exceedances for three of the four parameters: bicarbonate alkalinity, dissolved magnesium and dissolved sodium.

 

In response to these results, Waste Management prepared a work plan to assess the source of the change in groundwater quality. That work plan is provided here: 

 
Waste Management has submitted an application for a 29-acre expansion of the landfill. DEQ is reviewing the application documents, which include:
 
 

The U.S. Army Corp of Engineers issued a public notice related to a proposed dredge and fill permit at the Riverbend Landfill. The public notice incorporates the public notice for DEQ’s 401 Certification for the project.

 

DEQ delays action on expansion request pending valid Land Use Compatibility Statement

 

DEQ is not currently acting on a permit modification request that would allow an expansion of Riverbend Landfill. The request is on hold until DEQ receives a valid Land Use Compatibility Statement, or LUCS.

The landfill’s owner, Waste Management, had submitted the compatibility statement with the modification request. However, the land use decisions supporting that compatibility statement were legally challenged, and the Land Use Board of Appeals recently remanded a portion of the decision that underlies the LUCS back to Yamhill County for further consideration.

DEQ will wait until Yamhill County issues a new decision or DEQ otherwise receives a valid LUCS supporting the modification to the permit before moving forward with permitting decisions on the expansion.

 
​DEQ is responsible for managing three permits for the facility:
Stormwater 1200-Z Discharge Permit No. 13016, File No. 106959

These permits contain the limits, standards, monitoring, testing, recordkeeping, and reporting requirements based upon Oregon statutes, DEQ rules, or federal rules.

​The facility's permits require the company to monitor environmental conditions at the site in accordance with the facility's Environmental Monitoring Plan.

The facility records the results of this monitoring in an annual environmental monitoring report. The most recent of these reports is found at this link:

​There was a discrepancy regarding the location of the landfill relative to floodplain and flood way boundary, as shown on flood insurance maps issued by the Federal Emergency Management Agency, or FEMA. On May 31, 2012, Waste Management submitted a request to FEMA for a Letter of May Revision to address this discrepancy. Portions of this submittal are found here:

On December 26, 2012, FEMA issued the requested Letter of Map Revision, which indicates that the landfill is outside the floodplain and flood way boundaries. A copy of the Letter of Map Revision can be found here:

There is localized groundwater contamination, as indicated by the presence of volatile organic compounds in one groundwater monitoring well. Volatile organic compounds are of particular importance in evaluating a landfill's effects on groundwater for a couple of reasons.  They move fairly quickly through groundwater and therefore provide an early indication of a problem. Unlike other contaminants, such as metals, most volatile organic compounds do not occur in nature, so if they are detected, they are likely from the landfill. We suspect the contaminants found in this well may have been carried by landfill gas moving under the ground. Concentrations have dropped over the years, primarily because the owner has installed an extensive landfill gas removal system.

Low concentrations of volatile organic compounds have also been detected in other wells but subsequent sampling has not found the compounds in these wells. The permit requires that if a volatile organic compound is detected and is not due to sample handling or lab contamination, the well must be resampled to confirm the presence of that contaminant. Confirmation sampling has never shown the presence of volatile organic compounds in any of the wells, other than the one mentioned above.

More information regarding this is found in the attached report:
Stormwater Pollution Control Plans

As part of the NPDES 1200-Z General Stormwater Permit requirements, facilities are required to submit a stormwater pollution control plan. The SWPCP must be kept current and updated to reflect site changes. SWPCP revisions must be submitted to the DEQ only if they are made for the following reasons: changes are made in site contact(s); in response to a corrective action or inspection; changes to the site or control measures that may significantly change the nature of pollutants present in stormwater discharge; or significantly increase the pollutant(s) levels, discharge frequency, discharge volume or flow rate, or changes to the monitoring locations or outfalls.

The following links include the SWPCP and related revisions received by DEQ:

Discharge Monitoring Reports
Facilities are required to sample stormwater four times per year under the 1200-Z general permit (unless a monitoring waiver has been approved or if monitoring variance criteria due to no discharge have been met). Riverbend is required to analyze these samples for copper, lead, zinc, pH, total suspended solids, oil and grease, and e.coli. The results from these sampling events are reported on the discharge monitoring report and submitted to DEQ by July 31 of each year.

Inspections
The NPDES 1200-Z General Stormwater Permit compliance can also be evaluated through an on site compliance inspection. The most recent stormwater inspection conducted by DEQ Stormwater program staff is below:

Tier I Corrective Action
If stormwater sampling results exceed any of the statewide benchmarks , sector specific benchmarks , or reference concentrations for impairment pollutants , the permit registrant must within 30 calendar days of obtaining the monitoring results perform a Tier I Corrective Action Response. Tier I reports must be retained on site and submitted to DEQ or Agent only upon request.

The previously issued 1200-Z General Stormwater permit (expired in 2012) required facility to submit an Action Plan to DEQ for benchmark exceedences. Copies of the Action Plans are available through DEQ Public Records Request webpage.

Future stormwater plans and discharge monitoring reports will be posted as they are received.

Inspections

EPA and the Title V operating permit program require that inspections of the facility occur at least every other year. Prior inspections of the facility have shown it to be in compliance with the Title V permit conditions. The inspection reports for 2010 and 2012 are found below:

Annual Report
The Title V operating permit requires semiannual reports by the facility certifying compliance or noncompliance with the various conditions in the permit. Annual reports containing this semiannual compliance certification as well as other operating data and annual emissions estimates are also required.

Monthly Reports
As a result of citizen input and concerns during the last Title V permit renewal, the most recent Title V permit requires the facility to submit monthly reports concerning operational information, odor complaints, and odor surveys conducted around the landfill. 

Leachate releases

On February 10, 2014, landfill personnel observed leachate escaping from the landfill’s northern boundary. Waste Management reported that this leachate reached a creek approximately 300 feet from the landfill. This leachate was primarily liquid that had collected in the landfill’s gas extraction wells. To keep the extraction wells working properly, this leachate is routinely pumped from the wells to three 22,000-gallon storage tanks near the north side of the landfill. This leachate is kept separate from the majority of the landfill’s leachate, which is pumped to the onsite leachate pond. This reason for this separation is that leachate associated with the gas extraction wells is more concentrated than the rest of the landfill leachate, and is therefore sent to a different offsite facility for treatment and disposal. Tanker trucks that routinely haul this leachate to an offsite treatment plant were unable to get to the site because of heavy snow and icy roads. Flow of leachate from the landfill to the tanks was stopped because the tanks were full. This is believed to be the reason leachate began seeping from the landfill. To prevent this problem in the future, Waste Management has connected these tanks to the pipeline leading to the onsite leachate storage pond.

Impacts to the creek were evaluated in a March 13, 2014 report prepared by Waste Management’s consultant, CH2M HILL. The CH2M HILL’s  report concludes that “No mortality of aquatic flora or fauna was observed during either site visit [conducted on February 12 and 21, 2014]. Overall, the impact to aquatic biota was estimated to be minimal on the basis of the high flows of the unnamed creek and the South Yamhill River, and the comparison to aquatic water quality criteria and human health criteria.” 

DEQ inspected the site on February 12, 2014. View the inspection report, along with photographs. DEQ concurs with the findings of the consultant's report. However, in light of the release of leachate to the creek, DEQ is pursuing enforcement action against the landfill.

Another consultant for Waste Management, SCS Engineers, sampled soil in the area between the landfill and the creek through which the leachate traveled. View the results of the SCS study.

A previous seep was found on January 28, 2014, approximately 400 feet west of the February 10 seep. This leachate migrated beyond the perimeter of the landfill, but did not travel far from the landfill perimeter. This release was from an old perimeter French drain that was clogged as the result of recent construction of a stormwater diversion swale. The drain had been installed during construction of the landfill cell to convey leachate to the leachate collection line that runs to the onsite leachate storage pond. To address this problem, the landfill contractor removed all drain rock from the French drain along that portion beneath the stormwater diversion berm. Between January 28 and 29, this rock was removed and the area was backfilled with compacted clay. Four vertical 12-inch sump pipes were installed and backfilled with drain rock. Soil from the impacted area north of the landfill was sampled on January 29. Soil impacted by the leachate release was then excavated, and a vacuum truck was used to remove standing stormwater that may have been contaminated by the release. Soil from this area was resampled on January 31. Results were provided in a technical memorandum dated March 14, 2014, prepared by SCS Engineers. These results indicate that residual contaminant concentrations are below safe levels.

Boring Logs
Numerous studies of hydrogeologic conditions have been conducted by Waste Management's consultants.  These are based on boring logs that are recorded each time a well or piezometer is drilled. Monitoring wells are used to draw water samples for lab analysis, and to measure the elevation of the groundwater surface. 

Elevations of groundwater relative to bottom of waste
Waste Management's consultant prepared a report in November 2012 that assesses groundwater elevations relative to the elevation of the bottom of waste at the landfill. As shown in this report, the elevation of groundwater is higher than the bottom of waste in portions of the landfill. It is important to note that the waste lies above a liner that prevents the escape of contaminants. The liner system has become increasingly substantial as new sections of the landfill have been built, to provide a more effective barrier between waste and groundwater.

The report does not evaluate the three oldest cells (Modules 1 through 3), whose liner systems consist of low-permeable soil but do not include plastic geomembranes. This is because the consultant was unable to find base grade information for these older landfill cells.

Potential for migration of the South Yamhill River
Residents have expressed concern about the potential for the South Yamhill River to migrate over time, because it could therefore move closer to the landfill. This issue was evaluated in a September 2012 report by Waterways Consulting, Inc. The report concludes that the river has not migrated in this direction substantially in the past. Among the factors considered, the report points to the presence of 3,000-year-old Native American artifacts found in the land between the river and the landfill. 

Closure and post-closure financing
Landfills are required to set aside funds sufficient for proper closure of the landfill and 30 years of post-closure maintenance and monitoring. Estimates of the necessary funding must be revised every year.  

Financial assurance documents:

Topographic Maps

Landfill contours are documented using aerial photography every year. The most recent topographic map, created in April 2015, is found here:

Recent Cell Construction
The most recent landfill cell was 8D, built in 2009. Construction drawings are found here:

 

Contact

 
Bob Schwarz, 541-298-7255 ext. 230, toll free at 800-452-4011