The Performance Analysis of Two Relatively Small Capacity Urban Retrofit Stormwater Controls
Bibliographic record
Abstract
This paper details field investigations that were conducted on the performance of small capacity urban retrofit stormwater control measures.The objective of the two year study (2013)(2014)(2015) was to provide performance data on stormwater retrofits that could not be fully sized according to conventional standards due to space constraints.In many states performance credits are not granted to stormwater management controls that are not designed to manage regionally derived water quality volumes.In retrofit applications there may exist numerous limitations to conventionally sized systems such as limited rights of way, setback distances or existing utilities.The larger scale objective of green infrastructure implementation is to improve receiving water quality and therefore even undersized systems, to some extent, meet this objective.This study introduces data on two systems: an innovative bioretention design with a water treatment residual amended filter media and an internal storage reservoir; and an undersized linear subsurface gravel wetland sized to optimize both phosphorus and nitrogen removal.The systems were retrofitted into existing developed areas and were sized at less than the water quality volume due to limited space at each location.The bioretention system (IBSC) was constructed in a commercial area in the town of Durham, NH in summer 2011 and the subsurface gravel wetland system (SGWSC) was constructed in a narrow drainage right of way in a residential neighbourhood of Durham, NH in the fall of 2013.Sediment and metal removals for both undersized systems were high with median removal efficiencies in the SGW of 75% for both total suspended solids (TSS) and total zinc (TZn).The Durham IBSC recorded median removal efficiency (RE) of 86% for TSS and TZn.Total phosphorus (TP) REs were higher than conventional bioretention systems with the subsurface gravel wetland system achieving a median RE of 53% and the Durham IBSC achieving a median RE of 40% for TP.Both systems reduced total nitrogen (TN) by approximately 20% (23% for SGWSC and 21% for Durham IBSC) with median effluent concentrations of 1.4 mg/L.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".