Martin Marietta seeks Sunflower Quarry expansion; commissioners and neighbors raise blasting, dust and growth concerns

Sean Penley, county planning staff, presented an application from Martin Marietta Kansas City LLC for an amendment to the conditional use permit authorizing continued operation and expansion of Sunflower Quarry (application w24-436‑cup). The quarry site is on leased property totaling about 885 acres; current permitted quarry limits total roughly 353 acres. The applicant proposes expanding the permitted mining area to the east by about 40.57 acres (labeled 2NEE in staff maps). Martin Marietta requested a 10‑year term for the amended permit.

Penley told the Board that the quarry’s first CUP was approved in 1991, with four renewals since. He said the 2020 CUP allowed an additional 53 acres and set a five‑year term with a five‑year renewal; Martin Marietta now requests the current amendment because rock demand in the area is exceeding earlier projections. Planning staff said the proposed expansion meets or exceeds required setbacks: county rules require minimum setbacks of 750 feet to the nearest property line and 1,000 feet to the nearest residence; staff said the proposed expansion would be about 1,343 feet from the closest residence.

Penley described the quarry’s reclamation program, including a stipulation to reclaim one acre for every two acres disturbed; staff said Martin Marietta is exceeding that reclamation ratio and provides an annual reclamation status map and a reclamation bond or letter of credit. He said the operator holds required blasting permits and county staff conducts annual inspections.

Neighbors who attended the West Consolidated Zoning Board hearing raised concerns about blasting-related ground vibration, air blast noise, dust and the expansion drawing the quarry closer to residences along Kill Creek Road and 97th/111th. Penley said those issues were similar to concerns raised in 2020. He said Martin Marietta has implemented mitigation including smaller blast charges and practices designed to reduce vibration and air blast and that the operator was blasting below even the county’s usual thresholds because of CUP stipulations that impose lower limits.

Commissioners asked several questions: why staff recommended a 10‑year term when prior permits were typically five years; whether reclaimed quarry land would be suitable for development (staff said reclamation may create open space, wetlands or water bodies and that building on reclaimed quarry areas would require foundation and compaction work and be subject to permitting); and how annexation by the City of DeSoto to the north affects future land use (staff said the city was notified and had no current concerns). Penley noted that the West Consolidated Zoning Board recommended approval 5–2 with the stipulations in the resolution. The item will return to the board for action at the Jan. 23 business session; no final vote was recorded in the Jan. 16 agenda review transcript.