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Home > Conimicut Odors


 

Update on Odors in Conimicut
Overview

On Friday, September 5, inspectors from the Department of Environmental Management responded to complaints from residents in the Conimicut section of Warwick about sewage-like odors in the vicinity of Shawomet and Bellman Avenues. A DEM inspector confirmed that objectionable odors were detected on Shawomet Avenue, coming off the water and carried by a northerly wind. The source of the odors could not be determined, and DEM has continued to look at several possible natural and man-made causes. The Department investigated the possibility of releases from local wastewater treatment plants, exposed manholes associated with local sewer extension work, localized bay problems, and other possible local sources. In addition, state and federal agencies were also contacted about the matter.

DEM sent inspectors to the area again on Tuesday, September 9, at which time discolored bay water, with an associated stench of rotting seaweed, was observed. The Department continued to investigate possible local sources for the odors. Residents complained that the odors were similar to raw sewage, leading many to suspect that it may be due to a sewage overflow that was traveling down the Bay from Providence. DEM does not believe this is the cause of the odors, because none of the sewage treatment plants reported overflows and the Department has not found any evidence of any recent sewage treatment plant failures. Earlier that day, DEM staff assessed the area aboard a boat traveling just offshore, and detected no odors. The vessel was unable to get close to shore because of the area's shallow waters. However, DEM staff did detect the odors onshore shortly thereafter, indicating that the source of the odors seems to be located in the shallow section of the cove. The configuration and shallowness of Conimicut Cove, combined with the northerly winds that have been occurring over the past couple of weeks, are thought to be the key factors causing the odors to be particularly severe in this area.

On Wednesday, September 10, inspectors from the Department returned to the area to collect air samples. The odors were not as severe as they had been on the previous day, although a slight hydrogen sulfide odor was detected. Also observed just offshore were piles of dead soft-shelled clams and huge mats of decaying seaweed. DEM staff also met with local residents and observed conditions of a "black-brown" substance on their homes. The Department suspects the substance may be mold and mildew, perhaps exacerbated by the conditions in the cove, but continues to investigate and further asses this situation.

Also on Wednesday, DEM took water samples to assess bacteria concentration and to determine if decaying seaweed and bacteria are present in the water in Conimicut Cove. Test results are due next week, but a preliminary examination of the water samples indicates that they are largely comprised of decaying seaweed. This result, combined with all other observations to date, strongly suggests that the odors have been caused by decaying seaweed and clams in the area. Decaying matter often releases hydrogen sulfide, a noxious gas that is a known cause of offensive odors. It has been suggested that elevated hydrogen sulfide levels in the air could be the cause of reported tarnishing silver and other discolorations that have been reported in the Conimicut area. (Click here for more information on hydrogen sulfide)

Today, Thursday, September 11, DEM received the results from yesterday's air sample. The results indicated that only a trace amount of hydrogen sulfide was present in the air at the time the sample was taken. Residents are reporting that conditions today are continuing to improve.

DEM will continue to monitor and investigate the situation. As further information develops regarding the source of the odors, DEM will provide updates at this location on the Department's website. If the odors persist or worsen, residents should notify DEM by calling the Department's Office of Compliance and Inspection at 222-1360.

  • DEM is aware that the odors are persisting.


  • DEM continues to believe that the odors are being caused by decaying organic matter (dead clams, seaweed, etc.), which is essentially trapped in the cove on the north side of Conimicut Point and giving off hydrogen sulfide gas.


  • Results of water sampling, conducted on September 10, reveal relatively low levels of fecal coliform bacteria (39 MPN and 49 MPN), indicating that the problem is not sewage related.


  • DEM plans to conduct additional air monitoring on the morning of 9/16 to assess hydrogen sulfide concentrations in the air


  • DEM is also investigating the possibility of having a lab analyze the substance causing discoloration on certain houses in the neighborhood.


  • DEM and HEALTH, working with the City of Warwick, are planning to distribute a Health and Environmental Advisory to residents in the neighborhood, summarizing what is happening, what the state is doing, and what local residents can do.


  • DEM will continue to post updates at this location on its website.


  • DEM urges residents to notify DEM's Office of Compliance and Inspection (222-1360) if the odors become worse or if any suspected sources other than the rotting clams and seaweed are identified.
  • As indicated in yesterday's update, DEM did conduct air monitoring for 2 ½ hours this morning on the shore in Conimicut. We did find levels of hydrogen sulfide in the air with a high reading of 22 parts per billion (PPB) for a 10-minute period.


  • Today's reading confirms that gas is being emitted from the cove but below the level at which federal guidelines recommend avoiding long term exposure. All indications are that the odors in the neighborhood are not as intense as they have previously been. This morning's light southeast wind contributed to the relatively good conditions in the Conimicut neighborhood.


  • DEM will be positioning an air monitoring device in the neighborhood and will continue to collect data from the air monitor on a periodic basis. The Department will post monitoring results at this location on its website when they become available.


  • According to the Department of Health, short term exposures to this odor may make some people feel sick, but we only anticipate passing discomfort. If you have a chronic health condition, and feel sick, contact your health care provider. Go to www.HEALTH.ri.gov for advice on how to avoid the odors - especially at low tide.


  • DEM urges residents to notify DEM's Office of Compliance and Inspection (222-1360) if the odors become worse or if any suspected sources other than the rotting clams and seaweed are identified.
  • DEM has received results from the first two days of full time air quality monitoring at a stationary location in Conimicut. The monitor records the level of hydrogen sulfide in the ambient air. The monitor can record H2S levels from 2 to 90 parts per billion.


  • Although the results fluctuated, and sometimes were at non-detectable levels, they did show hydrogen sulfide at 90 parts per billion (90 ppb) or greater over a three hour period on Thursday morning, September 18. During a six-hour period on Thursday evening, levels fluctuated from close to 30 ppb to over 90 ppb. These findings exceed the level of 30 ppb at which federal guidelines recommend avoiding long-term exposure.


  • The fluctuating levels are thought to be associated with changing wind and tide conditions.


  • Based on these results, DEM will employ more monitoring devices in the area to track air quality at the shore and in residential areas.


  • DEM asks residents to report any continuing odor problems, and any suspected sources of those problems to DEM's office of Compliance and Inspection at 222-1360 during weekday hours, and to the Department's 24-hour emergency line, 222-3070 at night and on weekends.


  • An updated Health and Environmental Advisory from DEM and the RI Department of Health is being provided today to residents of the affected area via door-to-door distribution through the courtesy of Mayor Scott Avedesian's office.


  • Health recommendations, including recommendations to avoid exposure whenever possible, can also be found on the Department of Health website at www.HEALTH.ri.gov.
  • The Department is overseeing the removal and cleanup of the decaying organic matter that washed up along the shoreline. The matter - rotting seaweed covered by millions of tiny clamshells - is believed a primary source of the objectionable odors that have plagued the Conimicut neighborhood for the past two weeks. This morning, cleanup crews from DEM's emergency response contractor, in concert with the City of Warwick's Department of Public Works, began removing the material from the beach. The greatest concentration of the material was located near the intersection of Shawomet Ave. and Symond Street. The material is being incorporated into compost at the Warwick composting facility.


  • The configuration and shallowness of Conimicut Cove, combined with the northerly winds that have been occurring during the past several weeks, had essentially trapped a large mass of the decaying organic materials within the riprap and prevented it from washing out to sea. These unusual circumstances, combined with the public health concerns raised by the lingering odors, prompted DEM to initiate the cleanup action. Under normal conditions, tidal action, wind and waves would allow natural decomposition to occur, without the need for such intervention.


  • Air quality monitoring results from Friday and Saturday morning indicated levels near 30ppb during the day on Friday, with occasional peaks at 90 ppb or higher, but lasting no longer than 15 minutes each. Tests from Friday evening and Saturday morning registered 0-3 ppb or "trace levels" of hydrogen sulfide. DEM reported detecting a "faint" odor at two locations during a Saturday morning site visit. DEM also conducted a neighborhood monitoring Saturday morning using portable equipment at various locations and detected low levels of hydrogen sulfide.


  • Further air quality monitoring from 10:30 a.m. to noon on Saturday showed spikes in the level of hydrogen sulfide, up to 20 ppb. On Sunday morning and afternoon, and from 11 a.m. to noon today, hydrogen sulfide levels above 90 ppb were detected. Today's spike may be attributed to the removal action taking place in the area. Although the air monitor indicated readings above 90 ppb earlier today, odors were not detected at that time.


  • DEM will continue to monitor hydrogen sulfide levels in the neighborhood and undertake additional clean-up activity if necessary.


  • The public may report any continuing problems, and any suspected sources of those problems, to DEM's Office of Compliance and Inspections at 222-1360 (weekdays) or after hours/weekends at 222-3070. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • The removal and cleanup of the decaying organic matter that washed up along the shoreline continued today and will be completed tomorrow. So far, about two truckloads of the matter have been vacuumed from the beach by DEM's emergency response contractor, in concert with the City of Warwick's Department of Public Works. The greatest concentration of the material was located near the intersection of Shawomet Ave. and Symond Street. The material is being incorporated into compost at the Warwick composting facility.


  • Air quality testing has shown a marked decrease in hydrogen sulfide levels since the removal action began. Air monitoring was conducted during the vacuuming process, registering some elevated levels, which returned to lower levels upon completion of the vacuuming. On Monday, September 22, the day the cleanup began, hydrogen sulfide levels spiked to 15 ppb from 1:45 to 2:15 PM. The levels fluctuated from 0 to 3 ppb from 7:14 to 11:55 AM today, and hydrogen sulfide levels were at zero at all other times.


  • Dissolved oxygen results indicate normal levels in the area of the removal, which lends additional evidence that the hydrogen sulfide problem is related to the material that is washing ashore and not an off-shore water problem.


  • DEM will continue to monitor hydrogen sulfide levels in the neighborhood and undertake additional clean-up activity if necessary.


  • The public may report any continuing problems, and any suspected sources of those problems, to DEM's Office of Compliance and Inspections at 222-1360 (weekdays) or after hours/weekends at 222-3070. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • The removal and cleanup of the decaying organic matter that washed up along the shoreline was completed today.


  • Air quality testing continues to a show a marked decrease in hydrogen sulfide levels since the removal action began. In air monitoring conducted yesterday and today, Hydrogen sulfide levels were recorded at 2 ppb from 12:00 to 2:00 pm and from 3:00 to 5:00 pm on Tuesday, September 23rd. Hydrogen sulfide levels were at zero (0) at all other times.


  • DEM will continue to monitor hydrogen sulfide levels in the neighborhood and undertake additional clean-up activity if necessary.


  • The public may report any continuing problems, and any suspected sources of those problems, to DEM's Office of Compliance and Inspections at 222-1360 (weekdays) or after hours/weekends at 222-3070. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality testing on September 24th and 25th continues to show a marked decrease in hydrogen sulfide levels. Hydrogen sulfide levels were recorded at 2ppb from 1:30 to 2:00pm yesterday. Levels fluctuated from 0-2ppb from about 7:30 to 11:00 am today, and were at 0 at all other times.


  • The removal and cleanup of the decaying organic matter that washed up along the shoreline - namely, that portion deemed primarily responsible for the odors - was completed yesterday. DEM will continue to monitor hydrogen sulfide levels in the neighborhood and undertake additional clean-up activity if necessary.


  • DEM today received the results of swab samples taken on September 17 from the exterior surfaces of three houses in the Conimicut area (two on Shawomet Avenue and one on Bellman Avenue.) The samples were taken to try and determine the source of discoloration on some houses in the neighborhood, which some residents felt was linked to the recent odor problems. The results of the tests show the presence of various molds. The specific mold spores identified are as follows: Pollen, Curvularia, Ulocladium, Chaetomium, Mushroom, Bipolaris, Stemphyllium, Nigrospora, Penicillium/Aspergillus, Cladosporium, Pithomyces, and Ascospores. The number, types and quantity of molds found in the samples are considered by the laboratory to be consistent with normal exposure, especially in a wet (e.g. waterfront) environment and during a wet summer. The types of molds found in the samples are typically found on dead and decaying plant material. Therefore, the rotting organic matter thought to be the cause of the odor problems may have contributed to the onset or exacerbation of mold stains on some of the homes in the area.


  • DEM has consulted with the Department of Health about the mold. According to Health, it is very common for mold to grow on trees and houses (particularly on the north sides, and mold only presents a health concern when it is inhaled in a highly contaminated enclosed (i.e. indoor) environment. For more information on mold, its health effects, and how best to clean moldy surfaces, visit the Department of Health's website at www.health.ri.gov


  • The public may report any continuing problems, and any suspected sources of those problems, to DEM's Office of Compliance and Inspections at 222-1360 (weekdays) or after hours/weekends at 222-3070. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality testing on September 25 and 26 continued to show low hydrogen sulfide levels (6 to 11 ppb from 5:00 am to 7:30 am today; zero at all other times) until around noon today. At that time, the readings spiked - initially to 23 ppb and then to 90 ppb or greater for a brief period. By mid afternoon, the levels had again subsided.


  • Odors were reported at various times during the day, and were particularly noticeable at the time of the elevated readings.


  • A DEM inspector surveyed the beach area along the Conimicut shoreline this afternoon and observed significant amounts of decaying seaweed, left exposed by the low tide. Odors were noticeable at that time.


  • The exposed seaweed and other decaying matter, coupled with today's easterly breeze, are presumed to be the causes of the elevated hydrogen sulfide levels and associated odors.


  • DEM continues to coordinate its monitoring and response activities with the Department of Health, the Governor's Office, and Mayor Avidesian's Office.


  • DEM, in conjunction with its partners, plans to carefully track the hydrogen sulfide levels throughout the weekend and, if warranted, employ additional air monitoring equipment to assess levels in other portions of the neighborhood. Based on those results, the agencies will determine what, if any, additional steps should be taken to address the odor problem.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM after hours or over the week-end at 222-3070 to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality testing on September 27 and 28 showed low hydrogen sulfide levels during most of the weekend. From 2:40 to 6 a.m. Saturday the levels spiked to 90 ppb or greater, but then subsided. Hydrogen sulfide levels fluctuated from 0 to 2 ppb from 7 a.m. to noon on Sunday, and were at zero at all other times.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM after hours at 222-3070 to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality testing this week continues to show hydrogen sulfide levels at zero or just above zero. On October 1 & 2, levels were at zero on both days except from 7:30 to 8 a.m. yesterday, when they reached 1 ppb. On Tuesday, hydrogen sulfide levels were at zero throughout the day, except for a 45-minute period in the early morning when they reached 3 ppb.


  • The removal and cleanup of decaying organic matter along the Conimicut shoreline continued again this week. The Governor's Office was instrumental in obtaining additional assistance for the cleanup efforts through the Department of Corrections. On Tuesday at low tide, crews from Corrections raked up half a truckload of additional organic matter that had washed up along the beach. Although decaying vegetation is still present on the bottom of the Bay, area residents have reported that the volume of material has decreased. The decaying matter tends to surface and wash ashore during extremely low tides. Cleanup is scheduled to resume during the latter half of next week, during the moon tide.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM at 222-1360, or after hours at 222-3070, to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality testing from October 3 to 6 showed that hydrogen sulfide levels spiked to 3ppb from 12:30 to 2:30pm on Friday, October3. Hydrogen sulfide levels were at zero at all other times.


  • Winds have generally been from the west/northwest throughout the period. Extremely low/high tides are expected on Friday, October 10.


  • The removal and cleanup of decaying organic matter along the Conimicut shoreline is scheduled to resume during the latter half of this week, during the moon tide.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM at 222-1360, or after hours at 222-3070, to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality testing on October 6 & 7 showed that hydrogen sulfide levels spiked to 4ppb at 1 p.m. and to 2 ppb at 2 p.m. on Monday, October 6. Hydrogen Sulfide also spiked to 3ppb at 11:30am today when the DEM inspector took the readings. The inspector did not detect any odor and winds were variable and light at the time. These small spikes may be attributed to the low tide conditions near the time of the spikes. Hydrogen sulfide levels were at zero at all other times. No odors were detected.


  • Winds have generally been from the west/northwest throughout the period. Extremely low/high tides are expected on Friday, October 10.


  • The removal and cleanup of decaying organic matter along the Conimicut shoreline is scheduled to resume during the latter half of this week, during the moon tide.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM at 222-1360, or after hours at 222-3070, to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Hydrogen Sulfide levels spiked to 5ppb from 1:00-2:45am, to 3ppb from 4:00-5:15am, and to 2ppb from 8:00-9:00am on October 9. The levels were at zero at all other times on October 8 & 9.


  • A summary of low tides for the long weekend are as follows:

    Date A.M. P.M.
    Oct 10 (Fri) 1:34 a.m. 2:12 p.m.
    Oct 11 (Sat) 2:06 a.m. 2:47 p.m.
    Oct 12 (Sun) 2:40 a.m. 3:22 p.m.
    Oct 13 (Mon) 3:15 a.m. 3:59 p.m.

  • High Pressure moving in from Eastern Canada will bring us North to Northeast winds from Friday to Sunday. This may bring some higher levels over the weekend.


  • The removal and cleanup of decaying organic matter along the Conimicut shoreline is resumed today, during the moon tide.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM at 222-1360, or after hours at 222-3070, to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Air quality monitoring from Friday, October 10 through Monday, October 13 showed several spikes in hydrogen sulfide levels on October 10 and 11 that were attributed to Friday's extremely low tide and northeast winds. On October 10, hydrogen sulfide levels spiked to 37ppb from 1-2 p.m., 36ppb from 2-3:20p.m., 32ppb from 5:20-5:45p.m, and to 4ppb from 6-7 p.m. Levels also spiked to 2ppb for 15 minutes during the early morning hours on October 11. A hydrogen sulfide level of 2ppb was maintained throughout the period from 9 a.m. October 12 to 3 a.m. October 13.


  • Hydrogen Sulfide levels were at zero at all other times during the holiday weekend.


  • The removal and cleanup of decaying organic matter along the Conimicut shoreline continued on Thursday, October 9, during the moon tide.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM at 222-1360, or after hours at 222-3070, to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.
  • Although air quality monitoring conducted in the Conimicut area throughout early October continued to show only slight elevations of hydrogen sulfide, DEM continued its monitoring efforts through October 29 so that air samples could be taken during periods of astronomical low tides. Previous spikes in hydrogen sulfide levels in the area were attributed to extremely low tides. The monitoring showed that despite the prevailing low tides that occurred between October 14 and October 31, hydrogen sulfide levels were at zero during most of this time period. When hydrogen sulfide was detected, it was found only during brief intervals of time, with a maximum reading of five ppb.


  • The decrease in hydrogen sulfide levels is the result of several factors, including a reduction in the amount of decaying seaweed present in the area, cooler temperatures, and the onset of more seasonable wind from the south/southwest.


  • It is extremely unlikely that odor problems associated with hydrogen sulfide will continue through the winter. The amount of seaweed present in the area will continue to decrease, because a drop in both the water and air temperatures is not conducive for seaweed to grow or respire. Thus, the problem should subside and ultimately cease.


  • Public health recommendations relating to hydrogen sulfide exposure remain available on the Department of Health's website at www.health.ri.gov.


  • Residents can contact DEM at 222-1360, or after hours at 222-3070, to report any significant changes in conditions. For questions about general health concerns, contact the Family Health Information line at 800-942-7434. Callers may leave their name, number and a recorded message.

For General Information 222-6800 • After Hours Emergencies 222-3070 • Disclaimer
rev. 11/18/03