Audit Report on the on the Department of Environmental Protection’s Maintenance of Rain Gardens

The New York City (NYC) Department of Environmental Protection’s (DEP’s) mission is to safeguard public health and the environment by supplying clean drinking water, collecting and treating wastewater, and reducing air, noise, and hazardous materials pollution. DEP is required to reduce stormwater runoff to improve the water quality in waterbodies surrounding NYC pursuant to the Consent Order by the New York State Department of Environmental Conservation (NYS DEC). In connection with that requirement, DEP’s Bureau of Environmental Planning and Analysis (BEPA) plans and implements various green infrastructure projects, including rain gardens (formerly known as bioswales), under the NYC Green Infrastructure Program (GI Program), and maintains all related information. DEP is responsible for overseeing the construction of more than 2,500 rain gardens on City owned property such as streets, sidewalks, schools and public housing to reduce the volume of stormwater runoff that enters the City’s sewer system. DEP’s Bureau of Water and Sewer Operations (BWSO) is responsible for the maintenance of each rain garden under DEP’s jurisdiction, after construction and any applicable guarantee period in which the construction contractor maintains it under the terms of its contract with the City.

Overall, rain gardens do an important job of keeping the City’s waters clean and improving street aesthetics. In order to do their job properly and retain their appearance, rain gardens need regular maintenance to ensure that they are functioning properly to effectively capture stormwater runoff, thereby helping to reduce the amount of pollution that enters the City’s waterbodies. According to DEP, rain gardens are valuable green infrastructure assets that help keep stormwater out of local sewers, improve street drainage, purify air, reduce temperatures during hot weather, and reduce puddles and ponds.

Rain gardens contain plants and engineered soil that have been horticulturally designed to absorb large amounts of stormwater, thereby reducing the amount of water that enters the sewer system. To help ensure that the rain gardens for which it is responsible are appropriately maintained, DEP created the Rain Garden Maintenance Manual (Manual). The Manual serves as a guidebook for DEP/BWSO’s maintenance personnel and provides a thorough description of the various types of maintenance tasks, procedures and equipment that are required to maintain the rain gardens’ appearance and ensure that they are functioning properly.

Once a rain garden’s construction is completed, it remains under a guarantee provided by the contractor who installed it. The guarantee period normally spans one to two years during which time the contractor is responsible for performing regular maintenance as stipulated in the contract. Once DEP accepts the rain garden, at or after the expiration of the guarantee period, the rain garden is deemed to be under DEP’s sole jurisdiction. At that point, within DEP, responsibility for maintenance of the rain garden is assigned to BWSO for what DEP refers to as “full maintenance.” While under full maintenance by DEP, BWSO is responsible for providing maintenance services to the rain gardens one to two times each week, according to the Manual. DEP’s maintenance locations are broken down into 18 routes in 31 zones throughout the City.

During the audit scope period, as of April 17, 2018, BWSO was responsible for full maintenance of 805 rain gardens in four boroughs and employed a full-time staff of approximately 36, including 3 Gardener-Level IIs (G2s), oversight employees with overall responsibility for the maintenance of all DEP rain gardens in their assigned areas, 8 supervisors known as Gardener-Level Is (G1s), responsible for directing and performing hands-on maintenance with BWSO’s 8 maintenance teams, each generally consisting of 4 to 8 workers. During the period we audited, DEP supplemented the maintenance staff with between 30 and 63 seasonal workers.

According to the BWSO records, as of April 17, 2018, a total of 2,511 rain gardens, at an estimated cost of just over $100 million, had been constructed within the four Boroughs that were either under a contractor guarantee or in full maintenance. Of the 2,511 rain gardens on BWSO’s spreadsheet, BWSO was responsible for the full maintenance of 805 in 4 of the 5 boroughs as shown below:

According to the data provided by DEP, in Fiscal Year 2017, the total expenditure for the rain gardens’ maintenance, including staffing salaries with fringe benefits (both permanent and seasonal), general supplies and other related services, was $4.23 million and in Fiscal Year 2018 it was $5.91 million. For Fiscal Year 2019, as of May 21, 2019, that expenditure was $5.24 million.

This audit determined whether DEP adequately maintains the 805 rain gardens under its jurisdiction in accordance with the Manual.

Audit Findings and Conclusion

Our audit found multiple areas of weakness in DEP’s maintenance of its rain gardens. These weaknesses need to be addressed to better ensure that City-constructed rain gardens continue to effectively capture stormwater runoff and help reduce the amount of pollution that enters into the City’s waterbodies, clean the air, and beautify the City’s neighborhoods.

Of the 102 sampled DEP rain gardens that we inspected in Brooklyn, Queens, and the Bronx, which cost the City more than $4 million to construct, we found that the majority were not sufficiently maintained to ensure their proper functioning and appearance. That determination was based on our visual inspection of each sampled rain garden for conditions that DEP’s Manual identifies as indicators of whether a rain garden is being properly maintained. Such conditions include: the amount of litter and debris present; the presence of sediment in the gravel strips, soil beds, or curb cuts in quantities that could impede water flow and absorption; and the condition of the plants, including whether weeds were growing. These are all factors that affect the system’s capacity to manage stormwater effectively and to maintain an appropriate appearance.

Specifically, 67 of the 102 sampled DEP rain gardens (66 percent) were affected by two or more conditions that DEP’s Manual states can impair a rain garden’s functionality, and 53 of the sampled rain gardens (52 percent) exhibited two or more unsightly conditions, also cited in DEP’s Manual as factors that detract from a rain garden’s appearance and may signal to the community that the site is under-maintained. Overall, 30 of DEP’s sampled rain gardens (29 percent) exhibited 4 or more deficient conditions, and 7 sampled rain gardens were found to be fully maintained in accordance with DEP Manual standards, having no visible deficiencies, and well-maintained tree guard rails and curbs, at the times of our inspections.

Further, and apart from the abovementioned conditions involving functionality and appearance, we observed damaged or sinking tree guard rails at eight rain gardens, damaged or sinking curbs bordering six rain gardens, and one rain garden with both of those conditions. Proper maintenance of tree guards and curbs is essential for protecting the rain gardens and for the safety of pedestrians.

We also found that the BWSO’s maintenance logs for many of the sampled rain gardens were incomplete, inaccurate, and ineffective as a management tool for monitoring their condition and maintenance needs. Among other things, we found conditions such as hardscape (tree guards, curbs, concrete) damage, weed growth, sediment accumulation, and missing trees and plants that were not corrected or correctable during routine maintenance. Further, we found that these conditions were not accurately recorded in the logs that would have alerted responsible officials that the conditions remained in need of correction. Moreover, the recording of routine maintenance data on the BWSO’s maintenance logs—such as the dates on which trash, weeds, and sediment were reportedly removed—was not always consistent with our contemporaneous observations made during audit inspections of the same rain gardens. In addition, the maintenance logs showed—without any recorded explanation—that some rain gardens in our sample did not receive any routine maintenance during a three-week period that coincided with our visual inspections of those sites. The absence of such maintenance contravenes the Manual’s standard that requires one- to two-maintenance visits per week for each rain garden. Consequently, DEP management cannot fully rely on BWSO’s maintenance logs to accurately account for the condition of the agency’s rain gardens and assess the adequacy, efficiency, and effectiveness its maintenance staffing and operations.

Audit Recommendations

This report makes a total of 18 recommendations, including that DEP should:

• Perform required maintenance in accordance with the Manual, at every rain garden, to maintain each rain garden’s appearance and proper functioning.
• Ensure that G1 supervisors examine each rain garden after they and their crews have performed maintenance and that they prepare, review, and initial each maintenance log to indicate that it has been accurately and properly completed with all necessary information, including both the tasks they performed and the follow-up maintenance and repair work, if any, that the rain garden still requires to address conditions that need further attention.
• Establish performance targets for G2s to increase their field visits to independently assess and record the condition of the rain gardens they oversee, verify the G1s’ maintenance log-reports, and follow up to address deficient conditions in the rain gardens and document those efforts.
• Ensure that the metal tree guard rails and curbs surrounding the rain gardens that were found either damaged or sinking at the locations cited in this report have been fixed.
• Incorporate and/or enhance community engagement as an alternative or supplemental means for improving rain gardens maintenance. In that regard,
  • Consider, partnering with the Department of Sanitation and City-contracted business improvement districts to better assess neighborhoods where trash and litter in rain gardens is a persistent problem and identify special events that should trigger additional cleaning.
  • Conduct community outreach to enlist community input and support to raise awareness on best practices, including the proper disposal of litter and the types of issues to report to DEP through 311, to maintain and improve the appearance and functioning of the rain gardens.
  • Consider approaching or partnering with businesses, home owners, institutions, and community associations to adopt rain gardens.
• Ensure that maintenance records of all rain garden sites are complete and accurate.
• Establish protocols for verification and quality control of rain garden maintenance data.
• Document the existence of each maintenance issue every time the rain garden site is visited, until the issue is resolved, so that a record of how long the condition has existed and the time taken to correct each of the various issues can be tracked.
• Revise the maintenance logs so that all nine of the required maintenance tasks prescribed by Section 6 of the Manual are included as part of the routine maintenance checklist. In connection with that revision, designate codes to capture conditions of the tree guard rails and curbs in and surrounding the rain garden.
• Use photographs to document “before and after” conditions observed each time a rain garden receives maintenance, routine or otherwise, by a DEP maintenance team.
• Use the collected maintenance data for management analyses to aid in troubleshooting maintenance issues (such as trash, planting, soil health and permeability) and for maintenance program refinements.
• Install rain garden ID tags with appropriate control number to effectively address maintenance needs reported by the public, effectively communicate with contractors, and for an additional efficiency measure when DEP deploys its planned technology solution.

Agency Response

In its response, DEP stated that it “agrees with, and has largely implemented most of the recommendations contained in the Report” but also stated that it disagrees with 3 of the 18 recommendations (Recommendations # 14, 15, and 18). Of the remaining 15 recommendations, DEP responded directly to 2 (# 2 and 3), and indicated general agreement with, but did not provide a direct response to the remaining 13.

In addition, DEP stated, “We have reviewed the Report and have significant concerns with the report’s findings and recommendations.” In that regard, DEP commented on several specific statements in the report. DEP’s comments are further described and discussed in the Discussion of Audit Results section of this report.