2007

The source for the Twin Ridge water supply is five wells located off Culver Street in Plaistow, NH.  Well # 2 is located 200 feet east of the pump station.  Well # 3 is located 300 feet northeast of the pump station.  Well # 4 located 63 feet southwest of the pump house.  Well # 5 is located 114 feet southeast of the pump station.  Well # 6 is located 210 feet northeast of the pump house.  Treatment consist of manganese green sand filtration to remove iron and manganese, ion exchange softeners to reduce water hardness, chlorine addition to kill bacteria, aeration to reduce radon, and sodium hydroxide to raise the pH to optimize iron and manganese removal and aid in corrosion control.
TWIN RIDGE
EPA # 1932050
Inorganic Contaminants	Units	MCLG	MCL	Average Level Detected	Range	Date	Violation Yes/No	Typical Source of Contaminant
Barium	ppm	2	2	0.029	0.029	2006	NO	Discharge from drilling wastes; discharge from metal refineries; erosion of natural deposits
Fluoride	ppm	4	4	1.71	1.18 to 2.45	2006	NO	Erosion of natural deposits
Volatile Organic Contaminants	Units	MCLG	MCL	Level  Detected	Range	Year	Violation Yes/No	Typical Source of Contaminant
Total Trihalomethanes (TTHMs)	ppb	0	80	8.4	n/a	2006	NO	By-product of drinking water chlorination.
Haloacetic Acids (HAA5)	ppb	0	60	2.0	n/a	2004	NO	By-product of drinking water chlorination.
Volatile Organic Contaminants	Units	MRDLG	MRDL	Average Level  Detected	Range	Year	Violation Yes/No	Typical Source of Contaminant
Chlorine	ppm	4	4	0.38	0.2 to 0.7	2006	NO	Water additive used to control microbes
Radiological Contaminants	Units	MCLG	MCL	Level Detected	Range	Date	Violation Yes/No	Typical Source of Contaminant
Gross Alpha (Compliance)	pCi/L	0	15	2.1	nd - 2.1	2005	NO	Erosion of natural deposits
Combined Radium	pCi/L	0	5	0.5	0.1 to 0.5	2005	NO	Erosion of natural deposits
Uranium	ppb	0	30	7.2	6.6 to 7.2	2005	NO	Erosion of natural deposits
Radon	pCi/L	Not Regulated		5,560	4,060 to 5,560	2005	n/a	Erosion of natural deposits
Radon is a radioactive gas that you can't see, taste or smell.  It can move up through the ground and into a home through cracks and holes in the foundation.  Radon can also get into indoor air when released from tap water from showering, washing dishes, and other household activities.  It is a known human carcinogen.  Breathing radon can lead to lung cancer.  Drinking water containing radon may cause an increased risk of stomach cancer.  Presently EPA is reviewing a standard for radon in water.
Inorganic Contaminants	Units	MCLG	AL	90th percentile sample value	# sites above AL	Date	Violation Yes/No	Typical Source of Contaminant
Lead	ppb	0	15	14	1 of 5	2006	NO	Corrosion of household plumbing system
Copper	ppm	1.3	1.3	0.15	0 of 5	2006	NO	Corrosion of household plumbing system
Source Assessment Information
		Summary of Susceptibility Factors
Source Name	Date	Low	Med	High
Bedrock Well # 2	6/10/05	8	2	2
Bedrock Well # 3	6/10/05	7	2	3
Bedrock Well # 4	6/10/05	8	3	1
Bedrock Well # 5	6/10/05	8	2	2
Bedrock Well # 6	6/10/05	7	2	3
The complete Assessment Report is available for inspection.  For more information call Gary Tetley or visit NH DES's Drinking Water Source Assessment Program web site at www.des.state.nh.us/dwspp