Stormwater quantity and quality in a multiple pond-wetland system: Flemingsbergsviken case study

This study aims at presenting a methodology for quantifying yearly and monthly material transport into and out of stormwater treatment facilities (STFs) and at presenting problems related to monitoring and estimation of reduction efficiency. The model developed uses a sub-watershed approach. It employs standard values of runoff coefficients and pollutant concentrations together with precipitation data and estimated areas of different land uses within sub-watersheds. Both standard concentrations and field sampling data show that the inflow water to the facilities at Flemingsbergsviken is nutrient rich. The metal concentrations of lead, copper and zinc are relatively low, but may nevertheless increase the risk for negative impacts on aquatic life. The monthly values of runoff coefficients, used to estimate the monthly runoff water flow, vary largely between years and months. This makes the estimation of flow uncertain. A comparison of standard concentrations with measurements shows good correlation for nitrogen. The standard concentrations of total phosphorus and metals were higher than most of the sampled concentrations. However, the sampled concentrations are uncertain since they have been sampled instantaneously. An improved strategy concerning monitoring is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.