OPSS aggregates

Of the standard granular materials in the standard OPSS.MUNI 1010 only Granular O is recommended as a substitute for clear stone.

Where Granular O is substituted for clear stone in underground reservoir structures, the void ratio used in design calculations shall be 0.3 unless laboratory testing proves otherwise.

Examples of BMPs with underground reservoirs include Underdrains, infiltration trenches, permeable paving, infiltration chambers, exfiltration trenches.

Granular B type II and Select Subgrade Material (SSM) must be avoided in all LID structures. Both of these materials are permitted to have a higher proportion of undesirable fines in the distribution.

Justification

Grain size analysis, percent passing

Sieve size (mm)	A		B type I		B type II		B type III		M		O		SSM
	High	Low	High	Low	High	Low	High	Low	High	Low	High	Low	High	Low
150			100	100			100	100					100	100
106					100	100
37.5											100	100
26.5	100	100	50	100	50	100	50	100			95	100	50	100
19	85	100							100	100	80	95
13.2	65	90							75	95	60	80
9.5	50	73					32	100	55	80	50	70
4.75	35	55	20	100	20	55	20	90	35	55	20	45	20	100
1.18	15	40	10	100	10	40	10	60	15	40	0	15	10	100
0.3	5	22	2	65	5	22	2	35	5	22			5	95
0.15		15											2	65
0.075	2	8	0	8	0	10	0	8	2	8	0	5	0	25
d60	13	6	35	0.25	25	6	40	1.2	10	5	15	7	35	0.15
d10	0.7	0.1	1	0.08	1.2	0.075	1.2	0.085	0.6	0.09	2.5	0.3	1.2	NN
Content Uniformity	19	60	35	3	21	80	33	14	17	56	6	23	29
Void ratio (Vukovic)	0.26	0.26	0.26	0.40	0.26	0.26	0.26	0.27	0.27	0.26	0.34	0.26	0.26
Mean void ratio (Vukovic)	0.26		0.33		0.26		0.26		0.26		0.3		0.26
K(Hazen)(mm/hr)	1764	36	3600	23.04	5184	20.25	5184	26.01	1296	29.16	22500	324	5184	NN
Mean K(hazen)(mm/hr)	900		1812		2602		2605		663		11412		NN

Void ratios were calculated based on the coefficient of uniformity (C_U): $V_{R}=0.255\left(1+0.83^{C_{U}}\right)$ Where coefficient of uniformity is the ratio of the 60th and 10th percentile grain sizes: $C_{U}={\frac {d_{60}}{d_{10}}}$

Permeability (K) was estimated from the 10th percentile grain size using the Hazen formula.

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Gravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices.

Gravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices.

The void ratio (e) of a mixture is the ratio of the volume of void-space to the volume of solids. It is closely related to the concept of porosity (n) where porosity is the ratio of the volume of void-space to the total or bulk volume of the mixture. e = Volume of voids/Volume of solids = n/(1-n)

Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

Soil particles with a diameter less than 0.050 mm.

The void ratio (e) of a mixture is the ratio of the volume of void-space to the volume of solids. It is closely related to the concept of porosity (n) where porosity is the ratio of the volume of void-space to the total or bulk volume of the mixture. e = Volume of voids/Volume of solids = n/(1-n)

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

A parameter that describes the capability of a medium to transmit water.

The porosity (n) of a mixture is the ratio of the volume of void-space to the total or bulk volume of the mixture. It is closely related to the concept of void ratio (e) where void ratio is the ratio of the volume of void-space to the volume of solids. n = Volume of voids/Total volume of mixture = e/(1+e)