Time filter

Source Type

Parkway, MD, United States

Newcomer Johnson T.A.,The Interdisciplinary Center | Newcomer Johnson T.A.,National Oceanic and Atmospheric Administration | Kaushal S.S.,The Interdisciplinary Center | Mayer P.M.,U.S. Environmental Protection Agency | And 2 more authors.
Biogeochemistry | Year: 2014

Restoring urban infrastructure and managing the nitrogen cycle represent emerging challenges for urban water quality. We investigated whether stormwater control measures (SCMs), a form of green infrastructure, integrated into restored and degraded urban stream networks can influence watershed nitrogen loads. We hypothesized that hydrologically connected floodplains and SCMs are “hot spots” for nitrogen removal through denitrification because they have ample organic carbon, low dissolved oxygen levels, and extended hydrologic residence times. We tested this hypothesis by comparing nitrogen retention metrics in two urban stream networks (one restored and one urban degraded) that each contain SCMs, and a forested reference watershed at the Baltimore Long-Term Ecological Research site. We used an urban watershed continuum approach which included sampling over both space and time with a combination of: (1) longitudinal reach-scale mass balances of nitrogen and carbon conducted over 2 years during baseflow and storms (n = 24 sampling dates × 15 stream reaches = 360) and (2) 15N push–pull tracer experiments to measure in situ denitrification in SCMs and floodplain features (n = 72). The SCMs consisted of inline wetlands installed below a storm drain outfall at one urban site (restored Spring Branch) and a wetland/wet pond configured in an oxbow design to receive water during high flow events at another highly urbanized site (Gwynns Run). The SCMs significantly decreased total dissolved nitrogen (TDN) concentrations at both sites and significantly increased dissolved organic carbon concentrations at one site. At Spring Branch, TDN retention estimated by mass balance (g/day) was ~150 times higher within the stream network than the SCMs. There were no significant differences between mean in situ denitrification rates between SCMs and hydrologically connected floodplains. Longitudinal N budgets along the stream network showed that hydrologically connected floodplains were important sites for watershed nitrogen retention due to groundwater–surface water interactions. Overall, our results indicate that hydrologic variability can influence nitrogen source/sink dynamics along engineered stream networks. Our analysis also suggests that some major predictors for watershed N retention were: (1) streamwater and groundwater flux through stream restoration or stormwater management controls, (2) hydrologic residence times, and (3) surface area of hydrologically connected features. © 2014, Springer International Publishing Switzerland.

Wu W.,AKRF Inc.
41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 | Year: 2012

Construction activity generates some of the most disruptive noise in New York City. Noise generated by construction and construction equipment is regulated by the New York City Noise Code. This code requires the adoption and implementation of a noise mitigation plan for each construction site. In response to the Noise Code, AKRF, Inc. has been developing and implementing noise analysis methodology for assessing construction noise impacts since 2007. This paper introduces a useful method for noise assessment within Environmental Impact Statements (EIS) in accordance with the New York City Environmental Quality Review (CEQR) Technical Manual. Various mitigation measures in accordance with the Noise Code regulations are also discussed, and noise analysis results for several large-scale construction projects in New York City are presented. The results indicate that the methodology is effective for assessing construction noise impacts, and the mitigation measures are practical and feasible. The method and mitigation measures discussed may be useful in assessing and minimizing or eliminating noise impacts of projects proposed within metropolitan areas.

Sachwald B.H.,AKRF Inc.
24th National Conference on Noise Control Engineering 2010, Noise-Con 10, Held Jointly with the 159th Meeting of the Acoustical Society of America | Year: 2010

Urban areas are typically associated with high noise levels. With a population of more than eight million and growing, New York City is one of the largest cities in the world. In New York City, because of the population density and the wide variety of land uses (ex: residential, commercial, transportation, manufacturing and industrial) that exist in close proximity, it is common for a residential building to be located in an area with ambient noise levels that would be considered unsuitable for residential use. To protect inhabitants of a planned building to be located in an area with high ambient noise levels, an (E) designation or a Restrictive Declaration may be used to ensure that the building's interior environment meets a certain acoustical design criterion. In this paper, the (E) designation is defined, its regulatory process is outlined, the acoustical design criterion is discussed, and examples of common mistakes for noise (E) designation projects are listed.

Weinstein M.P.,New Jersey Institute of Technology | Litvin S.Y.,Stanford University | Krebs J.M.,AKRF Inc.
Ecological Engineering | Year: 2014

Although the importance of ecosystem services associated with estuarine wetlands and their functional linkages to other estuarine habitats have been increasingly recognized in the past 60 years, the approach to "restoration" and "rehabilitation" of degraded wetland habitats has largely lacked the application of systems thinking and scientific rigor and has resulted in a "disconnect" between the science and practice of wetland restoration. Examples of coastal wetland restoration science are discussed in the context of wetland functions that promote secondary production, ecological fidelity and their "connectedness" to both adjacent waters and the coastal zone. A means to integrate restoration science and practice to inform policy, and the quantification of restored functions in a systems framework is also described in the context of a sample case history. © 2013 Elsevier B.V.

Construction noise is one of the most disruptive noise sources in New York City. Large-scale projects especially can take more than a decade to complete, and often be located in areas with various sensitive noise receptors. A technological and reliable approach is required for evaluation of the construction noise and its impact in close proximity. This paper addresses construction noise analysis methods and mitigations, along with a case of noise study (i.e., Fordham University Lincoln Center), in accordance with the CEQR Technical Manual requirements and the New York City Noise Control Code regulations. Analysis methods (i.e., screening, detailed, and refined analyses) for construction noise assessment were introduced, and various construction mitigation options (i.e., source, path, and receiver measures) were examined and developed. The results indicated that the analysis methods were effective to assess noise impacts for large complicated construction projects, the mitigation measures were practical, and noise impacts at adjacent sensitive noise receptors were minimized or eliminated. The relevant experiences learned from the study may be beneficial for use of appropriate analysis methods and practical mitigation measures for large-scale construction projects in high-density urban environments.

Discover hidden collaborations