We present a sample of 34 weak metal line absorbers at z < 0.3 selected by the simultaneous > 3σ detections of the Si λ1260 and C λ1334 absorption lines, with W r (Si ) < 0.2 Å and W r (C ) < 0.3 Å, in archival HST /COS spectra. Our sample increases the number of known low-z "weak absorbers" by a factor of > 5. The column densities of H and low-ionization metal lines obtained from Voigt profile fitting are used to build simple photoionization models. The inferred densities and line of sight thicknesses of the absorbers are in the ranges of −3.3 < log n H /cm −3 < −2.4 and ∼1 pc -50 kpc (median ≈ 500 pc), respectively. Most importantly, 85% (50%) of these absorbers show a metallicity of [Si/H] > −1.0 (0.0). The fraction of systems showing near-/super-solar metallicity in our sample is significantly higher than in the H -selected sample (Wotta et al. 2016) and the galaxy-selected sample (Prochaska et al. 2017) of absorbers probing the circum-galactic medium at similar redshift. A search for galaxies has revealed a significant galaxy-overdensity around these weak absorbers compared to random positions with a median impact parameter of 166 kpc from the nearest galaxy. Moreover, we find the presence of multiple galaxies in ≈ 80% of the cases, suggesting group environments. The observed dN/dz of 0.8 ± 0.2 indicates that such metal-enriched, compact, dense structures are ubiquitous in the halos of low-z group galaxies. We suggest that these are transient structures that are related to galactic outflows and/or stripping of metal-rich gas from galaxies.

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