§ 152.35 RAINFALL LOSSES FOR THE UNIT HYDROGRAPH METHOD.

   (A)   General. Rainfall losses are to be estimated in accordance with the procedures in the ADOT Hydrology Manual. The Green & Ampt infiltration method is to be used with the Clark Unit Hydrograph Method.

   (B)   Determination of soil texture. The rainfall loss characteristics of soils for undeveloped land within the town and the contributing watersheds have been prepared as a part of the PDMP. The results are summarized in Table 3.2. A soils map and report for the Town of Payson is available from the Engineering Department. This information is to be used for all unit hydrograph models prepared for studies within the town. The engineer may use more detailed information specific to a site with written approval of the Public Works Department.

(Res. 1637, passed 2-28-02; Am. Res. 2871, passed 9-17-15; Am. Ord. 872, passed 9-17-15)

   Table 3.2: Rainfall Loss Characteristics for Undeveloped Land

Soil Class (1)	Hydrologic Soil Group (HSG) (2)	Bare Ground XKSAT In/hr (3)	Natural
			RTIMP % (4)	Veg. Cover % (5)	IA In (6)
1A	D	0.04	0	90	0.25
2A	C	0.25	0	90	0.25
3A	C	0.40	0	80	0.25
4A	C	0.40	0	75	0.25
4B	C	0.40	0	75	0.25
4C	C	0.40	0	75	0.25
5A	C	0.25	0	75	0.25
5B	D	0.06	5	75	0.25
6A	D	0.04	0	85	0.25
6B	D	0.04	0	75	0.25
6C	D	0.06	20	85	0.25
7A	C	0.40	50	25	0.25
7B	C	0.40	30	10	0.25
73	C	0.40	0	80	0.25
3730	C	0.40	5	62	0.25
3731	C	0.40	5	62	0.25
3753	C	0.40	20	62	0.25
3821	C	0.40	0	62	0.25
4140	D	0.06	0	45	0.25
4170	D	0.06	0	51	0.25
4175	C	0.40	15	76	0.25
4240	C	0.40	5	78	0.25
4241	C	0.40	10	80	0.25
4242	C	0.40	10	82	0.25
4457	C	0.40	15	75	0.25
4468	C	0.40	10	47	0.25
4469	C	0.40	10	47	0.25
5350	C	0.40	0	83	0.25
5351	C	0.40	0	83	0.25
5352	C	0.40	15	83	0.25

 

(Res. 1637, passed 2-28-02)