T.F. Green Airport Improvement Program - FEIS Chapters - PVD

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) EvaluationTable 5-118 Annual Pollutant Loading by Drainage Area 1 (Alternative B4)Pollutant 2 (mg/l)Drainage Area TSS P N Cu Pb Zn BOD COD BacteriaPercentageChange fromNo-ActionBuckeye Brook North 46,346 77 711 0 11 16 2,472 30,897 525,256 0.6%Warwick Pond 2,123 4 33 0 0 1 113 1,415 24,060 13.5%Buckeye Brook South 35,507 59 544 0 8 12 1,894 23,671 402,413 1.2%Mill Cove (cumulative) 3 83,976 140 1,288 1 20 29 4,479 55,984 951,729 1.2%Tuscatucket Brook 12,184 20 187 0 3 4 650 8,122 138,080 11.0%Callahan Brook 8,596 14 132 0 2 3 458 5,731 97,424 -12.9%Brush Neck Cove (cumulative) 4 20,780 35 319 0 5 7 1,108 13,853 235,505 -0.3%Total 104,756 175 1,606 1 24 36 5,587 69,837 1,187,234 0.9%Source: VHB, Inc. TSS = Total Suspended Solids, P = Phosphorus, N = Nitrogen, Cu = Copper, Pb = Lead, Zn = Zinc, BOD = Biological Oxygen Demand, andCOD = Chemical Oxygen Demand.1 A Highway Land Use Category was assumed the most appropriate Land Use Category for T.F. Green to determine the Event Mean Concentrations (EMCs)values. Other categories include Residential, Commercial, Industrial, and Undeveloped/Rural.2 The pollutants loading listed in this table represent the potential annual loading rate for the five drainage areas, totaling 1,360 acres, without the installation ofstormwater BMPs. Pollutants were calculated using the Simple Method (Schuster, 1987) which requires estimates of annual rainfall, site impervious cover, landuse type, and pollutant loading coefficients based on land use. Totals are rounded.3 The Mill Cove drainage area consists of the combined Buckeye Brook North, Warwick Pond, and Buckeye Brook South drainage areas evaluated in this analysis.4 The Brush Neck Cove drainage area consists of the combined Tuscatucket Brook and Callahan Brook drainage areas evaluated in this analysis.Alternative B4 would decrease the amount of pollutant loading by 0.3 percent in the Brush Neck Covewatershed, improving water quality by removing potential pollutant sources. The 1.2 percent increase topollutant loads in the Mill Cove watershed would include mitigation measures designed to meet statestormwater requirements and therefore would not adversely affect water quality.The use of glycol for aircraft deicing would be the same as for Alternative B2 and is discussed in the impactassessment for Alternative B2. As a result of increased operations, Alternative B4 would increase the amount ofglycol used for deicing departing aircraft. However, with the glycol blending facility and proposed new deicermanagement system (both constructed as part of the No-Action Alternative), the use and discharge of glycolwould not substantially increase.Indirect ImpactsAlternative B4 would not result in any net change to the total area of roadways and parking within the GreenwichBay watershed. The majority of the increases in impervious surfaces for Alternative B4 are not from new roadways orparking areas, but are the result of new runway, taxiway, and building areas. All new roadways and parking areaswould include mitigation measures that would improve downstream water quality proportional to the new 4.5 acresof roadway and parking areas and would reduce potential pollutant loading to receiving streams (Table 5-117).Alternative B4 would therefore not result in adverse indirect impacts to the coastal watershed.Significant Impacts: Alternative B4 would not result in significant impacts to water quality. Increases inimpervious surfaces would be mitigated for Alternative B4 through the design of a stormwater managementsystem developed in compliance with regulatory standards.Chapter 5 - Environmental Consequences 5-219 July 2011\\mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH05_Environmental_Cons_JUL_2011.doc