15.18.04.05

.05 Compost Classification.

A. A compost product is classified as a General Use, Limited Use, or Restricted Use compost as shown in §§B—D of this regulation.

B. General Use Compost.

(1) General Use compost may not exceed the following specifications:

Parameter Parameter Limit
All limits apply to
product leaving
composting facility.
(a) pH (range) 6.0—8.0
(b) Heavy metals (maximum)
(i) Arsenic 41 mg/kg dry wt.
(ii) Cadmium 39 mg/kg dry wt.
(iii) Chromium 1200 mg/kg dry wt.
(iv) Copper 1500 mg/kg dry wt.
(v) Lead 300 mg/kg dry wt.
(vi) Mercury 17 mg/kg dry wt.
(vii) Molybdenum 18 mg/kg dry wt.
(viii) Nickel 420 mg/kg dry wt.
(ix) Selenium 36 mg/kg dry wt.
(x) Zinc 2800 mg/kg dry wt.
(c) PCBs 5 ppm
(d) Man-made inerts (maximum)
>4mm, <13mm
2 percent dry wt.
(e) Film plastic >4mm 2 percent dry wt.
(f) Process to further reduce
pathogens (required for compost from municipal
solid waste or manure)
pass

(2) A General Use compost:

(a) Shall pass through a 12mm (1/2 inch) screen;

(b) Shall be stabilized;

(c) May not have an objectionable odor; and

(d) May be distributed as a soil conditioner for use by the general public or for any use allowed by this chapter.

C. Limited Use Compost.

(1) A Limited Use compost may not exceed the following specifications:

Parameter Parameter Limit
All limits apply to
product leaving
composting facility.
(a) pH (range) 6.0—8.0
(b) Heavy metals (maximum)
(i) Arsenic 41 mg/kg dry wt.
(ii) Cadmium 39 mg/kg dry wt.
(iii) Chromium 1200 mg/kg dry wt.
(iv) Copper 1500 mg/kg dry wt.
(v) Lead 300 mg/kg dry wt.
(vi) Mercury 17 mg/kg dry wt.
(vii) Molybdenum 18 mg/kg dry wt.
(viii) Nickel 420 mg/kg dry wt.
(ix) Selenium 36 mg/kg dry wt.
(x) Zinc 2800 mg/kg dry wt.
(c) PCBs 10 ppm
(d) Man-made inerts (maximum)
>4mm
4 percent dry wt.
(e) Film plastic >4mm 2 percent dry wt.
(f) Process to further reduce
pathogens (required for compost from municipal
solid waste or manure)
pass

(2) A Limited Use compost:

(a) Shall pass through an 18mm (3/4 inch) screen;

(b) Shall be stabilized;

(c) May not have an objectionable odor; and

(d) May only be distributed for use by a commercial, agricultural, institutional, or governmental operation, or for restricted use as provided by this chapter.

D. Restricted Use Compost:

(1) A Restricted Use compost may not exceed the indicated maximum level for any heavy metal or trace element, as follows:

(a) Arsenic 75 mg/kg dry wt.
(b) Cadmium 85 mg/kg dry wt.
(c) Chromium 3000 mg/kg dry wt.
(d) Copper 4300 mg/kg dry wt.
(e) Lead 840 mg/kg dry wt.
(f) Mercury 57 mg/kg dry wt.
(g) Molybdenum 75 mg/kg dry wt.
(h) Nickel 420 mg/kg dry wt.
(i) Selenium 100 mg/kg dry wt.
(j) Zinc 7500 mg/kg dry wt.

(2) A Restricted Use compost:

(a) May not be a hazardous waste, as defined in COMAR 26.13.02.03;

(b) May not be stockpiled or disposed of unless authorized by the Maryland Department of the Environment;

(c) May not be distributed or sold to the general public;

(d) Is restricted to distribution for use as a final, intermediate, or alternate daily landfill cover, as provided by COMAR 26.04.07, or on marginal land or in land reclamation efforts if applied at rates not to exceed limits established in Table 2 of Regulation .12 of this chapter; and

(e) Includes any compost exceeding any parameter limit for Limited Use compost, as provided in Regulation .05C of this chapter, or any compost designated by the registrant as Restricted Use classification.