Download All Saints Catholic Church

Stormwater Management Report
For
All Saints Catholic Church
Stormwater Management Improvement Project
2443 Mount Vernon Road
Dunwoody, Georgia 30338
Parcel # 18-0349-003-01
Issue Date: April 15, 2015
Prepared By:
Cornerstone Site Consultants, LLC
2985 Gordy Parkway, Suite 119
Marietta, GA 30066
Project #: 2014-0001
Hydrology Study Conclusion The report provided a stormwater analysis of the existing conditions, post developed conditions, downstream and on‐site storm sewer system for the All Saints Catholic Church master plan. Water quality measures for the existing and new impervious roof and parking areas are treated by Crystal Stream Water Quality units. The channel protection storage volume is provided in underground detention pond pipes along with the stormwater detention. There is a reduction in the peak flowrates to the downstream study point. On‐site storm sewer pipe systems were designed to provide capacity for the 100 year peak flow runoff rate design storm. Based on the information provided in this report, the proposed stormwater management improvements for the All Saints Catholic Church meet the applicable City of Dunwoody stormwater design regulations. Net effect: The four new underground stormwater detention pipe systems will store stormwater runoff from both the existing and future buildings, and parking areas and facility; and then release the stormwater at a much slower rate than the existing stormwater runoff from the existing parking lots. The net effect is that the stormwater released from the detention pond systems will be at the same release rate as if the church property was all a natural forest and vegetation. This will reduce the stormwater runoff rate to the nearby streams. In addition, the four new underground stormwater detention systems will each contain a water quality treatment device. This device will filter out sediment and pollutants from the stormwater runoff and improve the water quality of the stormwater runoff from the church property. Therefore, the proposed stormwater detention systems will significantly reduce the stormwater runoff rate and improve the quality of the stormwater runoff from the church.